Solution Manual For Electrical Wiring Residential 21st Edition by Ray C. Mullin, Phil Simmons, Derek

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

Solution and Answer Guide ELECTRICAL W IRING RESIDENTIAL 21ST EDITION RAY C. MULLIN, PHIL SIMMONS, DEREK VIGSTOL CHAPTER 1: GENERAL INFORMATION FOR ELECTRICAL INSTALLATIONS TABLE OF CONTENTS Review ............................................................................................................................ 1 Safety-Related Problems .............................................................................................. 5

REVIEW Refer to the NEC or the plans in the back of this text where necessary.

1. What code sets the standard for electrical installation work in the United States? ________________________________________________________________ ____________ Answer: The NEC is the basic standard; local and state codes are to be considered also.

2. What entity enforces the requirements set by the NEC? ________________________ ________________________________________________________________ ____________ Answer: The local electrical inspection authority or Authority Having Jurisdiction(AHJ) 3. Does the NEC provide minimum or maximum standards? ________________________ Answer: Minimum 4. What do the letters ―UL‖ signify? ________________________________________________________________ ____________ Answer: When shown on an electrical product or in a certification mark, it means the product is Listed by Underwriters Laboratories. It also means that the product met applicable safety standards when it left the manufacturer’s plant.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

5. What section of the NEC states that all listed or labeled equipment shall be installed or used in accordance with any instructions included in the listing or labeling? ________________________________________________________________ ____________ Answer: NEC 110.3(B) 6. When the word ―shall‖ appears in an NEC reference, it means that it (must)(may) be done. (Select the correct word.)

Answer: Must 7. What is the purpose of the NEC? What section can this statement be found in? ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: The NEC states in 90.2(A) that ―The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.‖* 8. Does compliance with the NEC always result in an electrical installation that is adequate, safe, and efficient? Why? ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

________________________________________________________________ ____________ Answer: No. The NEC states in 90.2(B) that ―This Code contains provisions that are considered necessary for safety. Compliance therewith and proper maintenance results in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.‖* Informational Note: Hazards often occur because of overloading of wiring systems by methods or usage not in conformity with this Code. This occurs because initial wiring did not provide for increases in the use of electricity. An initial adequate installation and reasonable provisions for system changes will provide for future increases in the use of electricity.

9. Name two nationally recognized testing laboratories. ____________________________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: Underwriters Laboratories (UL) and Intertek Testing Services (ETL listing mark). There are other testing laboratories such as Canadian Standards Association (CSA), Factory Mutual (FM), and others the student might refer to that may be acceptable to the authority enforcing the Code.

10. a. Do Underwriters Laboratories and the other recognized testing laboratories ―approve‖ products? _______________________________________________________ b. What do these testing laboratories do? _______________________________________ ______________________________________________________________ _____________ ______________________________________________________________ _____________ ______________________________________________________________ _____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

Answer: a. No. Approval is up to the Authority Having Jurisdiction. See NEC 90.4 and 110.2. b. They test the products for conformance to applicable product safety standards. When the product passes these tests, the manufacturer of the product is then permitted to affix a ―label‖ (often referred to as a ―listing mark‖) that indicates the product complied with the applicable safety standard when it left their factory.

11. a. Has the NEC been officially adopted by the community in which you live? b. By the state in which you live? c. If your answer is YES to (a) or (b), are there amendments to the NEC? d. If your answer is YES to (c), list some of the more important amendments.

Answer: Student answers will vary, depending on where this course is taught.

The questions refer to local issues.

12. Does the NEC make suggestions about how to wire a house that will be occupied by handicapped persons? _______________________________________________________ Answer: Informative Annex J includes information that is intended to assist the users of the Code in properly considering the various electrical design constraints of other building systems and are part of the 2010 ADA Standards for Accessible Design. The Informative Annex is not enforceable. The basic NEC rules still apply. Local communities, counties, states, and/or other govern-mental bodies might have requirements. Check with your local inspection authority. Ask them if there are any requirements or suggestions that you might need to follow.

13. A junction box on a piece of European equipment is marked 344 cm 3. Convert this to cubic inches. (Hint: Is there a table that lists standard box sizes?) ___________________ ________________________________________________________________ ________________ Answer: 200

0.06102 = 12.204 cubic in.

14. Convert 4500 watts to Btu/hour. _________________________________________________ ________________________________________________________________ ________________ Answer: 4500

3.4129 = 15.358 Btu/hour

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

15. You will learn in Chapter 3 that residential lighting loads are based on 3 voltamperes per ft.2 (33 volt-amperes per m2). Determine the minimum lighting load required for an area of 186 m2. Do calculations for both feet squared and meters squared so you can see the difference in answers. To convert meters squared to feet squared, refer to Table 1-8. ________________________________________________________________ ________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: Step 1: Convert square meters to square feet 186

10.764 = 2002 sq. ft

Step 2: 2002

3 = 6006 volts-amperes

Working in metrics, the answer is 186

33 = 6138 volt-amperes

Note: This is an excellent example of what happens when converting inch-pound units to metrics, or vice versa. You can see that the NEC decided to ―round-off‖ 3 volt-amperes per sq. ft to 33 volt-amperes per square meter. The result is different answers. Not a big difference, but different nevertheless. Converting a rounded-off inch-pound number to metrics always results in a fractional metric value. Converting a rounded-off metric number to inch-pound units always results in a fractional inch-pound value.

There is no easy way to resolve this issue. Just follow the values as found in the NEC. No doubt inch-pound measurements will be used in this country for quite a while, so use the inch-pound values until such time that more information becomes available as on how to handle conversions in the NEC. See Tables 1-6, 1-7 and 1-8 in Electrical Wiring Residential.

There is also a comprehensive inch-pound/metric conversion table in Appendix D of Electrical Wiring Residential. Refer to it often.

SAFETY-RELATED PROBLEMS 16. What federal organization dictates requirements for work-related safety issues?

(Select the correct answer.)

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

a. NEC b. OSHA c. IAEI Answer: b. OSHA 17. What can you do to reduce or eliminate the possibility of receiving an electric shock when working on electrical circuits? (Select the correct answer.) a. Turn off the power on the circuit you are working on. b. Turn off the power on the circuit you are working on, tag it, and lock the disconnect in the OFF position, and verify the absence of voltage on the circuit. c. Turn off the power on the circuit you are working on, then tell everyone else working with you not to turn the power back on.

Answer: b. Turn off the power on the circuit you are working on, tag it, and lock the disconnect in the OFF position.

18. What is the NFPA 70E definition of a qualified person? ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: The NEC defines a qualified person as ―One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.‖* 19. Are you a qualified person? Explain your answer. ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: The answer most likely is no but the answer depends on multiple factors such as the task to be performed and whether their employer has deemed them a qualified person for the task at hand. Students taking this residential wiring course have probably not taken any courses in electrical theory, installation codes, safety, such as an OSHA course. Such courses are always part of electrical apprenticeship training programs. Some AHJs do not consider © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

the person qualified unless they have completed training and passed a certification examination. The answer could be yes. It depends on the individual and the timeline of courses the individual is required to take. The student may already have taken safety training courses, which generally are governed by national and local training programs.

20. Are low-voltage systems totally safe? Explain. ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: Not necessarily, usually depending on the voltage. A low-voltage system can give you a slight tingle that could cause a jerk reaction, resulting in personal injury. Large low-voltage systems (commercial and industrial) when shorted can result in a tremendous arc flash.

21. What NFPA standard specifically covers safety in the workplace? ____________________ Answer: NFPA 70E 22. What do the letters ―PPE‖ stand for? ________________________________________________________________ ________________ Answer: Personal Protective Equipment.

23. Explain briefly what an arc flash is. ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: An arc flash is the tremendous explosion that happens when a short circuit or ground fault occurs on an electrical system that is capable of delivering high fault current. The heat of the arc can cause severe burns. Flying particles of molten metal can cause serious injury, particularly when flying into your eyes.

The loud sound of the arc blast can cause permanent hearing damage.

Protective equipment (faceshields, arc-rated clothing, etc.) is required when working on live electrical systems.

24. Where might you obtain information about on-the-job safety and safety training?

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

________________________________________________________________ ________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: There are many sources to obtain more information regarding safety.

Apprenticeship programs, Consumer Product Safety Commission, National Safety Council, Occupational Safety & Health Act, National Fire Protection Association, and the American Heart Association are a few of the more common sources. There is also a wealth of information on various websites.

25. a Is it a safe practice to use a stepladder in which the spreaders have not been fully locked into position? _________________________________________________________ b. If the ladder collapses, who is at fault?

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

Answer: a. No b. You are responsible for your own safety. If you have the proper tools and equipment, but do not use the tools and equipment as they should be used, you might lose! * Source NFPA 70-2023.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 2: SPECIFICATIONS , ELECTRICAL S YMBOLS, AND OUTLETS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: For assistance in finding the answers to these review problems, refer to the NEC, the plans in the back of this text, and the specifications found in the Appendix.

PART 1—ELECTRICAL FEATURES 26. What is the purpose of specifications? ____________________________________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: To supplement the plans by giving specific information on materials and to help in estimating costs.

27. Refer to the specifications in the back of this text following Chapter 33. a. What electrical codes must be conformed to? ______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ b. What is the wiring method to be used in the workshop? © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

______________________________________________________________ ______________ c. What size conductors are to be used for the lighting branch circuits? _________________ AWG the small-appliance branch circuits? _________________ AWG

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

d. What section of the specifications tells us the size of the service entrance to be installed for this residence?

Answer: a. Section 5 CODES NEC, local electrical codes, and any applicable utility rules a. Section 10 WORKSHOP Electrical metallic tubing (EMT), Type NM cable protected in EMT from the joist space to the outlet, etc., or Type MC cable b. Section 12 CONDUCTOR SIZE Lighting branch circuits: 14 AWG Small-appliance branch circuits: 12 AWG c. Section 26 MAIN SERVICE 200 ampere service with one 200-ampere safety switch and one 100-ampere safety switch.

28. What is done to prevent a plan from becoming confusing because of too much detail? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Much of the information is supplied in the specifications or in notations on the plans.

29. Name three requirements contained in the specifications regarding material. a. ______________________________________________________________ ______________ b. ______________________________________________________________ ______________ c. ______________________________________________________________ ______________ Answer: a. Shall be all new b.

Size and type specified

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

c.

Carry UL label or other nationally recognized testing laboratory.

30. The specifications state that all work shall be done ______________________________ ________________________________________________________________ _______________ Answer: In a neat and workmanlike manner 31. What phrase is used when a substitution is permitted for a specific item? ___________ ________________________________________________________________ _______________ Answer: Or equivalent

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

32. What is the purpose of an electrical symbol? _____________________________________ ________________________________________________________________ _______________ Answer: To simplify the drawing and the interpretation of the various electrical devices and their arrangements 33. What is a notation? _____________________________________________________________ ________________________________________________________________ _______________ Answer: A note providing additional or more specific information 34. Where are notations found? ______________________________________________________ Answer: On the plans next to the specific symbol 35. List at least 12 electrical notations found on the plans for this residence. Refer to the plans at the back of the text. ____________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: See notes on plans. There are more than 12.

36. What three parties must be satisfied with the completed electrical installation? a. _______________________________________ b. _______________________________________ c. _______________________________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

Answer: a.

Owner

b.

Architect

c.

Inspection authority

37. What does a plan show about electrical outlets? ___________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: It shows in a simple manner, the location and type of outlet, switch, or special electrical device needed.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

38. What is an outlet? _____________________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: ―A point on the wiring system at which current is taken to supply utilization equipment‖ NEC Article 100.

39. Match the following switch types with the proper symbol. a. single-pole

________________ Sp

b. three-way

________________ S4

c. four-way

________________ S

d. single-pole with pilot light

________________ S3

Answer: a. Single-pole

Sp

b. Three-way

S4

c. Four-way

S

d. Single-pole with pilot light

S3

40. The plans show curved lines running between switches and various outlets. What do these lines indicate? ___________________________________________________________ ________________________________________________________________ _______________ Answer: The outlets that are controlled by the switches 41. Why are the lines referred to in problem 15 usually curved? ________________________ Answer: To distinguish them from building construction drawing lines 17. a. What are junction boxes used for? ____________________________________________ b. Are junction boxes normally used in wiring the first floor? Explain. _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

______________________________________________________________ ______________ ______________________________________________________________ ______________ c. Are junction boxes normally used to wire exposed portions of the basement?

Explain. ______________________________________________________________ ______ ______________________________________________________________ ______________ Answer: a. As a listed enclosure where two or more cables or raceways are joined and conductors are spliced or connected. b. No. The Code requires that they be installed so that the cover openings are accessible. This requirement would mar the appearance of the living quarters. c. Yes. The installation will not spoil the appearance of the portion of the basement that is not finished as living space.

18. How are standard sectional switch (device) boxes mounted? ____________________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: The boxes can be nailed or screwed to wood backing, mounted to brackets or metal mounting strips (Kruse supports), or mounted to adjustable bar hangers.

19. a. What is an offset bar hanger? _____________________________________________ ______________________________________________________________ ___________ ______________________________________________________________ ___________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

b. What types of boxes may be used with offset bar hangers? __________________ ______________________________________________________________ ___________ ______________________________________________________________ ___________ Answer: a. An offset bar hanger is a device on which boxes are fastened so they can be mounted between joists or studs. The hangers are available in adjusting types for different joist spacings. b. Practically any outlet or switch box which has a trade size 1 2 in. knockout can be used with offset bar hangers.

20. What methods may be used to mount luminaires to an outlet box fastened to an offset bar hanger? ___________________________________________________________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: Luminaires are mounted to an outlet box using a luminaire stud or No. 8-32 screws. Mounting hardware (straps, screws, etc.) are furnished with the luminaire. Wall- mounted luminaires that weigh not more than 6 lb. (3 kg) may be secured to a device box using not less than two No. 6-32 screws.

21. Why might you need to use a 4 in. octagon box over a 3 1⁄4 in. octagon box for a ceiling-mounted luminaire? ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: It has more space for the conductors and splices.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

22. What is the size of the opening of a switch (device) box for a single device? ________________________________________________________________ ____________ Answer: 3 in. (75 mm)

2 in. (50 mm). See Table 314.16(A).

23. The space between a door casing and a window casing is 31⁄2 in. (88.9 mm).

Two switches are to be installed at this location. What type of switches will be used? ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: The space is too small for a 2-gang plate; therefore, the switches must be combination switches trimmed with a single-gang, 2-hole faceplate. Two or 3 switches are also available on a single strap or yoke for which a single-opening, decorative-style faceplate is installed.

24. Three switches are mounted in a 3-gang switch (device) box. The wall plate for this assembly is called a _____________________________________________________ plate.

Answer: Three-gang, 3-hole switch plate 25. The mounting holes in a device (switch) box are tapped for No. 6-32 screws. The mounting holes in an outlet box are tapped for No. 8-32 screws. The mounting holes in metal boxes for attaching equipment grounding conductors are tapped for _____________ screws.

Answer: No. 10-32 26. a. Typically, how high above the finished floor in the living room are switches located? _____________________________________________________________ b. How high above the garage floor are switches located? ______________________________________________________________ ___________ Answer: a. 46 in. (1.17 m) to center. The rounded-off metric measurement is 1.15 m. b. 46 in. (1.17 m) to center. The rounded-off metric measurement is 1.15 m.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

27. a. Typically, how high above the finished floor in the living room are receptacles located? ______________________________________________________________ __ b. How high above the garage floor are receptacles located? ______________________________________________________________ ___________ Answer: a. 12 in. (305 mm) to center. The rounded-off metric measurement is 300 mm. b. 46 in. (1.17 m) to center. The rounded-off metric measurement is 1.15 m.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 2: Specifications, Electrical Symbols, and Outlets

28. Outdoor receptacle outlets in this dwelling are located _________________in. above grade.

Answer: 18 in. (450 mm). See the plans.

29. In the spaces provided, draw the correct symbol for each of the descriptions listed in (a) through (r). a. _________ Lighting panel b. _________ Clock outlet c. _________ Duplex outlet d. _________ Outside telephone e. _________ Single-pole switch f. _________ Motor g. _________ Duplex outlet, splitwired h. _________ Lampholder with pull switch i. _________ Weatherproof outlet j. _________ Special-purpose outlet k. _________ Fan outlet l. _________ Range outlet m. ________ Power panel n. _________ 3-way switch o. _________ Push button p. _________ Thermostat q. _________ Electric door opener r. _________ Multioutlet assembly

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

Answer:

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

30. The front edge of a box installed in a combustible wall must be ________________ with the finished surface.

Answer: Flush 31. List the maximum number of 12 AWG conductors permitted in the following metal boxes: a. 4 in. 1½ in. octagon box. ____________________________________________________ b. 4 11⁄16 in. 1½ in. square box. _________________________________________________ c. 3 in. 2 in. 3½ in. device box. _______________________________________________ Answer: a. 6 b. 13 c. 8 32. When a switch (device) box is nailed to a stud, and the nail runs through the box, the nails must not interfere with the wiring space. To accomplish this, keep the nail: a. halfway between the front and rear of the box. b. a maximum of 1⁄4 in. (6 mm) from the front edge of the box. c. a maximum of 1⁄4 in. (6 mm) from the rear of the box.

Answer: c. A maximum of 1 4 in. (6 mm) from the rear of the box 33. Hanging a ceiling luminaire directly from a plastic outlet box is permitted only if ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

Answer: Note to Instructor, this is an opportunity for you to emphasize the importance of being aware of requirements for electrical products in the UL Product iQ database. The marking requirements for nonmetallic boxes for support of luminaires are found in the category Nonmetallic Outlet Boxes (QCMZ). It states, A nonmetallic box, with or without a bracket or bar hanger, intended for support of a fixture weighing 50 lbs or less is marked “FOR FIXTURE/LUMINAIRE SUPPORT” on the carton. A nonmetallic box, with or without a bracket or bar hanger, intended for support of a fixture/luminaire weighing more than 50 lbs. is marked with the weight of the fixture/luminaire to be supported. Nonmetallic boxes and device plaster rings have not been investigated for support of a ceiling fixture/luminaire unless marked for use in ceilings, walls, and with the weight of the product to be supported. Nonmetallic device boxes or nonmetallic device boxes intended to be installed in an existing structure have been investigated for the support of utilization equipment weighing not more than 6 lbs.** UL testing would have been required in order for this marking to be on the box or carton.

34. It is necessary to count luminaire wires when counting the permitted number of conductors in a box according to 314.16. True or false? __________________________ Answer: False. The Exception to NEC 314.16(B)(1) states that An equipment grounding conductor or conductors or not over four fixture wires smaller than 14 AWG, or both, shall be permitted to be omitted from the calculations where they enter a box from a domed luminaire (fixture) or similar canopy and terminate within that box.* The intent of this exception is to omit counting the small wires that originate in a luminaire or ceiling suspended (paddle) fan that are spliced to the circuit conductors in an outlet box.

35. Table 314.16(A) allows a maximum ten 14 AWG wires in a 4 in square by 1½ in. deep box. However, if the box will also have two cable clamps and one fixture stud in it, what is the maximum number of 14 AWG wires allowed in this box? ________________ ________________________________________________________________ _______________ Answer: 10 –1 (for two cable clamps) –1 (for luminaire [fixture] stud) —

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

= 8 conductors permitted 36. When laying out a job, the electrician will usually make a layout of the circuit, taking into consideration the best way to run the cables and/or conduits and how to make up the electrical connections. Doing this ahead of time, the electrician determines exactly how many conductors will be fed into each box. With experience, the electrician will probably select two or three sizes and types of boxes that will provide adequate space to ―Meet Code.‖ Table 314.16(A) of the Code shows the maximum number of conductors permitted in each size metal box. In addition to counting the number of conductors that will be in the box, what is the additional volume that must be provided for the following items? Enter single or double volume allowance in the blank provided. a. one or more internal cable clamps: _______________________-volume allowance. b. for a fixture stud: _______________________-volume allowance. c. for one or more wiring devices on one yoke: _______________________volume allowance. d. for one or more equipment grounding conductors: _______________________-volume allowance.

Answer: a. Single b. Single c. Double d. Single for up to four equipment grounding conductors that enter the box. A ¼ volume allowance is required for each additional equipment grounding conductor that enters the box.

37. Is it permissible for a receptacle outlet to be located above an electric baseboard heater? ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Listed baseboard heaters include instructions that may not permit their installation below receptacle outlets. See Informational Note to NEC 210.52.

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25

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

38. What is the maximum weight of a luminaire permitted to be hung directly from an outlet box in a ceiling? ___________________ lb.

Answer: 50 pounds (22.7 kg), unless the box is listed and otherwise marked.

See NEC 410.36(A) and 314.27(A)(2).

39. Two 12-2 AWG and two 14-2 AWG nonmetallic-sheathed cables enter a box.

Each cable has an equipment grounding conductor. The 12 AWG conductors are connected to a receptacle. Two of the 14 AWG conductors are connected to a toggle switch. The other two 14 AWG conductors are spliced together because they serve as a switch loop. The box contains two cable clamps. Calculate the minimum cubic-inch volume required for the box.

Answer: See NEC 314.16. Do these box fill calculations in cubic inches, not in metrics? Until metrics become more commonly used in this country, we shall ease into the changeover from inch-pounds to metric units.

Four 12 @ 2.25 cu. in.

=

9.00 cu. in.

Four 14 @ 2.00 cu. in.

=

8.00 cu. in.

Four equipment grounding conductors, count as one (the largest wire) 1 @ 2.25 cu. in.

=

2.25 cu. in.

Two clamps, count as one (the largest 1 @ 2.25 cu. in.

=

2.25 cu. in.

One receptacle @ 2.25

2

=

One switch @ 2.00

=

4.00 cu. in.

2

4.50 cu. in.

____ TOTAL CUBIC INCHES

=

30.00 cu. in.

Two 3 2 3½ in. (75 50 65 mm) devices boxes, ganged together, provide 36 cu. in. of volume. A 4-in. square box with suitable plaster ring is also acceptable.

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26

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

40. Using the same number and size of conductors as in problem 39, but using electrical metallic tubing, calculate the minimum cubic-inch volume required for the box. There will be no separate equipment grounding conductors, nor will there be any clamps in the box.

Answer: Four 12 AWG conductors @ 2.25 cu. in.

=

9.00 cu. in.

Four 14 AWG conductors @ 2.00 cu. in.

=

8.00 cu. in.

One receptacle @ 2.25

=

4.50 cu. in.

One switch @ 2.00

2

2

=

4.00 cu. in. _____

TOTAL CUBIC INCHES

=

25.50 cu. in.

A 4 2⅛ in. (100 54 mm) square box has 30.3 cu. in. (497 cm3) of volume.

The 2-gang plaster ring would add even more volume.

41. To allow for adequate conductor length at electrical outlet and device boxes to make up connections, 300.14 requires that not less than [3 in. (75 mm), 6 in.

(150 mm), 9 in. (225 mm)] of conductor length be provided. This length is measured from where the conductor emerges from the cable or raceway to the end of the conductor. For box openings having any dimension less than 8 in.

(200 mm), the minimum length of conductor measured from the box opening in the wall to the end of the conductor is [3 in. (75 mm), 6 in. (150 mm), 9 in. (225 mm)]. (Select the correct answers.)

Answer: 6 in. (150 mm), 3 in. (75 mm) 42. When wiring a residence, what must be considered when installing wall boxes on both sides of a common partition that separates the garage and a habitable room? ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Consider the fire-resistance rating of the partition. Local codes may vary. Check this out with the local electrical inspector and/or building official in your community.

43. Does the NEC allow metal raceways to be used with nonmetallic boxes?

Yes __________________ No __________________, NEC __________________

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27

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

Answer: Yes, provided the conditions in, NEC 314.3, Exceptions No. 1 or No. 2 are complied with.

44. For ―Old Work‖ (remodels), it is common to install cables behind the finished surface by __________________ the cable from one access point to another.

Answer: fishing

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28

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

45. For ―Old Work‖ (remodels), outlet boxes are typically secured to the finished surface by: a. Super gluing the box ―ears‖ to the surface b. Brackets that swing out or snap into place c. Cutting the wall or ceiling open and securing the box to the framing member Answer: b. Brackets that swing out or snap into place PART 2—STRUCTURAL FEATURES Note: Show measurements using inches and feet.

1. To what scale is the basement plan drawn? _________________________________ Answer: ¼ in. = 1'0" 2. What is the size of the footing for the steel Lally columns in the basement? Refer to Plan 1 of 10. (Lally is the trademark used for a concrete-filled steel cylinder used as a supporting member for wood or steel girders and beams. The Lally column was named after John Lally, born in Ireland in 1859. The term lolly is also used.) _________________ ________________________________________________________________ _______________ Answer: 24"

24"

12" concrete pad footing

3. To what kind of material will the front porch lighting bracket luminaire be attached? ________________________________________________________________ _______________ Answer: The luminaire will be supported by fastening it to the electrical outlet box. The building material is vertical wood siding.

4. Give the size, spacing, and direction of the ceiling joists in the workshop. ________________________________________________________________ _______________ Answer: 2"

10" at 16" O. C. running front to rear

5. What is the size of the lot on which this residence is located? ______________________

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29

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

________________________________________________________________ _______________ Answer: 150.5'

99.0'

6. The front of the house is facing which compass direction? ________________________ Answer: SSE (south by southeast) 7. How far is the front garage wall from the curb? ________________________________ Answer: 24.916' 8. How far is the side garage wall from the property lot line? ________________________ Answer: 25' 9. How many steel Lally columns are in the basement and what size are they? ________________________________________________________________ _______________ Answer: Six, 3" 10. What is the purpose of the I-beams that rest on top of the steel Lally columns? ________________________________________________________________ _______________ Answer: To support the floor joists 11. To make sure that switch boxes and outlet boxes are set properly in the garage walls and ceilings, we need to know the thickness of the gypsum wallboard used in these locations. In the garage, what is the thickness and type of the gypsum wallboard? a. On the ―warm walls‖ of the garage? ________________________________________ b. On the ―cold walls‖ of the garage? __________________________________________ c. On the ceiling of the garage? ________________________________________________ Answer: In the garage, the ―warm walls‖ between the house proper and the garage are paneled with 5 8 in. Sheetrock Firecode gypsum panels. The outer

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30

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

walls on the inside of the garage are paneled with 12 in. Sheetrock gypsum panels.

12. Where is access to the attic provided? ___________________________________________ Answer: In the garage 13. Give the thickness of the outer basement walls. ___________________________________ Answer: 12" (The concrete blocks are 12"

8"

16".)

14. What material is indicated for the foundation walls? _______________________________ Answer: Concrete block 15. Where are the smoke detectors located in the basement? __________________________ What is the ceiling height in the basement workshop from the bottom of the joists to the floor? ________________________________________________________________ ______ ________________________________________________________________ _______________ Answer: One in the workshop near the furnace; one at the foot of the basement stairs in the recreation room; 8'0" 16. Give the size and type of the front door. ________________________________________________________________ _______________ Answer: Two 2'8"

6'8"

1 3 4 " decorative

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31

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

17. What is the stud size for the partitions between the bathrooms in the bedroom area where substantial plumbing is to be installed? _____________________________________ ________________________________________________________________ _______________ Answer: 6" 18. Who is to furnish the range hood? _______________________________________________ ________________________________________________________________ _______________ Answer: The electrical contractor as part of his bid package 19. Who is to install the range hood? _______________________________________________ ________________________________________________________________ _______________ Answer: The electrical contractor ** Source © 2019 UL LLC. * Source NFPA 70-2023.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 3: DETERMINING THE REQUIRED NUMBER OF BRANCH CIRCUITS, LIGHTING OUTLETS, AND RECEPTACLE OUTLETS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: For the following problems, you may refer to the NEC to obtain the answers.

To help you find these answers, references to Code sections are included after some of the problems. These references are not given in later reviews, where it is assumed that you are becoming familiar with the Code.

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32

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

20. What is the meaning of calculated load? _________________________________________ ________________________________________________________________ _______________ Answer: Calculated load is the result of making calculations per the NEC. Calculations are to be performed in compliance with Article 220. Both Standard and Optional methods are provided. When all loads are taken into consideration and the proper multipliers are applied, the calculated load is the final result. It is necessary for the NEC to provide guidance on how to calculate the various types of loads because the connected load and the calculated load will differ.

21. How are branch circuits rated? See NEC 210.18. ____________________________________ ________________________________________________________________ _______________ Answer: They are rated by their overcurrent protective device rating.

22. How is the rating of the branch-circuit protective device affected when the conductors used are of a larger size than called for by the Code? See NEC 210.18. ________________________________________________________________ _______________ Answer: No change 23. What dimensions are used when measuring the area of a building? See NEC 220.5(C). ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Outside dimensions

24. What spaces are not included in the floor area when calculating the load in volt-amperes per square foot? _______________________________________________________ ________________________________________________________________ _______________

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33

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

Answer: Open porches or other unfinished spaces that are not adaptable for future use 25. What is the lighting unit load per square foot for dwelling units? ________________________________________________________________ _______________ Answer: 3 volt-amperes per sq. ft (33 volt-amperes per square meter) 26. According to NEC 210.50(C), a laundry equipment outlet must be placed within _______________________ ft. (m) of the intended location of the laundry equipment.

Answer: 6 ft (1.8 m) 27. How is the total load in volt-amperes for lighting purposes determined? See NEC 220.41. ________________________________________________________________ ________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The total occupied area in square feet is multiplied by the unit load per square foot. In dwellings, the unit load per sq. ft is 3 volts-amperes per square foot (33 volt-amperes per square meter).

28. How is the total lighting load in amperes determined? _____________________________ ________________________________________________________________ _______________ Answer: The total general lighting load, as determined by 220.41, in voltamperes is divided by 120 volts.

29. How is the required number of branch circuits determined? ________________________ ________________________________________________________________ _______________ Answer: For lighting branch circuits, the load in amperes is divided by the rating of the overcurrent protective devices. For the residence in the plans, it would be 15 amperes.

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34

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

30. What is the minimum number of 15-ampere lighting branch circuits required if the dwelling has an occupied area of 4000 ft.2 (368 m2)? Show all calculations.

Answer: 4000 ft 2 × 3 volt - amperes per ft 2 120 volt s

= 100 amperes;

100 amperes 15 amperes

= 6.7 (minimum of 7 circuit s required)

We could derive the same answer as follows: 4000 f t 2 = 6.7 (m inim um of 7 circuit s required) 600

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35

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

31. How many lighting branch circuits are provided in the dwelling used in this text? ________________________________________________________________ _______________ Answer: Thirteen. See Table 3–1 in text.

32. What is the smallest size copper wire that can be used in a branch circuit rated at 20 amperes? ________________________________________________________________ _______________ Answer: 12 AWG wire unless otherwise permitted such as for motor branch circuits. Refer to Table 310.16, 240.4(D) and (G).

33. What is the maximum distance that a point along the floor line of a wall may be from a receptacle outlet in most habitable rooms of a dwelling unit? ____________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Receptacle outlets are installed so that no point along the floor line in any wall space is more than 6 ft (1.8 m) measured horizontally from an outlet in the space. Any wall space 2 ft (600 m) or greater also requires a receptacle outlet.

34. The minimum number of outdoor receptacles for a single-family residence is _____________, NEC _____________. State the required location of the receptacles. _____________ Answer: Two; NEC 210.52(E)(1); one in front and one in back, not more than 6½ ft (2.0 m) above grade 35. The Code indicates the rooms in a dwelling that are required to have switched lighting outlets or switched receptacles. Indicate ―yes‖ (switch required) or ―no‖ (switch not required) for the following areas [see NEC 210.70(A)]:

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36

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

a. attic

_________________________

b. stairway

_________________________

c. crawl space (where used for storage)

_________________________

d. hallway

_________________________

e. bathroom

_________________________

f. clothes closet

_________________________

Answer: a.

Yes, if the space is used for storage or contain equipment requiring servicing. b.

Yes, as required by NEC 210.70(A)(2)(c)

c.

Yes

d.

Yes

e.

Yes

f.

No

36. Is a receptacle required in a bedroom on a 3 ft. (900 mm) wall space behind the door? The door is normally left open. _________________________ Answer: Yes. NEC 210.52(A).

37. In a basement, at least one receptacle outlet must be installed in addition to the receptacle outlet installed for the laundry equipment. This additional receptacle outlet and any other receptacle outlets in the basement must be ______________________ protected.

Answer: GFCI protected. NEC 210.8(A)(5).

38. NEC 210.8(A)(3) requires all receptacles installed outdoors to have GFCI protection. Explain how Exception No. 1 applies and describe the conditions of the exception. ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

37

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

________________________________________________________________ _______________ Answer: GFCI protection is not required for receptacles that are not readily accessible and are supplied by a branch circuit dedicated to electric snowmelting, deicing, or pipe line and vessel heating equipment that are installed in accordance with 426.28 or 427.22 as applicable.

39. Define a branch circuit. _________________________________________________________ ________________________________________________________________ _______________ Answer: A branch circuit is defined in Article 100, Definitions, in the NEC as The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).* 40. Although the Code contains many exceptions to the basic overcurrent protection requirements for conductors, in general, the rating of the branch-circuit overcurrent device must (not be less than) (not be more than) the ampacity of a conductor. (Select the correct answer.)

Answer: Not more than. See NEC 210.18, 210.20, and 240.4.

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38

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

41. The rating of a branch circuit is based on (Select the correct answer.) a. the rating of the overcurrent device. b. the length of the circuit. c. the branch-circuit wire size.

Answer: a. The rating of the overcurrent device, NEC 210.18.

42. Small-appliance receptacle outlets are (included) (not included) in the 3-voltampere- per-square-foot calculations. (Select the correct answer.)

Answer: Not included 43. If a homeowner wishes to have a switched receptacle outlet for a swag lamp in a dining room, may this switched receptacle outlet be considered to be one of the receptacle outlets required for the 20-ampere small-appliance circuits?

Answer: No. See NEC 210.52(B)(1), Exception No. 1, and NEC 210.11(C)(1).

44. How many receptacle outlets are required on a 13 ft. (4.0 m) wall space between two doors? Refer to NEC 210.52(H). Draw the outlets on the diagram.

Answer: Since the NEC reference is to 210.52(H), we are considering a dwelling unit hallway. This section requires at least one receptacle outlet. It is permitted to be installed at any point in the hallway. See NEC 210.52(H).

45. Is a receptacle required in a hallway in a home when the hallway is 8 ft. (2.5 m) long? ________________________________________________________________ _______________ Answer: No. See NEC 210.52(H).

46. A split-level home has one stairway that has six risers between two levels of the home. Which of the following choices Meets Code? (Select the correct answer.) a. Two three-way switches must be installed (one switch at the top of the stairs, one switch at the bottom of the stairs) to control the lighting for the stairway. b. One single-pole switch is permitted on either level to control the lighting for the stairway.

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39

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

c. No switches are necessary for the stairway lighting because the lighting on the upper level and the lower level provides enough illumination on the stairway.

Answer: a. Two three-way switches must be installed (one switch at the top of the stairs, one switch at the bottom of the stairs) to control the lighting for the stairway. See NEC 210.70(A)(2)(c).

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40

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

47. A sliding glass door is installed in a family room that leads to an outdoor deck.

The sliding door has one 4 ft. (1.22 m) sliding section and one 4 ft. (1.22 m) permanently mounted glass section. For inside the family room, what does the Code say about wall receptacle outlets relative to the receptacle’s position near the sliding glass door? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The sliding portion is not considered wall space. The permanent portion is considered to be wall space and must be included in the spacing of receptacle outlets, per NEC 210.52(A)(2)(2).

48. Does the sliding door described in Question 28 count as a part of the indoor wall space? See 210.52. ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: See answer to question 28.

49. When determining the location and number of receptacles required, fixed room dividers and railings (shall be) (need not be) considered to be wall space. (Select the correct answer.)

Answer: Shall be. NEC 210.52(A)(2).

50. No point along the wall line shall be more than 6 ft. (1.8 m) from a receptacle outlet. This requirement (does apply) (does not apply) to unfinished residential basements. (Select the correct answer.)

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41

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

Answer: Does not apply. NEC 210.52(A).

51. In your own words, explain the exceptions to GFCI requirements for receptacle outlets installed in basements. Give some examples. ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: An exception is provided for a receptacle supplying only a permanently installed fire alarm or burglar alarm system. NEC 210.8(A)(5) Exception.

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42

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

52. NEC ___________________ prohibits connecting lighting and/or fire/smoke/security systems or other equipment in common (shared) areas of multifamily dwellings to one tenant’s electrical source.

Answer: NEC 210.25 53. When installing weatherproof outdoor receptacles high up under the eaves of a house intended to be used for plugging in deicing and snow-melting cable for the rain gutters, must these receptacles be GFCI protected for personnel protection?

(Yes) (No) (Select the correct answer.)

Answer: No. NEC 210.8(A)(3) and 426.28. The snow- and ice-melting groundfault protection will trip at approximately 30 milliamperes. These are not considered to be GFCI personnel protection devices, which trip in the range of 4 to 6 milliamperes.

54. A balcony on the second floor of a new residence measures 4 ft. (1.22 m) × 10 ft. (3.05 m). The balcony is accessed by a sliding door. Is a receptacle required for this balcony? Select the correct answer, and give the NEC section where the answer is found.

Yes  No  NEC ___________________ Answer: Yes. NEC 210.52(E)(3) requires that at least one receptacle be installed for a porch, balcony, or deck that is within 4 in. (102 mm) horizontally of the dwelling unit. Remember that in addition to the requirement for GFCI protection, the receptacle is required to be tamper resistant, moisture resistant and must have an ―in-use‖ cover.

55. Section 406.12(1) requires all 15- and 20-ampere, 125- and 250-volt nonlockingtype receptacles that are installed in dwelling units be listed ___________________.

Answer: Tamper-resistant 56. Receptacles that are rated 125-volts and 20-amperes that are installed in outdoor damp or wet locations are required to be listed and what type? (Select all requirements.) a. GFCI protected b. Tamper-resistant c. Weather-resistant d. Grounding-type

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43

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

Answer: c. Weather-resistant * Reprinted with permission of NFPA 70-2023.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 4: CONDUCTOR SIZES AND TYPES, W IRING METHODS, W IRE CONNECTIONS , VOLTAGE DROP, AND NEUTRAL CONDUCTOR SIZING TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the Code or the plans where necessary.

57. The largest size solid conductor generally permitted to be installed in a raceway is (10 AWG) (8 AWG) (6 AWG). (Select the correct answer.)

Answer: 10 AWG. NEC 310.3(C) requires that conductors 8 AWG and larger must be stranded unless specifically permitted or required to be solid elsewhere in the Code. 10 AWG conductors in cables are usually solid. When 10 AWG conductors are pulled into a raceway, electricians generally prefer stranded conductors.

58. What is the minimum branch-circuit wire size that may be installed in a dwelling? ________________________________________________________________ _______________ Answer: 14 AWG, Table 310.3(A) 59. What exceptions, if any, are there to the answer for problem 2? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

44

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

________________________________________________________________ _______________ Answer: Section 310.3(A) includes, except as permitted elsewhere in this Code.

Wires used in luminaires, communication wiring, security systems, bell wiring, and other low-energy systems are typically wired with conductors smaller than 14 AWG.

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45

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

60. What determines the ampacity of a wire? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The size in circular mil area, the type of insulation, whether the conductor is aluminum or copper and conditions of use including ambient temperature conditions, and the number of conductors in raceway or cable.

61. What unit of measurement is used for the diameter of wires? ______________________ Answer: The mil 62. What unit of measurement is used for the cross-sectional area of wires? ____________ ________________________________________________________________ _______________ Answer: The circular mil 63. What is the voltage rating of the conductors in Type NMC cable? ____________________ Answer: 600 volts. 334.104 64. Indicate the ampacity of the following Type THHN (copper) conductors. Refer to Table 310.16. a. 14 AWG ______________ amperes

d. 8 AWG ______________ amperes

b. 12 AWG ______________ amperes

e. 6 AWG ______________ amperes

c. 10 AWG ______________ amperes

f. 4 AWG ______________ amperes

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46

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

Answer: a. 25 amperes (90°C column of Table 310.16. Several other rules may require the use of the 60°C or 75°C column. This is true for the following ampacities as well.) b. 30 amperes c. 40 amperes d. 55 amperes e. 75 amperes f. 95 amperes

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47

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, and Neutral Conductor Sizing

65. What is the maximum operating temperature of the following conductor insulation? Give the answer in degrees Celsius. a. Type XHHW ______________

c. Type THHN ______________

b. Type THWN ______________

d. Type TW ______________

Answer: See Table 310.4(1) and Table 310.16. a.

Type XHHW (75°C wet and 90°C dry)

b.

Type THWN (75°C)

c.

Type THHN (90°C)

d.

Type TW (60°C)

66. What are the typical colors of the conductors in nonmetallic-sheathed cable for a. 2-wire cable? ______________, ______________ b. 3-wire cable? ______________, ______________, ______________ Answer: a. Black, white b. Black, white, red 67. For nonmetallic-sheathed cable, is the uninsulated conductor permitted to be used for purposes other than equipment grounding? ______________ Answer: No 68. What size equipment grounding conductor is used with the following sizes of nonmetallic-sheathed cable? a. 14 AWG ______________ b. 12 AWG ______________ c. 10 AWG ______________ d. 8 AWG ______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

Answer: See Table 250.122. a. 14 AWG b. 12 AWG c. 10 AWG d. 10 AWG 69. Under what condition is nonmetallic-sheathed cable (Type NM) permitted to be fished in the hollow voids of masonry block walls? ______________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: When such walls are not subject to excessive moisture

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49

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

70. a. What is the maximum distance permitted between straps or staples on a Type NM cable installation __________________________________________________________ b. What is the maximum distance permitted between a box and the first strap or staple in a Type NM cable installation? ________________________________________ c. Does the NEC permit Type NM, 2-wire non-metallic sheathed cable to be stapled on edge? ______________________________________________________________ _____ d. When Type NM cable is run through holes in studs and joists, must additional support be provided? ________________________________________________________ Answer: a. 4½ ft (1.4 m). NEC 334.30. b. 12 in. (300 mm). NEC 334.30. c. No. NEC 334.30. d. No, the Code considers Type NM cable run through holes in studs and joists to be adequately supported, NEC 334.30.

71. What is the difference between Type ACTHH and Type ACTH armored cables? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Type AC armored cable with Type ACTHH conductors have thermosetting insulation that become permanently hard when subjected to heat and will not soften if reheated.

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50

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

Type AC cable with ACTH conductors have thermoplastic insulation that will soften when heated.

72. Type AC armored cable may be bent to a radius of not less than ____________________ times the diameter of the cable.

Answer: Five. NEC 320.24.

73. When Type AC cable is used, what conductor protection (typically included with the cable) is required at the cable ends? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Fiber-insulating bushings commonly called anti-shorts, NEC 320.40.

74. What protection must be provided when installing a cable in a notched stud or joist, or when a cable is run through bored holes in a stud or joist where the distance is less than 1 14 in. (32 mm) from the edge of the framing member to the cable, or where the cable is run parallel to a stud or joist and the distance is less than 1 14 in. (32 mm) from the edge of the framing member to the cable? ____________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The cable must be protected by a metal plate at least 116 in. (1.6 mm) thick. Intermediate metal conduit, rigid metal conduit, rigid nonmetallic conduit,

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51

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

and electrical metallic tubing do not require this additional protection. See NEC 300.4(A)(1) and (2).

75. For installing directly in a concrete slab, (armored cable) (nonmetallic-sheathed cable) (rigid metal conduit) is permitted to be used. (Select the correct wiring method.)

Answer: Rigid Metal Conduit. A conduit wiring method is required. Nonmetallicsheathed cable is not suitable for installation in concrete, NEC 334.10 and 334.12. Armored cable is permitted only in dry locations, 320.10. A concrete slab would be considered a damp or wet location. See Definitions in Article 100 for Locations (Damp, Dry, and Wet).

76. Select the correct answer to the following statements: a. Type SE service-entrance cable is for aboveground use.

  True False

b. Type USE service-entrance cable is suitable for direct burial in the ground.

  True False c. Type SE cable with an uninsulated neutral conductor is permitted for hooking up an electric range in a new branch circuit.   True False d. Type SE cable with an insulated neutral conductor is permitted for hooking up an electric range in a new branch circuit.   True False e. Are Types SE and USE service-entrance cables permitted in your area? Yes  No  f. In which article of the NEC can this information be found? _________________________ Answer: a. True, NEC 338.12(A)(2). b. True, NEC 338.2. c. False, NEC 338.10(B)(1) and (2). d. True, NEC 338.10(B)(2). e. The answer will depend on local codes. f. Provide the source of information for your response to 20 e.

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52

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

77. When running Type NM cable through a bored hole in a stud, the nearest edge of the bored hole is required to be not less than ______________________ in. from the face of the stud unless the cable is protected by a 116 in. (1.6 mm) metal steel plate(s).

Answer: 1¼ in. (32 mm), NEC 300.4(A)(1). Watch out for building code requirements regarding notching and drilling studs and joists. Listed and marked plates less than 116 in. (1.6 mm) are permitted.

78. Where is the main service-entrance panel located in this residence? (Refer to the blueprints.) ________________________________________________________________ ____ ________________________________________________________________ _______________ Answer: Outside the garage 79. a. Is nonmetallic-sheathed cable permitted in your area for residential wiring? ______________________________________________________________ _____________ b. From what source is this information obtained? ______________________________ Answer: a. Answer can be yes or no, depending on local code regulations b. Local code regulations 80. Is it permitted to use flexible metal conduit over 6 ft. (1.8 m) in length as an equipment grounding means? (Yes) (No) (Select the correct answer.)

Answer: No. NEC 250.118(5) and 348.60.

81. Liquidtight flexible metal conduit may serve as an equipment grounding conductor in sizes up to and including ____________________ in. when used with listed fittings.

Answer: Trade size 1 14 82. The current-carrying capacity (ampacity) of aluminum wire, or the maximum over-current protection in the case of 14 AWG, 12 AWG, and 10 AWG conductors, is less than that of copper wire for a given size, insulation, and temperature of 30°C. Refer to Table 310.16 and 240.4(D) and complete the

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

following table. Important: Where the ampacity of the conductor does not match the rating of a standard fuse or circuit breaker as listed in Table 240.6(A), 240.4(B) permits the selection of the next ―higher‖ standard rating of fuse or circuit breaker if the next higher standard rating does not exceed 800 amperes.

Nonstandard ampere ratings are also permitted.

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54

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

WIRE (AWGKCMIL)

COPPER

ALUMINUM

Overcurrent Protection

Ampacity

Overcurre nt Protectio n

Ampacity

Insulation Type 12 AWGTHHN 10 AWGTHHN 3 AWGTHW 4/0 THWN 500 kcmil THWN

Answer: In accordance with NEC 110.14(C)(1), assume 60°C terminals for conductor sizes 14 AWG through 1 AWG and 75°C terminals for conductors larger than 1 AWG. Ampacities are from NEC Table 310.15(B)(16). The ―roundup‖ rules from NEC 240.4(B) are used.

COPPER Ampacity WIRE

ALUMINUM

Overcurrent

Ampacity

Protection

Overcurrent Protection

12 AWG THHN

30

20

25

15

10 AWG THHN

40

30

35

25

3 AWG THW

100

100

75

80

4/0 THWN

230

250

180

200

500

380

400

310

350

kcmil THWN

83. It is permissible for an electrician to connect aluminum, copper, or copper-clad aluminum conductors together in the same connector without special precautions. (True) (False) (Select the correct answer.)

Answer: False, unless the connector is identified for such combinations. The carton would be so marked.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

84. Terminals of switches and receptacles marked CO/ALR are suitable for use with __________________, __________________, and __________________, conductors.

Answer: Direct connection of copper, aluminum, and copper-clad aluminum conductors 85. Wire connectors marked AL/CU are suitable for use with __________________, __________________, and __________________ conductors.

Answer: Copper, aluminum, and copper-clad aluminum 86. A wire connector bearing no marking or reference to AL, CU, or CO/ALR is suitable for use with (copper) (aluminum) conductors only. (Select the correct answer.)

Answer: Copper 87. When exposed Type NM cable is run through a floor, it must be protected by at least ______________ in. (______________ mm) of ______________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: 6 in. (150 mm) of rigid metal conduit, intermediate conduit, electrical metallic tubing, Schedule 80 PVC, Type RTRC marked with the suffix-XW, or other approved means. It is up to the electrical inspector to approve other means.

See NEC 334.15(B).

88. When nonmetallic-sheathed cables are bunched or bundled together for distances longer than 24 in. (600 mm), what happens to their current-carrying ability (ampacity) when the current-carrying conductors in all the cables combined exceeds a total of three? ________________________________________________________________ _______________ Answer: Their ampacities must be reduced accordingly. See NEC 310.15(C)(1) and 334.80.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

89. In diagrams A and B, nonmetallic-sheathed cable is run through the cold air return. Which diagram ―Meets Code‖? A _____________ B _____________

Cold air return

Cold air return

Cable

Cable

Select one.

Answer: A. See NEC 300.22(C).

90. The marking on the outer jacket of a nonmetallic-sheathed cable indicates the letters NM-B. What does the letter ―B‖ signify? _________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: That the conductors are rated at 90°C. However, the ampacity of the wire shall be based on the 60°C column of NEC Table 310.16. See NEC 334.112 and 334.80.

91. A 120-volt branch circuit supplies a resistive heating load of 10 amperes. The distance from the panel to the heater is approximately 140 ft. Calculate the © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

voltage drop using (a) 14 AWG, (b) 12 AWG, (c) 10 AWG, (d) 8 AWG copper conductors. See 210.19, Informational Note ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: a. Ed 

K  I  L  2 12.9  10  140  2   8.79 volts drop CMA 4110

b. Ed 

12.9  10  140  2  5.53 volts drop 6530

c. Ed 

12.9  10  140  2  3.48 volts drop 10,380

d. Ed 

12.9  10  140  2  2.19 volts drop 16,510

It might help for the instructor to explain K values.

Table 8 in the NEC provides conductor resistance values in ―Ohms per 1000 ft‖ @ 75°C (167°F). The 75°C temperature approximates the conductor at a fully loaded condition. We all know the resistance of the conductor will change as its temperature changes. This is the direct-current resistance value. For alternatingcurrent circuits, impedance is determined using resistance and reactance values.

For our example, we keep it easy and simply use resistance values.

Take a look at a 10 AWG copper conductor. It has 10,380 circular mils of cross-sectional area and has a resistance of 1.24 ohms per thousand ft, (0.00124 ohms per ft.). This value if for uncoated copper conductors, like a conductor with THHN insulation.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

For tin coated copper conductors like the old Type R rubber insulated conductors, the resistance values are 1.29 ohms per thousand ft. (0.00129 ohms per ft.). Copper had a bad deteriorating effect on rubber, therefore, by coating the copper conductor with tin, the problem was resolved.

Now think of this 10 AWG conductor as being made up of 10,380 individual conductors, all wrapped together and connected in parallel. Next, think about how to calculate resistances in parallel by using Ohm’s law.

RT = R of one resistor  number of resistors R of one resistor = RT

number of resistors.

Therefore, 0.00124 10,380 = 12.87 ohms (approximate) per mil foot. For simplicity, in the above calculations, we used a K factor of 12.9.

To repeat, for every foot of 10 AWG conductor, think of it as 10,380 conductors, each having a resistance of 0.00124 ohm, connected in parallel.

This then is the approximate resistance value of ONE MIL FOOT OF COPPER WIRE. Bear in mind that temperature of the conductor and power factor of the circuit will affect the impedance. But we are looking for a simpler method to calculate voltage drop, and a reasonably accurate answer. This formula works fine for small conductors but gets less accurate as conductor size increases. This difference is due to the ―skin effect,‖ where most of the current flows on the outer side of the conductor.

In the VOLTAGE DROP FORMULA, we use ohms per mil foot. By doing this, we insert the CIRCULAR MIL AREA (CMA) of the particular size conductor that we are using into the formula.

That is why you see the value of 12.9 ohms per mil ft for the copper conductor in each example—because the CMA of the conductor you are using takes care of adjusting the answer no matter what size conductor you are using.nother method of determining the K factor of conductors is to multiply the dc resistance of the conductor from NEC Table 8 of Chapter 9 by the circular mill area and divide this by 1000. You will find a slight variation in the result.

For more accurate calculations, refer to Bussmann’s Bulletin SPD, where power factor is taken into consideration.

92. In problem 35, it is desired to keep the voltage drop to 3% maximum. What minimum size wire would be installed to accomplish this 3% maximum voltage drop? See 210.19, Informational Note

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59

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

Answer: 3% of 120 volts is 3.6 volts. Therefore, the 10 AWG conductor or larger would be correct. Note to instructor: If time permits, you could ask the student to do a few calculations of the wattage output of the 10-ampere heater at the different voltages resulting from using different wire sizes.

93. NEC 215.2, 220.61, 230.42, and 310.12(D) state that the neutral conductor of a residential service or feeder can be smaller than the phase conductors, but only ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: But only if it can be verified that the reduction in the size of the neutral will result in a conductor capable of safely carrying the load, per NEC 215.2, 220.61, and 230.42.

94. The 90°C ampacity of a 4 AWG THHN from Table 310.16 is 95 amperes. What is this conductor’s ampacity if connected to a terminal listed for use with 60°C wire? ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: 70 amperes. See NEC 110.14(C)(1) and Table 310.16.

95. If, because of some obstruction in a wall space, it is impossible to keep a Type NM cable at least 1 14 in. (32 mm) from the edge of the stud, then it shall be protected by a metal plate at least ________________________ in. thick.

Answer: 116 in. (1.6 mm). See NEC 300.4(A)(1) and (2).

96. The recessed fluorescent luminaires installed in the ceiling of the recreation room of this residence are connected with trade size 3 8 flexible metal conduit.

These flexible connections are commonly referred to as fixture whips. Does the flexible metal conduit provide adequate grounding for the luminaires, or must a separate equipment grounding conductor be installed? ______________________________________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The flexible metal fixture whip is adequate for grounding the recessed luminaires because the whips will not be longer than 6 ft and will be protected by 15-ampere overcurrent devices. See NEC 348.20(A)(2)(c) and 250.118(5).

97. Liquidtight flexible metal conduit will be used to connect 5 ft. from the exterior disconnection means to the air-conditioner unit. It will be trade size 3 4 and the overcurrent protection device is 50 amps. Must a separate equipment grounding conductor be installed in this LFMC to ground the air conditioner properly? __________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: No. Using proper fittings, liquid tight flexible metal conduit is acceptable as a grounding means up to and including trade size 1 1 4 provided proper fittings are used, the flex is not over 6 ft long, and the overcurrent device is not over 60 amperes. See NEC 250.118(6).

98. Based on the same information provided in question 41, what would be the maximum size overcurrent device permitted to protect the air-conditioning unit and still comply with the NEC where the LFMC is used as an equipment grounding conductor? ________________________________________________________________ _______________ Answer: 60-ampere overcurrent device. 250.118(6)c.

99. Is the 20-ampere small-appliance branch circuits in the kitchen of a residence permitted to also supply the lighting above the kitchen sink and under-cabinet lighting? Select the correct answer. Yes No

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

Answer: No. See NEC 210.11(C)(1) and 210.52(B)(2).

100.

A 30-ampere individual branch circuit is installed for an electric clothes dryer. What is the maximum ampere rating of a dryer permitted by the NEC to be cord-and-plug connected to this circuit? Select the correct answer. a. _________________ 30 amperes b. _________________ 24 amperes c. _________________ 15 amperes Answer: b. 24 amperes. This is 80% of the branch-circuit ampere rating as required by NEC 210.23(B).

101.

In many areas, metal framing members are being used in residential construction. When using nonmetallic-sheathed cable, what must be used where the cable is run through the metal framing members? _________________ Answer: A listed insulating bushing or grommet to protect the cable from being damaged by the sharp edges of the holes in the metal framing members. See NEC 300.4(B)(1).

102.

Are set screw–type connectors permitted to be used with armored cable that has an aluminum armor? ___________________________________________________________ Answer: No. This is a UL requirement. Always use listed connectors identified as suitable for the application.

103.

The most common Type AC cable used today has 90°C thermoplastic conductors. What is the correct designation for this type of armored cable? _________________________ Answer: Type ACTHH

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

104.

If you saw two different types of SE cables, how would you distinguish them? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Type SER service-entrance cable has an insulated neutral conductor and a bare equipment grounding conductor, and it is round. Type SEU serviceentrance cable has an uninsulated wrap-around neutral conductor and a U shape.

105.

Select the correct answer defining the type of location:

a. A raceway installed underground 

 (Dry) (Wet)

b. A raceway installed in a concrete slab that is in direct contact with the earth c. A raceway installed in a concrete slab between the first and second floor d. A raceway installed on the outside of a building exposed to the weather e. The interior of a raceway installed on the outside of a building exposed to the weather 

  (Dry) (Wet)   (Dry) (Wet)   (Dry) (Wet)  (Dry) (Wet)

Answer: a, b, d, and e locations are wet locations. c is a dry location. See NEC 300.5, 300.9, and 310.10(A), (B), and (C). Conductors installed in these conditions must be listed for wet locations.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

106.

As permitted, installing cables of entirely nonmetallic sheaths into the top of a surface-mounted enclosure through one or more nonflexible raceways, the raceways shall be not less than __________________ and not more than __________________ in length, provided they meet all of the following conditions: a. Nonmetallic-sheathed cable secured within __________________ in. from where it emerges from the raceway. b. The raceway comes out of the top of the enclosure and making sure it does not penetrate a __________________ __________________. c. A fitting is needed at each end of the raceway, and it must remain accessible after the install in order to protect against __________________. d. Raceways must be __________________ or __________________ to prevent access into the enclosure through the raceway. e. The cable sheath must be __________________ and extend into the enclosure at least a __________________ in. f. The raceway must be __________________. g. When cable(s) are installed in raceways as mentioned above, what NEC Table and Chapter provide guidance on the cable fill requirements for complete conduit and tubing systems, which this is to be considered. Table __________________, Chapter __________________.

Answer: not less than 18 in. (450 mm) and not more than _10 ft (3.0 m)_________ in length,: a. ____12____ in. b. structural ceiling. c. abrasion. d. Sealed___ or plugged. e. ___ continuous ¼ in. f. fastened at its outer end and at other points in accordance with the applicable article. g. Table_1_________, Chapter _______9_______.

Solution and Answer Guide

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 5: CONDUCTOR IDENTIFICATION , SWITCH CONTROL OF LIGHTING CIRCUITS, BONDING/GROUNDING OF W IRING DEVICES, AND INDUCTION HEATING TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note to instructor: The wiring diagrams that the student is asked to complete in Electrical Wiring Residential are shown in the Instructor’s Guide. To keep the diagrams uncomplicated and uncluttered, the equipment grounding conductor (EGC) connections are not shown. Drawing wiring diagrams is difficult. Colored pencils or fine tip marking pens are useful, and neatness helps. The many ways to connect EGCs is covered in detail in the text. There are many variables, such as: is the wiring method NMC, AC, MC, or is the wiring method a metallic or nonmetallic raceway? Are the boxes metallic or nonmetallic? Discuss this with your students. If you want the EGC connections shown, then tell this to the student. If you are fortunate to have a hands-on lab, then of course you will require that all connections be properly made.

IMPORTANT Several significant revisions were made to the requirement added to the 2011 NEC that a grounded circuit conductor (usually a neutral) be provided at each location where a switch controls a lighting load. See 404.2(C) in the 2023 NEC for the latest requirements. The illustrations in Electrical Wiring Residential have been revised to show these revisions. Since there are many ways the switches can be installed and branch circuit run, perhaps the best approach is to thoroughly cover the general requirement and exceptions with your students.

There is more than one way to make up the connections in the wiring diagrams for Questions 8, 9, 12, and 14. Encourage your students to discuss other ways to make up the connections.

NEC 200.7(C)(1) has requirements on the use of a reidentified conductor with white insulation as an ungrounded conductor for use in single-pole, 3-way and 4-way switch loops. You will want to carefully review these requirements with your students.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

Color coding for the travelers in 3-way and 4-way switching arrangements is usually up to local custom. You might want to get your students to offer their ideas of how they color code travelers.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

SOLUTIONS Note: Refer to the Code or the plans where necessary.

107.

The identified grounded circuit conductor must be _________________ or _________________ in color.

Answer: White or gray 108.

Explain how lighting switches are rated. __________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Lighting switches are rated for voltage and amperage. Switches are either AC/DC general-use snap switches, or AC general-use snap switches. The AC/DC general-use snap switch may be T-rated as well.

109.

A T-rated switch may be used to its ____________________________ current capacity when controlling an incandescent lighting load.

Answer: Rated 110.

What switch type and rating is required to control five 300-watt tungsten filament lamps on a 120-volt circuit? Show calculations. ___________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: I 

W 1500   12.5 amperes connected load E 120

The load is a tungsten load. AC/DC general-use snap switches, and AC/DC general-use snap switches marked with a ―T‖ may be used up to their ampere rating.

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111.

List four types of lighting switches.

a. _______________

c. _______________

b. _______________

d. _______________

Answer: a. Single-pole switch b. Double-pole switch c. Three-way switch d. Four-way switch 112.

To control a lighting load from one control point, what type of switch would be used? ________________________________________________________________ _______________ Answer: Single-pole switch 113.

Single-pole switches are always connected to the _______________________ wire.

Answer: Ungrounded ―hot‖ wire Note to instructor: Be sure that the white grounded circuit conductor in nonmetallic-sheathed cable, armored cable, or Type MC, whenever used as an ungrounded conductor, is clearly reidentified. In the text, conductor colors are clearly shown in color.

114.

Complete the connections in the following arrangement so that both ceiling light outlets are controlled from the single-pole switch. Assume the installation is in a cable-type wiring method.

Answer: There is more than one way to make the connections. This diagram is but one way. Encourage students to discuss other ways to make the connections.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

115.

Complete the connections for the diagram. Installation is in a cable-type wiring method.

Answer:

116.

A 3-way switch has how many terminals? ________________________________________ Answer: Three terminals, one common and two travelers.

117.

What type(s) of snap switches must be installed to control a luminaire from multiple locations? (List all that apply.) __________________________________________________ ________________________________________________________________ _______________ Answer: Three-way switches, two are required 118.

Using an EMT wiring method, complete the connections in the following arrangement so that the lamp may be controlled from either 3-way switch.

Answer: There is more than one way to make the connections. This diagram is but one way. Encourage students to discuss other ways to make the connections.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

119.

When connecting 4-way switches, care must be taken to connect the travelers to the _____________________________ terminals.

Answer: Proper pairs of terminals 120.

Show the connections for a ceiling outlet that is to be controlled from any one of three switch locations. The 120-volt feed is at the light. Use colored pens or pencils. Assume the installation is in EMT.

Answer:

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

121.

Match the following switch types with the correct number of terminals for each.

Three-way switch

Two terminals

Single-pole switch Four terminals Four-way switch

Three terminals

Answer:

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

Three-way switch

Two terminals

Single-pole switch

Four terminals

Four-way switch

Three terminals

122.

When connecting single pole, 3-way, and 4-way switches, they must be wired so that all switching is done in the _____________________________ circuit conductor.

Answer: Ungrounded (unidentified, ―hot‖). See NEC 404.2(B).

123.

What section of the Code emphasizes the fact that all circuiting must be done so as to avoid the damaging effects of induction heating? _________________________________ Answer: NEC 300.3(B), 300.20, and 300.35 124.

If you had to install an underground 3-wire feeder to a remote building using three individual conductors, which of the following installations ―Meets Code‖? Select the correct installation.

Answer: B 125.

Is it always necessary to attach the bare equipment grounding conductor of a nonmetallic-sheathed cable to the green hexagon–shaped grounding screw on a receptacle? Explain. ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: No. If the receptacle has an approved self-grounding strap and the receptacle is connected to a properly grounded metal box or if the metal yoke of the receptacle has metal-to-metal contact between the receptacle and the grounded metal box. See NEC 250.146.

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126.

List the methods by which an equipment grounding conductor is connected to a device box. ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: By connecting (terminating) the equipment grounding conductor under the ―GRND‖ screw in the box or by fastening the grounding conductor to the box with a ground clip 127.

When two nonmetallic-sheathed cables (Type NM-B) enter a box, is it permitted to bring both of the bare equipment grounding conductors directly to the grounding terminal of a receptacle, using the terminal as a splice point? _____________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

________________________________________________________________ _______________ Answer: No. NEC 250.148 states in part that The arrangement of grounding connections shall be such that the disconnection or the removal of a receptacle, luminaire, or other device fed from the box will not interfere with or interrupt the grounding continuity. * 128.

The installation in the accompanying drawing is wired with EMT. Receptacle outlet B is only a few feet from switch C. Receptacle outlet A is only a few feet from switch D. The electrician saved a considerable amount of wire by picking up the supply (feed) for switch C from receptacle B and the switch leg (return) from switch D. What is wrong with this installation?

________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: This diagram is an example of how induction heating can occur in metal raceways by trying to save a few dollars on the cost of wire and is a clear violation of 300.20(A) of the Code. It also is a clear violation of 300.3(B).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 5: Conductor Identification, Switch Control of Lighting Circuits, Bonding/Grounding of Wiring Devices, and Induction Heating

129.

Define an equipment grounding conductor. _______________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: A conductive path(s) that is part of an effective ground-fault current path and connects normally non–current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both. *

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130.

When metal switchplates are used with nonmetallic boxes, the faceplate must be grounded according to 404.9(B). How is this accomplished? ________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The easiest way to ground the faceplate is to install toggle switches that have a provision for the connection of an equipment grounding conductor. The metal faceplate, after it is installed, is considered grounded through the No. 6-32 faceplate mounting screws. See NEC 404.9(B).

131.

Does the Code permit the ampacity of switch legs to be less than the ampere rating of the branch circuit? __________________________________________________________ Answer: No. Switch legs, whether single-pole or for 3-way or 4-way switching, must have the same ampere rating as the branch-circuit rating, NEC 210.18, 210.20, and 210.24, and Table 210.24. Also see NEC 240.4(E). It is important to remember that switch legs are not ―taps.‖ There are certain instances where the ―home run‖ of a branch circuit is larger than the branch-circuit rating. For example, a 12 AWG conductor might be used for 15-ampere branch-circuit wiring because of voltage drop considerations. Switch legs for this wiring could be a 14 AWG, although it certainly would be confusing at a later date to find 14 AWG and 12 AWG conductors in the same circuit, even though the branch-circuit overcurrent protection is 15 amperes. It would also be possible for someone to easily change the 15-ampere overcurrent device to a 20-ampere device, not realizing that 15-ampere switch legs had been installed throughout that particular branch circuit.

It is best to use the same size conductors throughout the branch circuit to avoid confusion.

132.

Does the Code permit connecting receptacles to a 20-ampere branch circuit using short lengths of 14 AWG conductors as the pigtail between the receptacle terminals and the 12 AWG branch-circuit conductors? _____________________________________ Answer: No. The smaller taps permitted in Table 210.24 are for other than the receptacle circuits.

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133.

Do receptacles that have back-wired push-in terminals accept 12 AWG conductors? Give a brief explanation for your answer. _________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: No. This is a UL requirement. NEC 110.3(B) states Installation and Use. Equipment that is listed, labeled, or both shall be installed and used in accordance with any instructions included in the listing or labeling.* The UL product standard requirements for this type of termination do not allow 12 AWG conductors to be inserted into the back-wiring holes. The holes are only large enough for a 14 AWG conductor.

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134.

Under which of the following situations is it most likely that a grounded conductor will be required at a switch location when the wiring method is a cable? (Select all that apply.) a. A single pole wall switch is located at the entrance to the living room of a single-story dwelling and the attic is accessible through an attic access that is located in the garage. b. A single pole wall switch is located at the entrance to the living room that is located on the first story of a two-story dwelling and the attic is accessible through an attic access that is located in an upper bedroom closet. c. A 3-way wall switch is located at each end of a hallway on the first floor of a dwelling and the attic is accessible through an attic access that is located in the garage. d. A wall switch that is located at a side entrance to an attached garage. The switch is located by the personnel door and is for the outdoor light.

Answer: b. 404.2(C).

135.

Time switches are designed to provide automatic control of electrical loads.

True  False  Answer: True 136.

A grounded conductor (neutral) is required at switch locations if the wiring method is (select one answer) a. Type NM cable. b. Electrical metallic tubing (EMT). c. Type MC cable. d. Any of these.

Answer: d.

137.

Which of the following rooms or spaces is NOT required to have a grounded conductor at the switch location? (Select one answer.) a. Kitchen

d. Stairway

b. Bathroom c. Garage

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: c.

138.

Timers are installed so they operate (select the correct answer)

a. in series with the load to be controlled. b. in parallel with the load to be controlled.

Answer: a.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

139.

Astronomical time clocks control the on and off times for loads based on

a. their specific location on the planet. b. the light level at their location similar to that of a photocell.

Answer: a * Source NFPA 70-2023.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 6: GROUND -F AULT CIRCUIT INTERRUPTERS , ARC-FAULT CIRCUIT INTERRUPTERS , SURGE PROTECTIVE DEVICES, IMMERSION DETECTION CIRCUIT INTERRUPTERS , AND APPLIANCE LEAKAGE CURRENT INTERRUPTERS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW 140.

Explain the operation of a ground-fault circuit interrupter. Why are GFCI devices used? Where are GFCI receptacles required? ______________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: A ground-fault circuit interrupter (GFCI) senses an unbalanced current flow. An unbalanced current occurs when a ground fault exists. In other words, some of the current flow in a circuit is going to a grounded object from the ―hot‖ conductor. This current flow may result in injury or death if it passes through a

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

human being. The GFCI interrupts the flow of current if an unbalanced current exists. A current in excess of 6 milliamperes causes the GFCI to trip the circuit off. GFCI protection may be provided by a branch-circuit breaker, by a dual-function AFCI/GFCI circuit breaker or by a GFCI receptacle.

GFCI protection is required at several locations in a dwelling including bathrooms, kitchens, garages, outdoors, and within 6 ft (1.8 m) of the top inside edge of the bowl of sinks as well as adjacent to swimming pools and hot tubs.

See NEC 210.8 and Article 680.

141.

Residential GFCI devices are set to trip on a ground-fault current above _______________________ milliamperes.

Answer: 6 milliamperes

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142.

GFCI is required for which receptacles installed in residential garages? ______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: See NEC 210.8(A)(2). All 125-voltthrough 250-volt receptacles supplied by single-phase circuit rated 150-volts to ground or less in garages must have GFCI protection.

Similar requirements for receptacles in basements are found in NEC 210.8(A)(5).

143.

Which receptacles in a kitchen are required to be GFCI protected? __________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: GFCI protection is required for all receptacles are in the kitchen.

144.

Is it a Code requirement to provide GFCI protection of receptacles in a fully carpeted, finished recreation room in the basement? _______________________________________ Answer: Yes, as the NEC no longer refers to ―unfinished‖ basements. NEC 210.8(A)(5).

145.

A homeowner calls in an electrical contractor to install a separate 20ampere branch circuit in the basement (unfinished) for a freezer. Is GFCI protection of the receptacle required? ________________________________________________________________ _______________ Answer: Yes. See NEC 210.8(A)(5).

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146.

GFCI protection is available as (a) branch-circuit breaker GFCI, (b) feeder circuit-breaker GFCI, (c) individual GFCI receptacles, and (d) feed-through GFCI receptacles. In your opinion, for residential use, what type would you install? ______________________ Answer: The student could indicate any of the four choices. The branch circuit layout including the requirement for AFCI protection will be a deciding factor.

147.

Explain why GFCI protective devices won’t work on multiwire branch circuits unless they are designed for that purpose. ______________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The GFCI device will trip unnecessarily due to an imbalance of current in the common neutral conductor. ._________________________________________ ________________________________________________________________ _____

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148.

Extremely long circuit runs connected to a GFCI circuit breaker might result in which of the following? (Select the correct answer.) a. nuisance tripping of the GFCI. b. loss of protection. c. the need to reduce the load on the circuit.

Answer: a. Nuisance tripping of the GFCI 149.

If a person comes in contact with the ―hot‖ and grounded conductors of a 2-wire branch circuit that is protected by a GFCI at the same time, will the GFCI trip OFF? Why or why not? _______________________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: No, because the current to and from the person would most likely be equal.

A GFCI trips only on an imbalance of current between the ungrounded (hot) and grounded (neutral) conductors.

150.

What might happen if the line and load connections of a feed-through GFCI receptacle were reversed? ________________________________________________________________ _ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Answer: Because the actual tripping mechanism is on the load side of the line supply terminals, if the 120-volt circuit were to be connected to the load terminals and a ground fault should occur, the GFCI would trip off. All downstream devices would be deenergized, but the GFCI itself would still be energized. Newer generation GFCI receptacles will not function if improperly connected.

151.

Is a GFCI receptacle permitted to be installed as a replacement in an old installation where the 2-wire circuit has no equipment grounding conductor? ___________________ Answer: Yes, according to NEC 406.4(D) and if the equipment to be supplied is not required to be grounded by Article 250 or manufacturer’s instructions.

152.

What two types of receptacles are permitted to be used to replace a defective receptacle in an older home that is wired with knob-and-tube wiring where no equipment grounding means exists in the box? ____________________________________ ________________________________________________________________ _______________

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Answer: Either a nongrounding-type receptacle or a GFCI receptacle. The GFCI receptacle must be marked ―No Equipment Ground.‖ See NEC 406.4(D). An equipment ground must be installed according to NEC 250.130(C) if the equipment to be supplied is required to be grounded by Article 250 or by the manufacturer’s instructions.

153.

You are asked to replace a receptacle located in an upper kitchen cabinet for connection of a microwave. On checking the wiring, you find that the circuit is not part of the small appliance branch circuits supplying the countertops, the wiring method is EMT, and the wall box is properly grounded. The receptacle is of the older style 2-wire type that does not have a grounding terminal. You remove the old receptacle and replace it with which of the following? (Select the correct answer.) _________________ a. the same type of receptacle as the type being removed. b. a receptacle that is of the grounding type. c. a GFCI receptacle.

Answer: c is correct. If the receptacle to be replaced is in an area that requires GFCI protection according to the latest edition of the NEC, then the replacement receptacle must be GFCI protected, NEC 406.4(D)(3).

154.

What color are the terminals of a standard grounding-type receptacle? _____________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The ungrounded ―hot‖ terminal is brass colored; the grounded conductor terminal is white or silver; the grounding terminal is green.

155.

What special shape and color are the grounding terminals of receptacles and other devices? ________________________________________________________________ ______ ________________________________________________________________ _______________ Answer: The grounding equipment terminal is hexagonal and greenish.

156.

Construction sites can be dangerous because of the manner in which extension cords, portable electrical tools, and other electrical equipment are used © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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and abused. To reduce this hazard, 590.6(A)(1) of the NEC requires that all 125volt, single-phase, 15-, 20-, and 30-ampere receptacle outlets used for temporary wiring during construction be _______________ protected.

Answer: NEC 590.6 and 590.6(A) require that all 125-volt, single-phase, 15-, 20, and 30- ampere receptacle outlets used for temporary wiring during construction must be GFCI protected. In some cases, workers use receptacles that are part of the permanent wiring of the structure. These must be GFCI protected. An alternative is to use portable cord sets that have integral GFCI protection.

For other than 125-volt, single-phase, 15-, 20-, and 30-ampere receptacle outlets used for temporary wiring during construction, the outlets must be (a) GFCI protected or (b) have a written assured equipment grounding conductor program continuously enforced at the site. This is covered in NEC 590.6(A)(1) and (2).

157.

Circuit A1 supplies GFCI receptacles ➀ and ➁. Circuit A2 supplies GFCI receptacles ➂ and ➃. Receptacles ➀ and ➁ are feed-through type. Using colored pencils or marking pens, complete all connections.

Answer: Note: In the diagram, the equipment grounding terminals on the receptacles are shown as being connected to ground. This is assumed to be accomplished by the No. 6-32 screws that secure the receptacles to the metal device boxes. If the wall boxes are nonmetallic, then the equipment grounding terminals on the receptacles must be connected to the equipment grounding conductor(s) in the box. The text covers this in detail. © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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When students studied Chapter 6, they learned that GFCI circuit breakers are not permitted to share a neutral on a multiwire branch circuit. In this diagram (1) the circuit breakers are not of the GFCI type, and (2) the receptacles are of the GFCI type. In this diagram, the GFCI receptacles are not sharing the neutral. This diagram is correct.

158.

The term SPD is becoming quite common. What do the letters stand for? ___________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Surge protective device, previously known as transient voltage surge suppressor (TVSS) 159.

Transients (surges) on a line can cause spikes or surges of energy that can damage delicate electronic components. An SPD device contains one or more components that bypass and absorb the energy of the transient. What section in the NEC requires these devices be installed on dwelling unit services?

Answer: Section 230.67 160.

Undesirable ―noise‖ on a circuit can cause computers to lock up, lose their memory, and/or cause erratic performance of the computer. This noise does not

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damage the equipment. The two types of this noise are EMI and RFI. What do these letters mean? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: EMI means electromagnetic interference. RFI means radio frequency interference, often referred to as ―dirty power.‖

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161.

Are SPD receptacles permitted to be installed in standard device boxes? _____________ Answer: Yes 162.

Some line transients are not damaging to electronic equipment but can cause the equipment to operate improperly. The effects of these transients can be minimized by installing what type of SPD at the point of utilization? ______________________________ Answer: A Type III surge protective device 163.

Briefly explain the operation of an immersion detection circuit interrupter (IDCI). ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: An immersion detection circuit interrupter operates on the principle that if it is dropped into water, the leakage current that will flow between a ―live‖ part within the appliance and the ―sensor‖ within the appliance will signal the IDCI to trip to the OFF position, thereby opening both conductors supplying the appliance. The IDCI is an integral part of the attachment plug cap.

164.

What range of leakage current must trip an IDCI? _________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: An IDCI must trip when it senses a leakage current of 4 to 6 milliamperes.

165.

What range of current flowing through a human being can potentially cause muscle contractions that will keep him from letting go of the live wire? ________________ milliamperes Answer: 23 mA 166.

Other than for a few exceptions, the NEC requires that all systems having a voltage of over ________________ and below 1000 volts be grounded.

Answer: 50 volts 167.

In an old house, an existing nongrounding, non–GFCI-type receptacle in a bathroom needs to be replaced. According to 406.4(D)(3), this replacement receptacle shall be which of the following? (Select the correct answer.) a. a nongrounding-type receptacle. b. a GFCI-type receptacle or GFCI protected in some other way, such as changing the breaker that supplies the receptacle to a GFCI type.

Answer: b. It makes no difference whether a grounding means does or does not exist in the box. NEC 406.4(D)(3) requires that a replacement receptacle must be GFCI protected if the receptacle is in any location where the present NEC requires GFCI protection of the receptacle. NEC 210.8(A)(1) requires that receptacles in bathrooms be GFCI protected.

168.

Does all equipment installed in the kitchen of the residence referenced in this text have to be GFCI protected? Explain. ______________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Not all equipment that is installed in a kitchen must be GFCI protected, but all receptacles must be. See 210.8(D) for a list of specific appliances requiring GFCI protection.

169.

NEC 210.12(A) requires AFCI protection for the branch-circuit wiring that supplies all electrical outlets and devices in specific areas in dwellings. The

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branch circuits serving which areas, locations, or rooms in dwellings are not required to have AFCI protection? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: NEC 210.12(B) provides a list of those rooms and areas in a dwelling that require AFCI protection for the branch circuits supplying electrical outlets or devices in those rooms and areas. Excluded from the list are bathrooms, garages, unfinished basements, crawl spaces, and attics. By definition, the exclusions are not considered habitable rooms.

Receptacles in areas or rooms where AFCI is not specifically required generally fall under the GFCI requirement category.

However, there is nothing in NEC 210.12that prohibits providing AFCI protection for outlets and devices other than where GFCI protection is required. In the layout of branch circuits, additional outlets or devices might very well be AFCI protected simply by connecting those areas or rooms to branch circuits that feed areas and rooms that require AFCI protection.

As time passes, more companies will manufacture dual-function AFCI/GFCI circuit breakers, making it easy for the electrician to provide AFCI and GFCI protection for all 120-volt, single-phase, 15- and 20-ampere branch circuits in a home. Dual-function AFCI/GFCI receptacles are now available. A lot of thought must be given when laying out branch circuits. Some outlets and/or branch circuits require GFCI protection; some require AFCI protection; and some require both.

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170.

When installing GFCI and AFCI circuit breakers in a panelboard, it is generally permissible to connect them to a multiwire branch circuit without verifying special considerations. (True) (False) (Select the correct answer.)

Answer: False. GFCIs and AFCIs may be connected to multiwire branch circuits however, the installer must verify that the device is listed for such an application.

An electrician has to be extremely careful when installing these devices. Some are listed for use on multiwire branch circuits where the neutral is shared; others are not so listed.

With the expanded requirements for GFCIs found in NEC 210.8 and for AFCIs found in NEC 210.12(B), the availability of dual-function GFCI/AFCI circuit breakers, and the multiplicity of various manufacturers’ listing of their products, it becomes a matter of reading the label carefully to make sure you are meeting the NEC requirements.

Remember, one of the most important sections in the NEC is 110.3(B): ―Equipment that is listed, labeled, or both shall be installed and used in accordance with any instructions included in the listing or labeling.‖* 171.

The technologies of GFCI and AFCI protection are compatible and will function correctly if installed on the same branch circuit. (True) (False) (Select the correct answer.)

Answer: True 172.

Only the receptacles in the kitchen that serve countertop surfaces are required to have AFCI protection. Other receptacles in the kitchen are not required to have AFCI pro- tection. (True) (False) (Select the correct answer.)

Answer: False. All the 15- and 20-ampere, single-phase, 125-volt outlets and devices in the kitchen are required to have AFCI protection. See NEC 210.12(B).

173.

A switch that is located inside a bedroom for an outdoor light does not require AFCI protection since the switch is not an ―outlet‖ as defined in NEC Article 100. (True) (False) (Select the correct answer.)

Answer: False. The 15- and 20-ampere, single-phase, 125-volt branch circuit that supplies outlets and devices in the bedroom are required to have AFCI protection. See NEC 210.12(B). Switches are included in the definition of ―device‖.

174.

Which of the following installations for a kitchen waste disposal that operates on a 15-ampere, 120-volt branch circuit, requires AFCI protection? (Select the correct answer.) a. The disposal operates by a switch that is installed above the kitchen counter.

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b. The disposal operates by a switch that is installed under the counter next to the disposal. c. Both (a) and (b). d. Neither (a) nor (b).

Answer: c.

Both (a) and (b). The switch is a device that is located in the kitchen.

See NEC 210.12(B).

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175.

The receptacle outlets in the garage are required to have both GFCI and AFCI protection. (True) (False) (Select the correct answer.)

Answer: False 176.

Two 125-volt receptacles on a 20-ampere, 120-volt branch circuit are installed in the laundry room. One (1) is for the washer and is within 6 ft. of the laundry sink and the other (2) is on a wall more than 6 ft. from the sink. The receptacles are required to have which of the following? (Select the correct answer.) a. GFCI and AFCI protection for both (1) and (2). b. GFCI and AFCI protection for (1) and only GFCI protection for (2). c. GFCI and AFCI protection for (2) and only AFCI protection for (1). d. GFCI and AFCI protection for (1) and only AFCI protection for (2).

Answer: a. GFCI and AFCI protection for both (1) and (2). See NEC 210.8(A)(14) and 210.12(B) where the words ―laundry area‖ is used to describe the location where GFCI and AFCI protection is required.

177.

In an old house that has 2-wire branch circuits (without an equipment grounding conductor), it is okay to install a GFCI receptacle for a microwave oven in the kitchen without also installing an equipment grounding conductor. (True) (False) (Select the correct answer.)

Answer: False. 110.3(B) and 250.114(3) * Source NFPA 70-2023.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 7: LUMINAIRES , BALLASTS, AND LAMPS TABLE OF CONTENTS Review .......................................................................................................................... 10

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REVIEW 178.

Is it permissible to install a recessed luminaire directly against wood ceiling joists when the label on the luminaire does not indicate that the luminaire is suitable for insulation to be in direct contact with the luminaire? This is a NonType IC fixture. ________________________________________________________________ _______________ Answer: No. NEC 410.116(A)(1).

179.

If a recessed luminaire without an integral junction box is installed, what extra wiring must be provided? _____________________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The luminaire must be wired with conductors having temperature ratings suitable for the temperature at the luminaire. These conductors must be installed in a raceway at least 18 in. (450 mm) long but not more than six ft (1.83 m) long. A junction box must be provided at least 1 ft (300 mm) from the luminaire. See NEC 410.117.

180.

Thermal insulation is not permitted to be installed within _________________________ in. (mm) of the side of a recessed luminaire unless the luminaire is identified for use in direct contact with thermal insulation.

Answer: 3 in. (75 mm); 3 in. (75 mm). See NEC 410.116(B).

181.

Recessed luminaires are available for installation in direct contact with thermal insulation. These luminaires are required to be marked ―Type _____________________ Answer: IC See NEC 410.116(A)(2). © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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182.

Unless specifically designed, all recessed incandescent luminaires must be provided with factory-installed _________________________________________________________ Answer: Thermal protection. See NEC 410.115(C).

183.

Plans require the installation of surface-mounted fluorescent luminaires on the ceiling of a recreation room that is finished with low-density ceiling fiberboard.

What sort of mark would you look for on the label of the luminaire? ____________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The luminaire must be marked ―Suitable for Surface-Mounting on LowDensity Cellulose Fiber-board.‖ See NEC 410.136(B).

184.

A recessed luminaire bears no marking indicating that it is ―Identified for Through-Wiring.‖ Is it permitted to run branch-circuit conductors other than the conductors that supply the luminaire through the integral junction box on the luminaire? _______________ ________________________________________________________________ _______________ Answer: No. NEC 410.64(B). Without the marking ―Identified for ThroughWiring,‖ the luminaire has not been tested for the additional heat that would be contributed by the additional conductors passing through the integral junction box on the luminaire.

185.

Fluorescent ballasts for all indoor applications must be __________________ type. These ballasts contain internal __________________ protection to protect against overheating.

Answer: Class ―P‖ Type, Integral thermal protection. See NEC 410.130(E)(1).

186.

You are called upon to install a number of luminaires in a suspended ceiling. The ceiling will be dropped approximately 8 in. (200 mm) from the ceiling joists. Briefly explain how you might go about wiring these luminaires. ___________________________ ________________________________________________________________ _______________ © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The branch-circuit wiring is installed above the suspended ceiling using standard wiring methods such as electrical metallic tubing, nonmetallic-sheathed cable, or Type MC cable. This depends on the local electrical codes. Outlet boxes are installed above the ceiling, usually on the bottom or sides of the ceiling joists. The boxes are located near the location of the suspended ceiling ―lay-in‖ luminaires. From the outlet boxes, flexible metal conduit or Type MC cable can be run to the knockouts on the luminaire. These flexible connections are not to exceed 6 ft (1.83 m) from the last point of support. The conductor temperature rating must be suitable for the temperature requirements as stated on the luminaire label. The luminaires are hoisted up and positioned so as to lay in the ―T‖ bars of the ceiling grid. The luminaires must be securely fastened to the suspended ceiling metal framing members with clips, screws, bolts, and so on, such that in the event of a fire or earthquake or similar problem, the luminaires will not fall down onto someone’s head.

187.

The Code places a maximum open-circuit voltage on lighting equipment in or on homes. This maximum voltage is (600) (750) (1000). (Select the correct answer.) Where in the NEC is this voltage maximum referenced? ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: 1000 volts. This fundamental open-circuit voltage restriction is found in NEC 410.140(B), which states that:

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(B) Dwelling Occupancies. Equipment that has an open-circuit voltage exceeding 1000 volts shall not be installed in or on dwelling occupancies.* NEC 410.135 has a further restriction stating that Equipment having an open-circuit voltage exceeding 300 volts shall not be installed in dwelling occupancies unless such equipment is designed so that there will be no exposed live parts when lamps are being inserted, are in place, or are being removed.* 188.

The letter ―E‖ in a circle on a ballast nameplate indicates that the ballast ___________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Is a high-efficiency ballast that conforms to the latest federal laws.

189.

A 120-volt lamp fluorescent ballast for two 40-watt lamps is marked 85 volt-amperes. What is the power factor of the ballast? PF = W ÷ VA _____________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: P.F. =

Wat t s 80 = = 0.94 (94%) Volt - Am peres 85

190.

Can an incandescent lamp dimmer be used to control a fluorescent lamp load? ________________________________________________________________ _______________ Answer: No. Fluorescent dimming ballasts are specially designed.

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191.

A good ―rule of thumb‖ to estimate the expected life of a motor, a ballast, or other electrical equipment is that for every _____________ C above rated temperature, the expected life will be cut in ______________________________________________________.

Answer: 10, half 192.

A post light has a 120-volt, 60-watt lamp installed. The lamp has an expected lamp life of 1000 hours. The homeowner installed a dimmer ahead of the post light and leaves the dimmer set so the output voltage is 100 volts. The lamp burns slightly (brighter) (dimmer) (select one choice) when operated at 100 volts, __________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer:  Rat ed Volt age  Expect ed Lif e =    Act ual Volt age 

13.1

 Rat ed Lif e

13.1

 120  =   Rat ed Lif e  100  = 10.896  1000 = 10.896 hours

As mentioned in the text, the above answer is only approximate because vibration, handling, cleaning, and turning the lamp off and on often shorten lamp life. The above calculation is difficult to perform without a calculator that has a ―yx‖ key to raise 1.2 to the 13.1 power. A very simple way to arrive at an acceptable answer is to multiply 1.2 by itself 13 times. For example: 120 = 1.2 100

1.2 × 1.2 × 1.2 × 1.2 × 1.2 × 1.2 × 1.2 × 1.2 × 1.2 × 1.2 × 1.2 × 1.2 × 1.2 = 10.699 Then 10.699 × 1000 = 10,699 hours.

193.

Does your community have exterior outdoor lighting restrictions?

If yes, what are they? ________________________________________________________________ ______

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________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The answer to this question depends on local ordinances.

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194.

Describe

a. fixture whip: ______________________________________________________________ _ ______________________________________________________________ _____________ Answer: A fixture whip is the common term for a flexible connection between an outlet box and a luminaire.

195.

Select the correct answer for the following statements:

a. Always match a fluorescent lamp’s wattage and type designation to the type of ballast in the luminaire. (True) (False) b. It really makes no difference what type of fluorescent lamp is used, just so the wattage is the same as marked on the ballast. (True) (False) Answer: a. True b. False 196.

Select the correct answer for the following statements.

a. When selecting a trim for a recessed incandescent luminaire, select any trim that physically fits and can be attached to the luminaire. (True) (False) b. When selecting a trim for a recessed incandescent luminaire, select a trim that the manufacturer indicates may be used with that luminaire. (True) (False) Answer: a. False b. True 197.

Have you installed LED lighting? Add comments on your experience involving LED lighting. ________________________________________________________________ _______________ Answer: There is no correct or incorrect answer to this question. The intent of the question is to solicit comments and discussion from your students. Because LED lighting is new, it will be interesting to hear what the students have to say. A few years ago, no one had heard of an LED. Requirements for installation of LED luminaires now appears in several locations of the NEC. © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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198.

Equipment grounding conductors that are permitted to be used to ground luminaires are found in NEC _______________________________________________________________ Answer: Article 410 Part V. 199.

Based on the rating or setting of the overcurrent protective device, the minimum size of a wire-type equipment grounding conductor for luminaires is found in ____________.

Answer: 250.122. * Source NFPA 70-2023.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 8: LIGHTING BRANCH CIRCUIT FOR THE FRONT BEDROOM TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the Code or the plans where necessary.

200.

Can the outlets in a circuit be arranged in different groupings to obtain the same result? Why? ________________________________________________________________ __________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Answer: Yes, because many different combinations are possible that still conform with the NEC. 201.

Is it good practice to have outlets on different floors on the same branch circuit? Why or why not? ________________________________________________________________ ____ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Though there is nothing in the NEC to prohibit this type of installation, installing outlets on different floors on the same branch circuit may make troubleshooting problems more difficult.

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202.

A good rule of thumb to follow is to never load a circuit to more than _________________ % of the branch-circuit rating.

Answer: 80% 203.

The NEC (does) (does not) require that a unit load be imposed for each receptacle outlet in a dwelling unit. (Select the correct answer.)

Answer: does not 204.

For residential wiring, not less than one 15-ampere lighting branch circuit should be provided for every ______________ ft.2 of floor area. If 20-ampere lighting branch circuits are used, provide one 20-ampere lighting branch circuit for every ______________ ft.2 of floor area.

Answer: 600 ft2, 800 ft2 205.

For this residence, what are the estimated wattages used in determining the loading of branch circuit A16?

Receptacles ______________ watts (volt-amperes) Clothes closet fixture ______________ watts (volt-amperes) Answer: Receptacles: 120 volt-amperes Closet fixture: 75 watts 206. a. What is the ampere rating of circuit A16? ______________________________________ b. What is the conductor size of circuit A16? ______________________________________ Answer: a. 15 amperes b. 14 AWG 207.

The NEC requires what type of unique protection for all 120-volt, 15- and 20-ampere branch-circuits supplying outlets or devices in bedrooms of residential homes? In which section of the NEC is this requirement found? _______________________________ Answer: The NEC 210.12(B) provides a list of rooms where AFCI protection of the branch circuit is required. The outlets or devices supplied by several branch circuits are required to have either AFCI or GFCI protection. Circuit A-16 feeds receptacle outlets and lighting outlets. An AFCI circuit breaker in Panel A will provide arc-fault protection for all the outlets and devices connected to this branch circuit.

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208.

How many and what type of receptacles are connected to circuit A16? _______________ ________________________________________________________________ ________________ Answer: Five split-wired receptacles in the bedroom and one weatherproof receptacle on the outside, for a total of six receptacles.

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209.

What main factors influence the choice of wall boxes? _____________________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: Factors that need to be considered are the size and number of conductors, the number of wiring devices, cable clamps, fixture studs, hickeys, and splices. See NEC 314.16.

210.

How is a metal wall box grounded? _______________________________________________ ________________________________________________________________ ________________ Answer: By installing Type MC cable, or nonmetallic-sheathed cable containing an equipment grounding conductor that is connected to the metal wall box. EMT will also provide an adequate equipment ground.

211.

What is a split-wired receptacle? _________________________________________________ ________________________________________________________________ ________________ Answer: A device having one receptacle that is connected directly to the ―hot‖ wire that is on continuously. The other receptacle is connected to the wire that is controlled by the switch. Split-wired receptacles may also be used for individual circuiting of each receptacle.

212.

Is it recommended that the switched portion of an outlet be mounted toward the top or the bottom? Why? ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: It is recommended that the switched portion is mounted at the bottom so that any lamp cord plugged into the switched section does not hang in front of the unswitched portion. This is not a Code requirement.

213.

The following problems pertain to luminaires in clothes closets.

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a. Does the Code permit bare incandescent lamps to be installed in porcelain key-less or porcelain pull-chain lampholders? __________________________________________ b. Does the Code permit bare fluorescent lamp luminaires to be installed? __________ ______________________________________________________________ ______________ c. Does the Code permit pendant lampholders to be installed? _____________________ ______________________________________________________________ ______________ d. What is the minimum clearance from the storage area to surface-mounted incandescent luminaires? ____________________________________________________ e. What is the minimum clearance from the storage area to surface-mounted fluorescent luminaires? ______________________________________________________ f. What is the minimum distance between recessed incandescent or recessed fluorescent luminaires and the storage area? _________________________________ g. Define the ―clothes closet storage space.‖ ______________________________________________________________ _____________ ______________________________________________________________ _____________ ______________________________________________________________ _____________ ______________________________________________________________ _____________ ______________________________________________________________ _____________ ______________________________________________________________ _____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

h. If a clothes hanging rod is installed where there is access from both sides, such as might be found in a large walk-in clothes closet, define the storage area under that rod. ______________________________________________________________ _____________ ______________________________________________________________ _____________ ______________________________________________________________ _____________ ______________________________________________________________ _____________ ______________________________________________________________ _____________ ______________________________________________________________ _____________ Answer: See NEC 410.16. a. No b. Yes c. No d. 12 in. (300 mm) e. 6 in. (150 mm) f. 6 in. (150 mm) g. On walls where there is a rod, 24 in. (600 mm) from that wall under the rod and downward to the floor. On walls where there is a shelf above the rod, 12 in. (300 mm) from the wall or the width of the shelf, whichever is greater, upward to the ceiling. See diagrams in text and see Figure NEC 410.2 in Article 410 of the NEC. h. The area 12 in. (300 mm) on either side of the rod downward to the floor

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

214.

How many switches are in the bedroom circuit, what type are they, and what do they control? ________________________________________________________________ _______ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: One SP switch for the closet light One SP switch for the receptacles One SP switch for the paddle fan One speed control switch for the paddle fan motor 215.

The following is a layout of the lighting circuit for the Front Bedroom. Using the cable layout shown in Figure 8-7, make a complete wiring diagram of this circuit. Use colored pencils or pens.

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115

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: Wiring diagram for Front Bedroom lighting circuit

216.

When planning circuits, what common practice is followed regarding the division of loads? ________________________________________________________________ ________ ________________________________________________________________ _______________ Answer: Loads are divided as evenly as possible among circuits.

217.

The Code uses the terms watts, volt-amperes, kW, and kVA. Explain their significance in calculating loads. ______________________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: On an AC circuit, the only time that watts equal volt-amperes, or when kW equals kVA, is in the case of a pure resistive circuit (100% power factor). If wattage values are used for calculations for other than resistive loads (such as a motor load), it is likely that a current draw smaller than the actual value will be calculated. Using VA and kVA values ensures that the actual current draw will be obtained.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

218.

How many 14 AWG conductors are permitted in a device box that measures 3 in. 2 in. 2 3 4 in.? ________________________________________________________________ ______ Answer: Seven. The number of conductors, cable clamps, wiring devices, and so forth, must be considered.

219.

A 4 in. 1 1 2 in. octagon box has one cable clamp and one luminaire stud.

How many 14 AWG conductors are permitted? _______________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: See NEC 314.16 and Table 314.16(A).

Box

7 conductors

Less one for clamp

–1

Less one for stud

–1 ___ 5

Total

Table 314.16(A) is for metal boxes that are manufactured in standard sizes. For nonmetallic boxes, NEC 314.16(A)(2) requires the manufacturer to mark the box with its cubic inch volume. Table 314.16(B) shows the volume that is required for various size conductors. The minimum size of nonmetallic boxes is determined by adding the volume allowance for conductors, internal cable clamps, support fittings, device or equipment fill and equipment grounding conductors.

Note: Depending on the location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 9: LIGHTING BRANCH CIRCUIT FOR THE MASTER BEDROOM

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the Code or the plans where necessary.

220.

What circuit supplies the Master Bedroom?

________________________________________________________________ _______________ Answer: A19 221.

What unique type of electrical protection is required for all 120-volt, singlephase, 15- and 20-ampere branch circuits supplying outlets and/or devices in certain habitable rooms and areas in new dwellings? ________________________________________________________________ _______________ Where in the NEC is this requirement found? ______________________________________ Answer: NEC 210.12(B) lists the areas within a dwelling unit that require AFCI protection. This protection must be supplied by one of the methods described in 210.12(A)(1) through (A)(6).

Circuit A-19 feeds receptacle outlets and lighting outlets. An AFCI circuit breaker in Panel A will provide arc-fault protection for the all outlets and devices connected to this circuit.

222.

What type of receptacles are provided in this bedroom? How many receptacles are there? ________________________________________________________________ ________ Answer: Four split-wired receptacles 223.

How many ceiling outlets are included in this circuit? _____________________________ ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: One ceiling fan/light outlet plus two closet ceiling outlets, for a total of three outlets 224.

What wattage for the clothes closet luminaires was used for estimating their contribution to the load on the branch circuit? ____________________________________ Answer: 75 watts each; total 150 watts (150 VA) 225.

What is the estimated current draw for the ceiling fan/light? ________________________ Answer: 2 amperes 226.

What is the estimated load in volt-amperes for the circuit supplying the Master Bedroom? ________________________________________________________________ ______ Answer: 1140 volt-amperes 227.

Which is installed first, the switch and outlet boxes or the cable runs? ______________ ________________________________________________________________ _______________ Answer: Usually, the boxes are installed first. Make sure that the box is large enough for the size and number of conductors, wiring devices, clamps, luminaire studs, and so on. Some electricians prefer to install the cables first, then install the boxes. This gives a better ―feel‖ for the number of conductors at a particular box location and the size and type of box needed.

228.

How many conductors enter the ceiling fan/light wall box? ________________________ ________________________________________________________________ _______________ Answer: Five, not counting equipment grounding conductors if the wiring is a cable-type method.

229.

What type and size of box may be used for the ceiling fan/light wall box? ___________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: 4 in. square, 2 18 -in. deep with 2-gang raised plaster ring. See Table 314.16(A) and Figure 2–37 in Chapter 2 for other possibilities.

230.

What type of covers are used with 4 in. square outlet boxes? _______________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Single- and 2-gang raised plaster covers and 3-in. round opening covers 231.

The branch circuit layout begins at the outlet box for the outside receptacle. Would you begin the branch circuit wiring at another point? If so, explain where you would start the branch circuit and why. ________________________________________________ ________________________________________________________________ _______________ Answer: Note: There is no one correct answer to this question. Much depends on how the electrician elects to run the cables. The instructor is urged to use this question for discussion.

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232.

How high are the receptacles mounted above the finished floor in this bedroom? ________________________________________________________________ _______________ Answer: 12 in. (300 mm) to center from finish floor 233.

Approximately how far from the bedroom door is the first receptacle mounted? (See the plans.) ________________________________________________________________ _____ ________________________________________________________________ _______________ Answer: Approximately 2 12 ft (750 mm) 234.

What is the distance from the finished floor to the center of the wall switches in this bedroom? ________________________________________________________________ _____ Answer: 46 in. (1.15 m) to center from finish floor 235.

The Master Bedroom features a sliding glass door. For the purpose of providing the proper receptacle outlets, answer the following statements. (Select the correct answer.) 

Sliding glass panels are considered to be wall space.

(False)

(True)



Fixed panels of glass doors are considered to be wall space.

(False)

(True)

Answer: See NEC 210.52(A)(2). Sliding glass panels are considered to be wall space.

Answer: False Fixed panels of glass doors are considered to be wall space.

Answer: True 236.

What type of receptacle will be installed outdoors, just outside of the Master Bedroom? ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

________________________________________________________________ _______________ Answer: A tamper-resistant, weather-resistant GFCI receptacle protected by a weatherproof cover. See NEC 210.8(A)(3), 406.12 and 406.9.

237.

Show your calculations of how to select a proper wall box for the clothes closet luminaire switch. Keep in mind that the available space between the wood casings is small. See Figure 9-1. ___________________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: 1. Circuit conductors

5

2. Equipment grounding conductors (count one only) 1 3. Two switches on one yoke

2

4. One cable clamp

1 _____

Total

9

Refer to Tables 314.16(A) and (B), and to Figure 2–37 in Chapter 2 for an example of a suitable device box and to Figure 5–28 for an example of a wiring device with more than one switch on a single switch yoke.

A device box 3 × 2 × 3 12 ; a 4 × 4 × 1 12 square box with a 2-gang or single-gang raised cover 238.

When an outlet box is to be installed to support a ceiling fan, how must it be marked? ________________________________________________________________ _______________ Answer: The box must be listed and must be marked ―Acceptable for Fan Support.‖ See NEC 314.27(C).

239.

The following is a layout of the lighting circuit for the Master Bedroom.

Using the cable layout shown in Figure 9-1, make a complete wiring diagram of this circuit. Use colored pencils or pens.

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124

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: Wiring diagram for Master Bedroom lighting

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

240.

Connect the 4-wire cable, fan, light, fan speed control, and light switch.

Refer to 200.7 to review the permitted use of the white conductor in the cable.

Answer: Connect the 4-wire cable, fan, light, fan speed control, and light switch.

Refer to 200.7 of the NEC to review the permitted use of the white conductor in the cable.

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

241.

What is the width of a standard 2-gang wall plate?

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: 4 9 16 in. (116 mm)

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

242.

Is a standard electronic dimmer permitted to be used to control the speed of a fan motor? ________________________________________________________________ ______ Answer: No. Always read the instructions that are furnished with the dimmer and/or speed control to find out its specific applications.

243.

Outlet boxes that pass the tests at a qualified electrical testing laboratory for the support of ceiling-suspended (paddle) fans are listed and marked ―Acceptable for Fan Support.‖ When roughing-in the electrical wiring for a new home, this type of outlet box must be installed wherever it is possible to install a ceiling-suspended (paddle) fan in a habitable room. List some locations in homes that you consider likely to require ceiling-suspended (paddle) fan support rated ceiling outlet boxes. ___________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: See NEC 314.27(C). Kitchens, family rooms, dining rooms, parlors, libraries, dens, sun rooms, bedrooms, recreation rooms, or similar rooms. Ceiling boxes close to walls would not be likely locations for a ceiling-suspended (paddle) fan. * Source NFPA 70-2023.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 10: LIGHTING BRANCH CIRCUIT—BATHROOMS , HALLWAY TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW 244.

List the number and types of switches and receptacles used in Circuit A14.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Switches: ___________________________________________________________________ ___ Receptacles: ___________________________________________________________________ Answer: Two 3-way switches in hall One single-pole switch in Master Bathroom One single-pole switch in hall bathroom One receptacle in the hall Note: The receptacles in the bathrooms are connected to separate 20-ampere branch circuits A22 and A23 as required by NEC 210.11(C)(3).

245.

There is a 3-way switch in the bedroom hallway leading into the living room. Show your calculation of how to determine the box size for this switch. The box contains cable clamps.

Answer: a.

7

c.

Circuit conductors Grounding conductor (count one only) Three-way switch

d.

One cable clamp

1 ____

Total

11

b.

1 2

Select a box capable of accommodating eleven 14 AWG conductors.

246.

What wattage was used for each vanity luminaire to calculate the estimated load on Circuit A14? ________________________________________________________________ ___ Answer: 200 watts 247.

What is the current draw for the answer given in problem 3?

________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: I

W 200   1.66 amperes E 120

248.

Exposed non-current-carrying metallic parts of electrical equipment must connect to an EGC if installed within ________________ ft. (________________ m) vertically or ________________ ft. (________________ m) horizontally of bathtubs, plumbing fixtures, pipes, or other grounded metal work or grounded surfaces.

Answer: 8 ft (2.5 m) vertically; 5 ft (1.5 m) horizontally. See NEC 250.110.

249.

What color are the faceplates in the bathrooms? Refer to the specifications. ________________________________________________________________ _______________ Answer: Ivory 250.

Most appliances of the type commonly used in bathrooms, such as hair dryers, electric shavers, and curling irons, have 2-wire cords. These appliances are _______________ insulated or _______________ protected.

Answer: Double. Immersion detector circuit interrupter protected.

251.

a. _______________ The NEC in Section _______________ requires that all receptacles in bathrooms be _______________ protected.

b.

The NEC in Section _______________ requires that all receptacles required by 210.52(D) be connected to one or more separate 20-ampere branch circuits that serve no other outlets.

c.

The NEC in Section _______________ permits the required 20-ampere branch circuit for bathroom receptacles to supply more than one bathroom.

Describe the condi-tion that would allow this circuit to supply receptacles in more than one bathroom.

______________________________________________________________ ______________ ______________________________________________________________ ______________ d.

The NEC in Section _______________ permits other electrical equipment to be connected to the required 20-ampere branch circuit for bathroom receptacles, but only if the branch circuit supplies a single bathroom and the other equipment is located in that same bathroom.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

e.

The NEC in Section _______________ prohibits mounting receptacles in bathrooms face-up in the countertops and work surfaces near basins.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: a. NEC 210.8(A)(1), GFCI protected b. NEC 210.11(C)(3) c. NEC 210.11(C)(3), Bathroom branch circuits can supply receptacles in more than one bathroom if the circuits only supply receptacles. If the circuit will supply a light or fan, then the branch circuit is limited to supplying only a single bathroom. d. NEC 210.11(C)(3) Exception e. NEC 406.5(E). Receptacle outlet assemblies listed for the application are permitted to be installed in the countertop. Also read 210.52(D).

252.

Hanging luminaires must be kept at least _______________ ft. (_______________ m) from the edge of the tub as measured horizontally. In bathrooms with high ceilings, where the hanging luminaire is installed directly over the tub, it must be kept at least _______________ ft. (_______________ m) above the edge of the tub.

Answer: 3 ft (900 mm); 8 ft (2.5 m) 253.

The following is a layout of a lighting circuit for the bathroom and hallway.

Using the cable layout shown in Figure 10-1, make a complete wiring diagram of this circuit. Use colored pencils or pens.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

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Answer:

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

254.

Circle the correct answer as to whether a receptacle outlet is required in the following hallways.

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134

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: See NEC 210.52(H). a. Not required b. Required c. Not required d. Required e. Not required

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 11: LIGHTING BRANCH CIRCUIT—FRONT ENTRY, PORCH, P OST LIGHT, UNDERGROUND W IRING TABLE OF CONTENTS Review .......................................................................................................................... 10

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

REVIEW 255. a. How many circuit wires enter the entry ceiling box? ___________________________ b. How many equipment grounding conductors enter the entry ceiling box? _________ Answer: a. Nine b. Four 256.

Assuming that an outlet box for the entry ceiling has a fixture stud but has external cable clamps, what size box could be installed? Show calculations for both metal and nonmetallic boxes. ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: Circuit conductors (14 AWG)

9

Add one for luminaire stud

1

Add equipment grounding wires

1 _____

Total

11

Some possibilities are a 4" octagonal, 2⅛" deep box or a 4" square, 2⅛" deep box with plaster ring. There are other possibilities. See Table 314.16(A), which is to be used for metal boxes only.

Using a nonmetallic box, refer to Table 314.16(B) and find that 14 AWG conductors require a volume of 2 cubic inches. The volume count is therefore

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

based on 11 × 2 = 22, which includes the conductors, fixture stud, and equipment grounding conductors.

NEC 314.16(A)(2) states that nonmetallic boxes shall have their volume durably and legibly marked on the box. Most manufacturers’ catalogs have tables that show the cubic inch volume and maximum number of conductors permitted in various size boxes.

NEC 314.16(B)(1), Exception states that the small fixture (luminaire) conductors do not have to be counted.

257.

How many receptacle outlets and lighting outlets are supplied by Circuit A15? Receptacle outlets: ______________________ Lighting outlets: ______________________ Answer: Receptacles, Three; Lighting, Six 258.

Outdoor luminaires directly exposed to the weather must be marked as (Select the correct answer.) a. suitable for damp locations. b. suitable for dry locations only. c. suitable for wet locations.

Answer: c. Suitable for wet locations 259.

Make a material list of all types of switches and receptacles connected to Circuit A15. ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer:

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

One tamper-resistant receptacle One weatherproof and tamper resistant GFCI receptacle One tamper-resistant receptacle on post light (GFCI protection on supply side) Three single-pole switches Four 3-way switches

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

260.

From left to right, facing the switches, what do the switches next to the front door control?

1. ______________________________________________________________ _____________ 2. ______________________________________________________________ _____________ 3. ______________________________________________________________ _____________ 4. ______________________________________________________________ _____________ 5. ______________________________________________________________ _____________ Answer: 1. 3-way switch for lighting above basement stair landing and at bottom of stairs 2. Upper, Single pole switch for weatherproof receptacle on porch, 3. Lower, Single pole for post light 4. 3-way switch for porch luminaire and two luminaires on front of garage 5. 3-way switch for entry ceiling luminaire In some instances, the electrician might want to discuss the switch arrangement with the homeowner to find out whether there are any preferences.

261.

Who is to select the entry ceiling luminaire? ______________________________________ Answer: Homeowner 262.

Which of the following wiring methods is suitable for direct burial to the post light? (Type NM Cable) (Type UF Cable) (Select the correct answer.)

Answer: Type UF Cable 263.

When installing the wiring for a doorjamb switch, the best choice is (Select the correct answer.) a. run the supply conductors to the doorjamb box, then run the switched conductors to the luminaire. b. run the supply conductors to the outlet box where the luminaire is to be installed, then run the switch loop conductors to the doorjamb box.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: b. Run the supply conductors to the outlet box where the luminaire is to be installed, then run the switch loop conductors to the door jamb box. Remember that the wiring space in this type of special door jamb box is very limited. The size and maximum number of conductors permitted in the box must be in conformance to the listing and instructions furnished with the door jamb switch. Remind the student that a low-voltage control may be substituted for the linevoltage switch as discussed in the text. You may want them to draw out the control circuit to be certain that they understand the concept.

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264.

The following layout is for Lighting Circuit A15, the entry, porch, post light, and front garage lights. Using the cable layout shown in Figure 11-1, make a complete wiring diagram of this circuit. Use colored pencils to indicate the color of the conductors’ insulation.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer:

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NFC 404.2(C).

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 12: LIGHTING BRANCH CIRCUIT AND SMALL-APPLIANCE CIRCUITS FOR THE KITCHEN

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142

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the NEC or the plans in the back of this text if desired.

265.

If everything on Circuit B7 were turned on, what would be the total current draw according to the estimate? ________________________________________________________________ ____________ Answer: I=

VA 480 = = 4.0 amperes E 120

266.

From what panelboard does the kitchen lighting circuit originate? What size conductors are used? ________________________________________________________________ __ ________________________________________________________________ ____________ Answer: Panelboard B; 14 AWG 267.

How many luminaires are connected to the kitchen lighting circuit?

________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: Five. This does not includes the light in the microwave/range hood.

268.

What color temperature (K rating) lamps are recommended for residential installations? ________________________________________________________________ ____________ ________________________________________________________________ ____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: Deluxe warm white (WWX), or warm white (WW), or deluxe cool white (CWX)

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

269.

a. What is the minimum number of 20-ampere small-appliance circuits required for a kitchen according to the Code? ______________________________________________

b. How many are there in this kitchen? __________________________________________ Answer: a. Two b. Three, plus the separate 20-ampere circuit for the refrigerator.

270.

How many receptacle outlets are provided in the kitchen? __________________________ Answer: Eleven including the receptacle for the microwave oven/hood fan 271.

What is meant by the term split-wired receptacles? ________________________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: A receptacle to which two circuits may be connected. Each outlet of the receptacle is capable of being connected to a separate circuit. Also, part of the split-wired receptacle may be switch controlled.

272.

Duplex receptacles connected to the 20-ampere, small-appliance branch circuits in kitchens and dining rooms: (Select the correct answer.) a. may be rated 15 amperes. b. must be rated 15 amperes. c. may be rated 20 amperes. d. must be rated 20 amperes.

(True) (True) (True) (True)

(False) (False) (False) (False)

Answer: See Table 210.21(B)(3). a. True

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

b. False c. True d. False

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

273.

In kitchens, a receptacle must be installed at each counter space _________________ in. or wider.

Answer: 12 in. (300 mm). See NEC 210.52(C)(1).

274.

How many circuit conductors enter the box

a. where the range hood will be installed? ____________________________________ b. in the ceiling box over which the track light will be installed? _________________ c. at the switch location to the right of the sliding door? _______________________ Answer: a. Two, plus one equipment grounding conductor b. Five, plus two equipment grounding conductors c. Eleven, plus four equipment grounding conductors 275.

How much space is there between the countertop and upper cabinets? ___________ Answer: 18 in. (450 mm). Refer to Plan 4 of 10.

276.

Where is the speed control for the range hood fan located? ______________________ Answer: On the range hood unit 277.

Who is to furnish the range hood? ______________________________________________ Answer: Electrical contractor. See Specifications.

278.

List the appliances in the kitchen that must be electrically connected. _______________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: Built-in oven, built-in countertop cooking unit, dishwasher, food waste disposer, microwave oven/range hood fan/light 279.

Complete the wiring diagram, connecting feed-through GFCI 2 to also protect receptacle 1, both to be supplied by Circuit A1. Connect feed-through GFCI 3 to also protect receptacle 4, both to be supplied by Circuit A2. Use colored pencils or markers to show proper color. Assume that the wiring method is EMT, where more freedom in the choice of insulation colors is possible.

Answer: Note: In the diagram, the equipment grounding terminals on the receptacles are shown as being connected to ground. This is assumed to be accomplished by the No. 6-32 screws that secure the receptacles to the metal device boxes. These receptacles have the automatic self-grounding feature. If the wall boxes are nonmetallic, then the equipment grounding terminals on the

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

receptacles must be connected to the equipment grounding conductor(s) in the box. The text covers this in detail.

280.

Each 20-ampere, small-appliance, branch-circuit load demand shall be determined at __________________________. (Select the correct answer.) a. 2400 volt-amperes b. 1500 volt-amperes c. 1920 volt-amperes Answer: b. 1500 volt-amperes. See NEC 220.52(A).

281.

a. Does the NEC permit the receptacle for the refrigerator to be supplied by one of the required 20-ampere, small-appliance branch circuits? Yes ______________________ No ______________________ Section ______________________.

b. Does the NEC permit the receptacle for the refrigerator to be supplied by an individual branch circuit? Yes ____________________ No ____________________ Section ____________________ c. What is the practice in your area?

Answer: a. Yes. NEC 210.52(B)

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

b. Yes. NEC 210.52(B), Exception No. 2. c. The answer depends on local custom. The instructor is encouraged to get into a discussion on the pros and cons of how to supply the refrigerator receptacle.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

282.

a. The Code requires a minimum of two small-appliance circuits in a kitchen.

Is it permitted to connect a receptacle in a dining room to one of the kitchen small-appliance circuits? _________________________________________________

What Code section applies to this situation? ________________________________ b. Are outdoor weatherproof receptacles permitted to be connected to a 20ampere, small-appliance circuit? __________________________________________________ c. Receptacles located above the countertops in the kitchen must be supplied by at least _________________ 20-ampere, small-appliance circuits.

Answer: a. Yes. NEC 210.52(B)(1). b. No. NEC 210.52(B)(2). c. Two. NEC 210.52(B)(3).

283.

According to 210.52, no point along the floor line is permitted to be more than ____________________ ft. (____________________ m) from a receptacle outlet. A receptacle must be installed in any wall space ____________________ ft. (____________________ m) wide or greater.

Answer: 6 ft (1.8 m); 2 ft (600 mm). See NEC 210.52(A)(1) and (2).

284.

The Code states that in multiwire circuits, the screw terminals of a receptacle must not be used to splice the neutral conductors. Why? ________________________________________________________________ ________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: Removing the wires from the receptacle’s white terminal results in an open neutral. In a multiwire circuit, a high voltage can result. See Chapter 17 for a complete explanation of multiwire circuits. See NEC 250.148 and 300.13(B).

285.

Electric fans produce a certain amount of noise. It is possible to compare the noise levels of different fans prior to installation by comparing their ________________ ratings.

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Answer: Sone 286.

Is it permitted to connect the white grounded circuit conductor to the equipment grounding terminal of a receptacle? ______________________________________________ Answer: No. See NEC 250.142(A) and (B) and 406.4(B)

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

287.

What is unique about 120-volt appliances that are 2-wire, cord-and-plug connected instead of being 3-wire, cord-and-plug connected? ________________________________ ________________________________________________________________ ________________ Answer: Appliances rated 120 volts that are equipped with a 3-wire cord are grounded by the equipment grounding conductor in the 3-wire cord. Appliances equipped with a 2-wire cord are ―double-insulated‖ according to UL standards.

Both insulations would have to fail for an electrical shock hazard to exist.

288.

a. All 125-volt, single-phase, 15- and 20-ampere receptacles installed in a kitchen must be GFCI-protected. (True) (False) (Select the correct answer.)

b. All 125-volt, single-phase, 15- and 20-ampere receptacles installed within 6 ft.

(1.8 m) from the top inside edge of the bowl of a wet bar, laundry, utility, or similar sink must be GFCI-protected. (True) (False) (Select the correct answer.)

Answer: a. True, NEC 210.8(A)(6). b. True, NEC 210.8(A)(7).

289.

All branch circuits supplying receptacle outlets in the kitchen are required to be AFCI-protected. (True) (False) (Select the correct answer.)

Answer: True. 210.12(A) 290.

The kitchen features a sliding glass door. For the purpose of providing the proper receptacle outlets, answer the following statements true or false. a. Sliding glass panels are considered to be wall space. ___________________________ b. Fixed panels of glass doors are considered to be wall space. ____________________ Answer: a. False. b. True. Fixed glass panels are considered to be wall space for the purposes of locating receptacle outlets. NEC 210.52(A)(2).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

291.

The following is a layout for the lighting circuit for the Kitchen. Complete the wiring diagram using colored pens or pencils to show the conductors’ insulation color.

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154

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer:

292.

a. In your area, does the electrical inspector require that an individual branch circuit be installed for the refrigerator? (Yes) (No) (Select the correct answer.)

b. In your area, does the electrical inspector require that a single receptacle be installed for the refrigerator? (Yes) (No) (Select the correct answer.)

Answer: The answers to both a and b could be yes or no, depending on the local area.

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 13: LIGHTING BRANCH CIRCUIT FOR THE LIVING ROOM TABLE OF CONTENTS Review .......................................................................................................................... 10

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

REVIEW Note: Refer to the NEC or the plans in the back of this text if desired.

293.

To what circuit is the living room connected? ______________________________________ Answer: B17 294.

How many receptacles are connected to this circuit? _______________________________ Answer: Nine 295.

a. How many wires enter the switch box at the 4-way switch location? _____________

b. What type and size of box may be installed at this location? _____________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: a. 6 circuit conductors plus two equipment grounding conductors. b. Circuit conductors

6

Equipment grounding conductors

1

Clamps

1

Switch

2 _____

Total

10

Select a box that can hold ten 14 AWG conductors. See NEC 314.16 and Tables 314.16(A), NEC 314.16(B) and 404.2(C).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

296.

How many wires must be run between an incandescent lamp and its dimmer control? ________________________________________________________________ ________________ Answer: Two 297.

Complete the wiring diagram for the dimmer and lamp.

Answer:

298.

Is it possible to dim standard fluorescent ballasts? ________________________________ Answer: No. Special dimming ballasts are required. Some compact fluorescent lamps have an integrated circuit that makes the lamp dimmable with a standard wall dimmer.

299.

a. How many wires must be run between a dimming-type fluorescent ballast and the dimmer control? ____________________________________________________________

b. Is a switch needed in addition to the dimmer control? __________________________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

______________________________________________________________ ______________ Answer: a. Three b. Not necessarily. Most dimmer units have a switch built in. It may be desirable to leave the dimmer set at a certain light level and use an ON–OFF switch.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

300.

Explain why fluorescent lamps that have the same wattage rating draw different current values. ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: The current ratings must be checked for various types of ballasts because the current draw depends on the power factor of the ballast-lamp combination. The lower the power factor rating, the higher the current draw.

301.

What is the total current consumption of the track lighting and recessed luminaires above the fireplace as shown in Table 13-1? Show your calculations.

Answer: I=

VA 350 = = 2.92 amperes E 120

302.

How many television outlets are provided in the Living Room? __________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: Three 303.

Electronic dimmers of the type sold for residential use (shall) (shall not) be used to control fluorescent luminaires. These dimmers (are) (are not) intended for speed control of small motors. (Select the correct answers.)

Answer: Shall not; are not. Always read the information furnished with the dimmer and/or speed control to see for which application it is intended to be used.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

304.

A layout of the outlets, switches, dimmers, track lighting, and recessed luminaires is shown in the following diagram. Using the cable layout of Figure 131, make a complete wiring diagram of this circuit. Use colored pencils or marking pens to indicate conductors.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer:

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

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305.

Prepare a list of television outlets, telephone outlets, and wiring devices shown on the plans and cable layout for the living room area. Include the number of each type present. ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: W.P. GFCI receptacle

1

Split-wired receptacles

8

Standard type receptacles

1

Three-way switches

3

Four-way switches

1

Single-pole dimmer switches Television outlets

2 3

306.

The Living Room features a sliding glass door. For the purpose of providing the proper number of receptacle outlets, answer the following statements true or false. a. Sliding glass panels are considered wall space. ______________________________ b. Fixed panels of glass doors are considered wall space. _______________________ Answer: a. False, NEC 210.52(A)(2)(2).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

b. True, NEC 210.52(A)(2)(2).

307.

Must track lighting always be fed (connected) at one end of the track? ____________ ________________________________________________________________ _____________ Answer: No. Track lighting may be fed at the ends or at any point on the track, using the proper fittings.

308.

May a standard electronic dimmer be used to control low-voltage lighting that incorporates a transformer, or for controlling the speed of a ceiling fan motor?

Yes _________________ No _________________ Answer: No, unless the dimmer is specifically marked for this application. The transformer and dimmer could be seriously damaged because of overheating.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

309.

Does the Code permit cutting lengths of portable track lighting to change their length? Yes _________________ No _________________ Answer: No. This is not covered in the NEC but is covered in UL Standard 153.

310.

Why should the power be turned off when hooking up a dimmer? __________________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ Answer: There are two good reasons: (1) because of the possibility of electrical shock and (2) because the dimmer may be damaged if the connections are ―bounced‖ (make and break rapidly) when making the hook-up.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 14: LIGHTING BRANCH CIRCUIT FOR THE STUDY/BEDROOM TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the NEC or the plans in the back of this text if desired.

311.

Based on the total estimated load calculations, what is the current draw on the Study/Bedroom circuit? ________________________________________________________ Answer: I = VA = 1125 = 9.4 amperes E

120

312. a. The Study/Bedroom is connected to circuit __________________________________. b. The minimum conductor size for this circuit is _______________________________.

Answer: a A21 b. 14 AWG © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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313.

a. What unique type of electrical protection is required for all 120-volt, singlephase, 15- and 20-ampere branch circuits for most habitable rooms and areas in new homes?

______________________________________________________________ ____________ b. What section of the Code covers this kind of protection? _____________________ Answer: Arc-fault circuit-interrupter protection. See NEC 210.12(A).

314.

Why is it necessary to install a receptacle in the wall space leading to the bedroom hallway? ________________________________________________________________ _____ ________________________________________________________________ ______________ ________________________________________________________________ ______________ Answer: The Code requires a receptacle outlet to be provided in any wall space 2 ft (600 mm) wide or greater, NEC 210.52(A)(2)(1).

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315.

Show the calculations needed to select a properly sized box for the receptacle outlet mentioned in problem 4. Nonmetallic-sheathed cable is the wiring method. ________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ Answer: Refer to Tables 314.16(A) and (B).

Circuit conductors (in three cables)

8

Equipment grounding conductors (three, but count as one)

1

One receptacle (count as two conductors)

2

Cable clamps (two, but count as one for each type)

1 _____

Total

12

Select a box suitable for twelve 14 AWG conductors, such as a 4 4 2⅛ in. square box. Install proper single-gang raised cover as required.

316.

Show the calculations necessary to select a properly sized box for the receptacle outlet mentioned in problem 4. The wiring method is EMT, usually referred to as ―thin-wall conduit.‖ Does the different wiring method type change the size of outlet box required? ________________________________________________________________ ______________ ________________________________________________________________ ______________

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________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ Answer: Refer to Table 314.16(A) and (B).

Circuit conductors (in three conduits)

8

Equipment grounding conductors (none, EMT serves as equipment grounding conductor)

0

One receptacle (count as two conductors)

2

Cable clamps (none)

0 _____

Total

10

Select a box suitable for ten 14 AWG conductors. Install proper singlegang raised cover as required.

317.

Prepare a list of all wiring devices used in Circuit A21.

________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________

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________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ Answer: Split-wired receptacles

4

Regular type receptacles

2

Single-pole switches

2

Three-way switches

2

Special paddle fan/light control

1

318.

For the valence lighting, the typical type of luminaires used are ___________________ ________________________________________________________________ ______________ Answer: Fluorescent.

319.

Are there other types of lighting that could be utilized for the valence lighting other than the type mentioned in this text? ___________________________________________.

Answer: LED or Incandescent lamps

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

320.

Using the cable layout shown in Figure 14-1, make a complete wiring diagram of Circuit A21. Use colored pencils or pens.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: Using the cable layout shown in Figure 14-1, make a complete wiring diagram of Circuit A21. Use colored pencils or pens.

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C). _______________________________.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 15: DRYER O UTLET, LIGHTING, AND RECEPTACLE CIRCUITS FOR THE LAUNDRY, POWDER ROOM, REAR ENTRY HALL, AND ATTIC TABLE OF CONTENTS Review .......................................................................................................................... 10

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REVIEW Note: Refer to the Code or plans where necessary.

321.

List the switches, receptacles, and other wiring devices that are connected to Circuit B10. ________________________________________________________________ ___ ________________________________________________________________ ______________ ________________________________________________________________ ______________ Answer: Single-pole switches

4

Single-pole switch with pilot light 1 Three-way switches Receptacles—regular 322.

2 1

a. Fill in the blank spaces. At least ____________ 120-volt receptacle(s) must be installed in a bathroom within ____________ in. of the sink and must be on the wall ____________ to the sink. The receptacle must be ____________ protected.

b. A separate (15-) (20-)ampere branch circuit must supply the receptacle(s) in bathrooms and (shall) (shall not) serve other loads. If a separate 20-ampere branch circuit serves a single bathroom, then that circuit (is permitted) (is not permitted) to supply other loads in that bathroom. (Select the correct answers.)

Answer: a. One, 36, or partition that is adjacent, GFCI. See NEC 210.8(A)(1), 210.52(D) and 406.5(G(1)). b. 20, shall not, is permitted. See NEC 210.11(C)(3). Note that the Exception to this section permits a 20-ampere branch circuit that supplies only one bathroom to supply all the equipment in the bathroom in accordance with NEC 210.23(A)(1) and (A)(2). This includes equipment such as luminaires and exhaust fans.

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323.

What special type of switch is controlling the attic lights? ________________________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ Answer: A single-pole switch that has an integral pilot light 324.

When installing cables in an accessible attic along the top of the floor joists ____________________________ must be installed to protect the cables.

Answer: Guard strips. See NEC 334.23, 320.23(A).

325.

The total estimated volt-amperes for Circuit B10 has been estimated to be 1144 volt-amperes. How many amperes is this at 120 volts? ______________________ Answer: I = VA = 1144 = 9.5 amperes E

120

326.

If an attic is accessible through a scuttle hole, guard strips are installed to protect cables run across the top of the joists only within (6 ft. [1.8 m]) (12 ft. [3.7 m]) of the scuttle hole. (Select the correct answer.)

Answer: 6 ft (1.8 m) See NEC 320.23(A).

327.

What section(s) of the Code refers (refer) to the receptacle required for the laundry equipment? State briefly the requirements. ________________________________________________________________ ______________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ Answer: NEC 210.8(A)(8) NEC 210.8(A)(11) NEC 210.11(C)(2) NEC 210.12(B)

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NEC 210.23(B), Exception NEC 210.50(C) NEC 220.52(F) NEC 220.82(B)(2) NEC 220.83(A)(2) NEC 220.84(C)(2)

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

328.

What is the current draw of the exhaust fan in the Laundry Room? ________________ Answer: I = VA = 90 = 0.8 am pere E

120

329.

The following is a layout of the lighting circuit for the Laundry, Powder Room, Rear Entry Hall, and Attic. Complete the wiring diagram using colored pens or pencils to indicate conductor insulation color. The GFCI receptacle in the Powder Room is not shown in the diagram because it is connected to a separate circuit, B21

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer:

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

330.

Laundry area receptacle outlets are included in the residential load calculations at a value of ________________ volt-amperes per circuit. Choose one: 1000, 1500, 2000 volt-amperes.

Answer: 1500 volt-amperes, NEC 220.52(B).

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331.

List the various methods of connecting an electric clothes dryer. __________________ ________________________________________________________________ ______________ Answer: A four-wire branch circuit is typically installed using nonmetallicsheathed cable, Type MC cable, electrical metallic tubing (EMT), serviceentrance cable, cord, -and-plug. The branch circuit conductors must all be insulated. The equipment grounding conductor may be insulated or bare. The neutral must not be used as the equipment grounding means.

332.

a. What is the minimum power demand allowed by the Code for an electric dryer if no actual rating is available for the purpose of calculating feeder and service- entrance conductor sizing? ________________________________________________

b. What is the current draw? ________________________________________________ Answer: a. 5000 W. See NEC 220.54. b. 5000 W  240 V = 20.8 amperes 333.

What is the maximum permitted current rating of a portable appliance on a 30-ampere individual branch circuit? ______________________________________________________ Answer: 30 × 0.80 = 24 amperes. See NEC210.23(A) and (B).

334.

What provides motor overload protection for the dryer? __________________________ ________________________________________________________________ ______________ Answer: Integral motor protection 335.

a. Must the metal frame of an electric clothes dryer be grounded? ________________

b. Is it permitted to ground the metal frame of an electric clothes dryer to the neutral conductor? ______________________________________________________________ __

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______________________________________________________________ _____________ Answer: a. Yes. See NEC 250.140. b. No, if new installation. Yes, if existing installation where an equipment grounding conductor is not present in the outlet or junction box for the dryer and the four conditions of the exception are complied with. See NEC 250.140.

336.

An electric dryer is rated at 7.5 kW and 120/240 volts, 3-wire, singlephase. The terminals on the dryer and panelboard are marked 75°C. a. What is the wattage rating? ________________________________________________ b. What is the current rating? _________________________________________________

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c. What minimum size type THHN copper conductors are required? _______________ ______________________________________________________________ _____________ ______________________________________________________________ _____________ d. If EMT is used, what minimum size is required? ________________________________ Answer: a. 7500 watts b.

7500  31.3 amperes 240

c. See Table 310.16 for conductor ampacities. Recalling NEC 110.14(C)(1), we need to base the conductor ampacity on the terminals that, in the question, are marked 75°C in both the appliance and the panel. Although THHN has 90°C insulation, we must pick the ampacity from the 75°C column. The ampacity of a 10 THHN, from the 75°C column is 35 amperes. But NEC 240.4(D) tells us that the maximum overcurrent protection (OCP) for a 10 AWG conductor is 30 amperes.

The dryer load is 31.3 amperes, so the 30-ampere OCP is not large enough to carry the load. We would need to use 35- or 40-ampere OCP. Whether we install 35- or 40-ampere OCP, the conductor must have an ampacity of not less than 35 or 40 amperes, respectively. In either case, the conductor would have to be an 8 AWG THHN, which has an ampacity of 50 amperes, based on the 75°C column in Table 310.16.

The conductors of nonmetallic-sheathed cable are rated 90°C per NEC 334.112. However, the ampacity on nonmetallic-sheathed cable is based on the 60°C column of Table 310.16 per NEC 334.80. Therefore, the minimum size nonmetallic-sheathed cable is an 8 AWG, which has an ampacity of 40 amperes. d. See Table C1, Appendix C. Three 8 AWG THHN conductors are permitted in trade size 12 EMT. The EMT provides the required equipment grounding conductor.

337.

When a metal junction box is installed as part of a new cable installation to a clothes dryer or electric range, may this box be grounded to the circuit neutral conductor? (Yes) (No)

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Answer: No This is a new branch circuit.

338.

If a residential air-conditioning unit is installed in the attic:

a. Is a lighting outlet required? _______________________________________________ b. What Code section applies? ________________________________________________ c. If a lighting outlet is required, how shall it be controlled? _____________________ ______________________________________________________________ ____________ d. What Code section applies? ________________________________________________ e. Is a receptacle outlet required? _____________________________________________ f. What Code section applies? ________________________________________________ Answer: a. Yes b. NEC 210.70(A)(3) and 210.70(C) c. The lighting outlet itself may contain a switch (such as a pull-chain) or a separate wall switch. d. NEC 210.70(A)(3) and 210.70(C) e. Yes f. NEC 210.63 339.

The Code states that a means must be provided to disconnect an appliance. In the case of an electric clothes dryer, the disconnecting means can be (Select the correct statement(s).) a. a separate disconnect switch located within sight of the appliance. b. a separate disconnect switch located out of sight from the appliance. The switch is capable of being locked in the OFF position. c. a cord-and-plug-connected arrangement.

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d. a circuit breaker in a panel that is within sight of the dryer or capable of being locked in the OFF position.

Answer: a, b, c, and d are all acceptable means of providing the disconnection means. See NEC 422.30, 422.31, 422.32, 422.33, 422.34, and 422.35.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 16: BRANCH CIRCUITS FOR THE GARAGE AND OUTDOORS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the Code or plans where necessary.

340.

What branch circuits supply the garage? ______________________________________ ________________________________________________________________ ___________ Answer: B14 lighting and B23 receptacles and garage door operator. Circuits B24-26 are identified for an optional electric vehicle charging outlet.

341.

What are the branch circuit ratings? _________________________________________ Answer: 15 amperes for branch circuit 14 and 20 amperes for branch circuit 23.

The optional branch circuit for the electric vehicle charger outlet is designated 40 amperes.

342.

How many GFCI-protected receptacle outlets are connected to the garage circuit? ________________________________________________________________ ___________ Answer: Six. Five receptacles on the walls, plus one receptacle for the overhead door operator.

343. a. How many cables enter the wall switch box located next to the side garage door?

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______________________________________________________________ _____________ ______________________________________________________________ _____________ b. How many circuit conductors enter this box? ______________________________________________________________ _____________ c. How many equipment grounding conductors enter this box? ______________________________________________________________ _____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: a. Four b. Nine; 2 supply, 2 from porch light, 2 from garage lights, and 3 for 3/4-way control. c. Four 344.

Show calculations on how to select a proper size box for problem 4. What kind of box would you use? _______________________________________________________________ ________________________________________________________________ ______________ ________________________________________________________________ ______________ Answer: Circuit conductors (four cables)

9

Equipment grounding conductors (four, but count as one only)

1

Cable clamps (There is one clamp in each of the two ganged boxes. If one box is used, then only one clamp of the same type need be counted.)

1

Wiring device (two, but count as four)

4 _____

Total

15

Select 2-gang box that can hold 15 or more 14 AWG conductors. See NEC 314.16 and Table 314.16(A). For nonmetallic boxes, see Table 314.16(B). 15 × 2 = 30 cubic in. volume needed.

345.

a. How many lights are recommended for a one-car garage? __________________ For a two-car garage? __________________ For a three-car garage? ___________________

b. Where are these lights to be located? ________________________________________ ______________________________________________________________ _____________ Answer: a. Two, three, four

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

b. Along the side and toward the front of the automobile(s) 346.

From how many points in the garage of this residence are the ceiling lights controlled? ________________________________________________________________ _______________ Answer: Three

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

347.

GFCI circuit breakers are relatively expensive compared to GFCI receptacles. How would you arrange the wiring of the garage circuit B23 to make as economical an installation as possible that complies with the Code? ______________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Let students suggest other layouts and explain reasons why they feel the suggested layout should be accepted.

GFCI requirements can bring about a number of possibilities for laying out the branch circuit wiring for Circuit B14. Let students suggest other layouts and explain reasons why they feel the suggested layout should be accepted. Figure 16-1 shows one way.

Watch out for how the receptacle for the overhead door operator is connected!

NEC 210.8(A) provides the requirements for GFCI protection. One important requirement is that the GFCI protection shall be readily accessible. This means not having to resort to a ladder. Therefore, the receptacle for the overhead garage door operator would have to be fed from some other source of GFCI protection.

One way would be to install a feed-through GFCI receptacle where branch circuit B23 is brought in. From the load side of that GFCI receptacle, everything downstream will be GFCI protected. Another way would be to install a GFCI circuit breaker for branch circuit B23. Then, everything on branch circuit B23 will be GFCI protected.

It’s a matter of comparing costs (time & material), and always keeping in mind the NEC requirements for GFCI protection.

348.

The total estimated volt-ampere load of the garage lighting branch circuit B14 draws how many amperes? Show your calculations. _____________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Answer: This question refers to branch circuit B14.

I

VA 400   3.3 amperes 120 120

349.

How high from the floor are the switches and receptacles to be mounted? _____________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: 46 in. (1.15 m)

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

350.

What type of cable feeds the post light? _________________________________________ Answer: Type UF 351.

All raceways, cables, and direct burial-type conductors require a ―cover.‖ Explain the term ―cover.‖ ________________________________________________________________ __ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The term cover is found in Note 1 to Table 300.5. It is the distance as measured from the top of an underground raceway, cable, or direct burial conductor to the top surface of finish grade, concrete, blacktop, or similar surface.

352.

In the spaces provided, fill in the cover (depth) for the following residential underground installations. See NEC Table 300.5. a. Type UF. No other protection. ________________________________________ in. b. Type UF below driveway. ________________________________________ in. c. Rigid metal conduit under lawn. ________________________________________ in. d. Rigid metal conduit under driveway. ________________________________________ in. e. Electrical metallic tubing between house and detached garage. ________________________________________ in. f. UF cable under lawn. Circuit is 120 volts, 20 amperes, GFCI-protected. ________________________________________ in. g. Rigid PVC conduit approved for direct burial. No other protection. ________________________________________ in. h. Rigid PVC conduit. Circuit is 120 volts, 20 amperes, GFCI-protected. ________________________________________ in.

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i.

Rigid conduit passing over solid rock and covered by 2 in. (50 mm) of concrete extending down to rock. ________________________________________ in.

Answer: a. 24 in. (600 mm) b. 18 in. (450 mm) c. 6 in. (150 mm) d. 18 in. (450 mm) e. Electrical metallic tubing not permitted underground f. 12 in. (300 mm)

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g. 18 in. (450 mm) h. 12 in. (300 mm) i.

2 in. (50 mm)

This information is found in Table 300.5, NEC. 353.

What section of the Code prohibits embedding Type UF cable in concrete? ___________ ________________________________________________________________ _______________ Answer: NEC 340.12(8) 354.

It is, is not, (Select one choice) permitted to splice Type UF cable that is used in direct burial applications.

Answer: It is.

355.

Using the suggested cable layout of the garage lighting circuit B14, make a complete wiring diagram of this circuit, using colored pens or pencils to indicate conductor insulation colors. The receptacles in the garage are not shown in this diagram because they are connected to circuit B23.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer:

Note: Depending on location of switches, a grounded conductor may or may not be required at each switch location for luminaires. See NEC 404.2(C).

356.

When a box-cover unit is installed for an overhead door operator, a timedelay dual- element fuse ampere rating would generally be sized at __________________________ % of the unit’s nameplate current rating.

Answer: 125% 357.

When outdoor receptacles are installed where a cord will be plugged in permanently, such as in the case of decorative lighting, the cover must provide weatherproof integrity when the cord is plugged in. True or false? (Select your answer and provide the NEC reference if the statement is true.) NEC ______________________________.

Answer: True, NEC 406.9(B)(1) and (B)(2).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

358.

In order to wire a post light, a homeowner purchased some singleconductor cable that was marked as suitable for direct burial in the ground. A separate equipment grounding conductor to the post light was not carried.

Instead, the bottom of the metal post, buried 2 ft. (0.6 m) into the ground, was used as a ground for the post light. The inspector ―red tagged‖ (turned down) the installation. Who is right—the homeowner or the electrical inspector? Explain. ________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The electrical inspector is right. NEC 250.4(A)(5) states that The earth shall not be considered as an effective ground-fault current path. NEC 250.142(B) tells us that A grounded circuit conductor shall not be used for grounding noncurrent-carrying metal parts of equipment on the load side of the service disconnection means.* NEC 250.134(B) requires that an equipment grounding conductor be run with the circuit conductors.

359.

What concerns are there when installing a low-voltage lighting system?

________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: For a given wattage, low-voltage systems draw more current than for similar wattage at 120 volts. Not taking this higher current draw into consideration will probably result in the installing of conductors that are too small. Conductors on the low-voltage side of the isolating transformer that are too small will also lead to a voltage drop problem. The lamps will not emit the proper amount of light.

360.

A power outlet for an electric vehicle charging system in the garage of the dwelling used as an example in this text is (required) (optional). (Select the correct answer.)

Answer: optional. * Source NFPA 70-2020.

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Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 17: RECREATION ROOM TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the Code or plans where necessary.

361.

What is the total current draw when all six fluorescent luminaires are turned on? (Use lamp wattage because the ballast load is unknown.) ________________________________________________________________ _______________ Answer: I = VA = 1008 = 8.4 amperes E

120

Some students might say that when all six fluorescent luminaires are turned on, the 100-watt stairway luminaire will also be on. Then: I=

VA 1108 = = 9.2 amperes E 120

362.

The junction box that will be installed above the dropped ceiling near the fluorescent luminaires closest to the stairway will have __________________ (number of) 14 AWG conductors.

Answer: 3 + 2 + 4 + 2 = 11 circuit wires. Four equipment grounding conductors also enter the box for a total of 15. The question does not ask about box fill. If it did, these four equipment grounding conductor count as one conductor.

363.

Why is it important that the ―hot‖ conductors in a 3-wire branch circuit be properly connected to opposite phases in a panelboard? ___________________________________ ________________________________________________________________ _______________ Answer: If the ungrounded conductors are connected to the same phase, the load on the neutral conductor is additive with the possibility of overloading the neutral conductor.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

364.

In the diagram, Load A is rated at 10 amperes, 120 volts. Load B is rated at 5 amperes, 120 volts.

a. When connected to the 3-wire branch circuit as indicated, how much current will flow in the neutral conductor? _______________________________________________ b. If the neutral conductor should open, to what voltage would each load be subjected, assuming both loads were operating at the time the neutral conductor opened? Show all calculations.

Answer: a. The neutral carries the unbalanced load of 10  5 = 5 amperes b. Load A : R 

E 120   12 ohms I 10

Load B : R 

E 120   24 ohms I 5

With an open neutral, A and B are in series; therefore: Rt = 12 + 24 = 36 ohms It =

E 240 = = 6.66 am peres Rt 36

Therefore, Load A: E = I  R = 6.66  12 = 80 volts Load B: E = I  R = 6.66  24 = 160 volts 365.

Calculate the watts loss and voltage drop in each conductor in the following circuit. Show calculations. Obtain resistance data from Chapter 9, Table 8, of the NEC.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: See Chapter 9, Table 8, in the NEC. The conductors in Type THHN are uncoated.

1000 ft of 12 AWG solid copper wire has a resistance of 1.93 ohms.

Therefore, 50 ft would have a resistance of 0.0965 ohm.

Watts loss in each conductor: W = I2R = 15  15  0.0965 = 21.7 watts Voltage drop in each conductor: E = IR = 15  0.0965 = 1.4 volts 366.

Unless specifically designed, all recessed incandescent luminaires must be provided with factory-installed _________________________ protection (see Chapter 7).

Answer: Thermal protection. See NEC 410.115(C).

367.

Where in the NEC would you look for the installation requirements regarding flush and recessed lighting luminaires? ________________________________________________________________ _______________ Answer: Article 410, Part X 368.

What is the current draw of the recessed luminaires above the bar? _________________ ________________________________________________________________ _______________ Answer: Four luminaires at 75 watts each: 75  4 = 300 watts I=

369.

W 300 = = 2.5 amperes E 120

a. VA load for Circuit B9 is ______________________ volt-amperes.

b. VA load for Circuit B11 is ______________________ volt-amperes. c. VA load for Circuit B12 is ______________________ volt-amperes.

Answer: a. 1170 VA b. 870 VA c. 906 VA © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Note: See Chapter 7 for discussion relating to ballasts.

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370.

Complete the wiring diagram for the Recreation Room. Follow the suggested cable layout. Use colored pencils or pens to identify the various colors of the conductor insulation.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: Complete the wiring diagram for the Recreation Room. Follow the suggested cable layout. Use colored pencils or pens to identify the various colors of the conductor insulation.

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Note to instructor: This is the first chapter in Electrical Wiring Residential where a multiwire branch circuit is used.

In addition, some branch circuits are required to have AFCI protection. Some receptacles are required to be GFCI protected. Some receptacles are required to have both AFCI and GFCI protection. In this diagram both circuits, B9 and B11 are required to be AFCI protected and all receptacles on these circuits require GFCI protection.

The advent of so many different kinds of AFCIs, GFCIs, dual-function AFCI/GFCIs, 2-pole common trip AFCI/GFCIs, and other types make the decision of how to design branch circuits a bit challenging. So much depends upon what devices are available or used.

Without question, the number 1 objective is to ―Meet Code.‖ That can be accomplished in a number of ways with the above-mentioned AFCI and GFCI devices. So much depends on how the branch circuits are laid out.

The text discusses a few possibilities. This wiring diagram is based on the circuit design (cable layout) shown in the text. There are other ways to design the circuitry for the Recreation Room.

Because of the availability of AFCI and GFCI devices—or lack thereof, it might make sense to simply run 2-wire branch circuits instead of multiwire branch circuits. If that is done, install single-pole GFCI circuit breakers, single-pole AFCI circuit breakers, single-pole dual-function AFCI/GFCI circuit breakers, and/or install GFCI receptacles where required.

However, by installing all 2-wire branch circuits, you lose the advantages of multiwire circuiting, that is, less voltage drop, less watts loss, more time, more material. Fewer connections? More connections? Larger size boxes? Smaller size boxes? More confusing? Less confusing? Easier to balance the loads? More difficult to balance the loads? Multiwire branch circuits require simultaneous disconnecting means.

Have your students come up with other circuit layouts. Discuss the pluses and minuses.

Beginning students will probably have trouble understanding the many different ways a circuit can be designed. Your advanced students will have less trouble.

Here is an opportunity for an instructor to challenge students.

Ask them what brand of circuit breakers/receptacles they use.

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Have students go on-line to check out availability of the various types of GFCIs, AFCIs, and dual-function AFCI/GFCIs. Have them look for circuit breakers and receptacles.

371.

Calculate the total current draw for Circuit B9, Circuit B11, and Circuit B12. Circuit B9 _____________________, Circuit B11 _____________________, and Circuit B12 _____________________.

Answer: Branch Circuit B-9; 780 VA ÷ 120V = 9.75 A or 8 Amperes Branch Circuit B-11; 870 VA ÷ 120V = 7.25 A or 7 amperes Branch Circuit B-12; 906 VA ÷ 120V = 7.6 A or 8 Amperes 372.

a. Is a fluorescent luminaire that is marked ―Recessed Fluorescent Luminaire‖ permitted to be installed in a suspended ceiling? __________________________

b. Is a fluorescent luminaire that is marked ―Suspended Ceiling Fluorescent Luminaire‖ permitted to be installed in a recessed cavity of a ceiling? __________ ______________________________________________________________ _____________ Answer: a. Yes b. No, these luminaires require removeable panels of a suspended ceiling in order to allow the necessary access after the installation is complete.

373.

Fixture whips are typically between _________________ and _________________ ft. long and contain conductors of the proper size and temperature rating for the luminaire.

Answer: 4, 6 374.

The NEC requires GFCI protection for receptacles located within 6 ft. (1.8 m) of the outside edge of a wet bar sink. This requirement is found in NEC _________________ ________________________________________________________________ _____________ Answer: NEC 210.8(A)(8). Sinks—where receptacles are installed within 1.8 m (6 ft) from the top inside edge of the bowl of the sink.

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375.

The NEC only requires GFCI protection of receptacles in unfinished portions of base- ments. True or false? (Select the correct answer.)

Answer: False. NEC 210.12(B) states that All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas shall be protected by any of the means described in 210.12(A)(1) through (6).* 376.

Lay-in fluorescent luminaires that rest on the metal framing members of a suspended ceiling cannot just lay on the framing members. NEC 410.36(B) requires that the luminaires must _____________________________________________________________ ________________________________________________________________ _____________ ________________________________________________________________ _____________ Answer: Be securely fastened to the framing members by bolts, screws, rivets, or listed clips. This will keep the ―lay-in‖ luminaire from falling out of the ceiling in the event the ceiling framing members shift, such as would likely happen in the event of an earthquake.

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377.

List the rooms and/or areas in a newly constructed single-family residence where arc-fault circuit-interrupter (AFCI) protection is required by the NEC. ___________________________________________________________________ __________ ___________________________________________________________________ __________ Answer: NEC 210.12(B) requires AFCI protection in the following spaces: 

Kitchens, Family rooms, Dining rooms, Living rooms, Parlors, Libraries, Dens, Bedrooms, Sunrooms, Recreation rooms, Closets, Hallways, Laundry areas, Similar areas

* Source NFPA 70-2023.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 18: LIGHTING BRANCH CIRCUIT, RECEPTACLE CIRCUITS FOR W ORKSHOP TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW 378. a. What circuit supplies the workshop lighting? _______________________________ b. What circuit supplies the plug-in strip over the workbench? _________________ c. What circuit supplies the freezer receptacle? _______________________________ Answer: a. A17 b. A18 c. A13

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379.

Approximately how much trade size 1 2 EMT is used for connecting Circuit A13, Circuit A17, Circuit A18, and Circuit A20? ________________________________________ Answer: Approximately 160 ft (49 m). So much depends on how the EMT is ran.

Figure 18–1 shows ―home runs‖ for each of the branch circuits, yet those separate circuits could have been pulled into the same EMT runs that are installed for the lighting branch circuitry. It’s a matter of thinking it through and comparing time and material for different ways to ran the EMTs. You have to think about the need for derating the conductors’ ampacity when more than four current-carrying conductors are ran in the same raceway. You also have to consider the trade size of EMT needed when many conductors are installed in the EMT. 380. a. How is EMT fastened to masonry? ____________________________________________ ______________________________________________________________ ______________ b. The cut ends of rigid and electrical metallic tubing must be _____________________ to prevent the insulation on conductors from being damaged.

Answer: a. With EMT straps using plastic, or other suitable masonry anchors. b. Reamed

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381.

What type of luminaires are installed on the workshop ceiling?

________________________________________________________________ ____________ Answer: Five porcelain-type lampholders (two keyless; three pull-chain) that mount directly to the outlet boxes, plus the fluorescent luminaires above the workbench.

382.

A check of the plans indicates that two empty trade size 1 2 EMT conduits are installed between the basement and the attic. In your opinion, is this is a good idea? Briefly explain your thoughts. _______________________________________________________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: The empty conduits will provide an easy route from the basement to the attic for possible future electrical, electronic, or communication circuitry rather than having to ―fish‖ through the walls.

383.

When a freezer located in the basement is plugged into a receptacle, be sure that the receptacle is protected by a GFCI. Is this statement true or false?

Explain. ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: True. This chapter is about the Workshop in the basement. NEC 210.8(A)(5) requires all receptacles in an basement to have GFCI protection. See further explanation as stated in the answer to Question 9.

384.

A sump pump is plugged into a single receptacle outlet in the basement.

This receptacle (Select the correct answer.) a. must be GFCI-protected.

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b. is not required to be GFCI-protected.

Answer: a. be GFCI protected. NEC 210.8(A)(5) requires that all 125-volt through 250-voltreceptacles installed on single-phase circuits in basements be GFCI protected. Prior to the 2008 edition of the NEC, there were exceptions for single receptacles serving dedicated loads and for receptacles not readily accessible. These exceptions were deleted in the 2008 NEC. The only remaining exemption to the GFCI requirement in NEC 210.8(A)(5) is for a receptacle supplying a permanently installed fire alarm or burglar alarm system.

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385.

When a 120-volt receptacle outlet is provided for the laundry equipment in an unfinished basement, what is the minimum number of additional receptacle outlets required in that basement? __________________________________________________ What is the Code reference? _________________________________________________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: One, See NEC 210.52(F) and (G).

386.

Adjustment factors for conductor ampacities must always be taken into consideration when (a) ________________________ are contained in one raceway or cable. Correction factors are applied when (b) ____________________________________ Answer: a. More than three current-carrying conductors (four or more) b. Temperatures exceed 86°F (30°C) 387.

Using the following drawing, determine what current is flowing in the neutral conductor at a. ____________________________________amperes. b. ____________________________________amperes. c. ____________________________________amperes. d. ____________________________________amperes.

Answer: a. 0 amperes

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

b. 4 amperes c. 2 amperes d. 5 amperes

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388.

When a single receptacle is installed on an individual branch circuit, the receptacle must have a rating _____________________ than the rating of the branch circuit.

Answer: Not less. NEC 210.21(B)(1).

389.

Calculate the total current draw of Circuit A17 if the luminaires and the exhaust fan have the estimated loads shown and are operating.

Answer: I  VA  760  6.3 am peres E

120

Note: The chime transformer and the smoke detectors are permanently connected.

390.

A conduit body must have a cross-sectional area not less than (two) (three) (four) times the cross-sectional area of the (largest) (smallest) conduit to which it is attached. (Select the correct answers.)

Answer: Two; largest. NEC 314.16(C).

391.

A conduit body may contain splices if marked with (Select the correct answer.) a. the manufacturer’s logo. b. its in.3 area. c. the size of conduit entries.

Answer: b. its in.3 area. Its cubic inch volume. See 314.16(C)(2).

392.

What size box would you use where Circuit A17 enters the junction box on the ceiling? ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: The junction box has three EMTs connected to it. Each EMT has three 14 AWG conductors for a total of nine conductors entering the box. A 4" square box, 1 1 2 in. deep is a good choice. The chime transformer could have been attached to this junction box instead of to the outlet box where the porcelain lampholder is located.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

393.

List the proper trade size of electrical metallic tubing for the following.

Assume that the conductors have THWN insulation. See Annex C, Table C1, NEC. a. Three 14 AWG _________________________________________________________ b. Four 14 AWG ___________________________________________________________ c. Five 14 AWG ___________________________________________________________ d. Six 14 AWG ____________________________________________________________ e. Three 12 AWG __________________________________________________________ f. Four 12 AWG ___________________________________________________________ g. Five 12 AWG ___________________________________________________________ h. Six 12 AWG ____________________________________________________________ i.

Six 10 AWG ____________________________________________________________

j.

Four 8 AWG ____________________________________________________________

Answer: a. trade size 1 2 b. trade size 1 2 c. trade size 1 2 d. trade size 1 2 e. trade size 1 2 f. trade size 1 2 g. trade size 1 2 h. trade size 3 4 © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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i.

trade size 1 2

j.

trade size 3 4

394.

According to the Code, what trade size EMT is required for each of the following combinations of conductors? Show all calculations. Refer to NEC Chapter 9, Table 4, Table 5, and Table 8. a. Three 14 AWG THHN, four 12 AWG THHN ______________________________________________________________ ______________ b. Two 12 AWG THHN, three 8 AWG THHN ______________________________________________________________ ______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

c. Three 3/0 AWG THHN, two 8 AWG THHN ______________________________________________________________ ______________ Answer: a. 0.0097 0.0097 0.0097 0.0133 0.0133 0.0133 0.0133 _______ 0.0823 sq. in. Use trade size 1 2 electrical metallic tubing. Refer to NEC Chapter 9, Table 4 and Table 5. b. 0.0133 0.0133 0.0366 0.0366 0.0366 _______ 0.1364 sq. in. Use trade size 3 4 electrical metallic tubing. Refer to NEC Chapter 9, Table 4 and Table 5. c. 0.2679 0.2679 0.2679 0.0366 0.0366 _______ 0.8769 sq. in. Use trade size 2 electrical metallic tubing. Refer to NEC Chapter 9, Table 4 and Table 5.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

395.

When more than three current-carrying conductors are installed in one raceway, their ampacities must be reduced according to NEC ___________________________________ Answer: NEC 310.15(C)(1) and Table 310.15(C)(1)

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396.

a. The following is a project. We need four 15-ampere branch circuits. We will use two 3-wire multiwire branch circuits and 14 AWG THHN conductors.

We will install the conductors in EMT. The EMT will serve as the equipment grounding conductor. The room temperature will not exceed 86°F (30°C). The connected load is nonmotor and is noncontinuous.

1. What is the minimum trade size EMT? ___________________________________ 2. What is the ampacity of the conductors before derating? __________________

___________________________________________________________ ____________ 3. What is the ampacity of the conductors after derating? ____________________ ___________________________________________________________ ____________ 4. What is the maximum overcurrent protection permitted for these conductors? ___________________________________________________________ ____________ ___________________________________________________________ ____________ ___________________________________________________________ ____________ b. Let’s increase the conductor size to 12 AWG THHN for the same installation to see what happens.

1. What is the minimum trade size EMT? ___________________________________ ___________________________________________________________ ____________ 2. What is the ampacity of the conductors before derating? __________________ ___________________________________________________________ ____________

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3. What is the ampacity of the conductors after derating? ____________________ ___________________________________________________________ ____________ 4. What is the maximum overcurrent protection permitted for these conductors? ___________________________________________________________ ____________ ___________________________________________________________ ____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: a. Two 3-wire branch circuits require six conductors—four ―hots‖ and two neutrals. Because these are multiwire branch circuits, the neutral conductors need not be counted for derating purposes. Although we have six conductors, only four are considered current carrying. See NEC 310.15(E)(1), Table 310.15(C)(1) and 310.15(C)(1).

1. Table C1 in Annex C of the NEC indicates that a trade size 1 2 EMT can hold up to twelve 14 AWG-THHN conductors. Hard to believe, but that number is the result of calculating the 40% raceway fill according to Table 1, Chapter 9, of the NEC. Let’s walk through the proof. 

From Table 5, Chapter 9, of the NEC the cross-sectional area of 14 AWG-THHN is 0.0097 in.2 Then: 0.0097  12 = 0.1164 in.2 total crosssectional area.



From Table 4, Chapter 9, of the NEC, 40% fill of trade size 1 2 EMT is 0.122 in.2



Therefore, twelve 14 AWG-THHN conductors fit into a trade size 1 2 EMT.

2. From Table 310.16, the ampacity of 14 AWG-THHN conductors is 25 amperes.

3. From Table 310.15(C)(1), the derating (adjustment) factor for four to six current-carrying conductors is 80%. Therefore: 25  0.80 = 20 amperes.

4. In Table 310.16, we find an asterisk (*) after 14, 12, and 10 AWG conductors. The footnote below the table refers us to NEC 240.4(D), where we find that the maximum overcurrent device for a 14 AWG conductor is 15 amperes. Watch out when derating, correcting, and adjusting the ampacity of a conductor. The permission in NEC 240.4(B) to use the next standard size overcurrent device has tough restrictions. One key factor is whether the load is fixed or cord-and-plug connected. b. 1. Table C1 in Annex C of the NEC indicates that a trade size 1 2 EMT can hold up to nine 12 AWG-THHN conductors. Hard to believe, but that number is the result of calculating the 40% raceway fill according to Table 1, Chapter 9, of the NEC. Let’s walk through the proof. 

From Table 5, Chapter 9, of the NEC, the cross-sectional area of 12 AWG-THHN is 0.0133 in.2 Then: 0.0133  9 = 0.1197 in.2 total crosssectional area.

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

From Table 4, Chapter 9, of the NEC, 40% fill of trade size 1 2 EMT is 0.122 in.2



Therefore, nine 12 AWG-THHN conductors fit into a trade size 1 2 EMT.

2. From Table 310.16, the ampacity of 12 AWG-THHN conductors is 30 amperes.

3. From Table 310.15(C)(1), the derating (adjustment) factor for four to six conductors is 80%. Therefore: 30  0.80 = 24 amperes.

4. In Table 310.16, we find an asterisk (*) after 14, 12, and 10 AWG conductors. The footnote below the table refers us to NEC 240.4(D), where we find that the maximum overcurrent device for a 12 AWG conductor is 20 amperes.

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397.

It (is) (is not) necessary to count equipment grounding conductors, a neutral conductor that carries the unbalanced current from other conductors of the same circuit, and/or ―travelers‖ when installing 3-way and 4-way switches for the purposes of derating the ampacity of these conductors. (Select the correct answer.) Explain. ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: Is not. It is not necessary to count these conductors for derating (adjustment factor) purposes. NEC 310.15(B)(3)(a) uses the phrase currentcarrying conductors. When applying the derating factors of NEC 310.15(B)(3)(a): 

Equipment grounding and bonding conductors are not required to be counted as current-carrying, 310.15(F).



The neutral conductor that carries the unbalanced current from other conductors of the same circuit is not required to be counted, NEC, 310.15(E)(1).



In the case of ―travelers,‖ only one conductor in each pair carries current at any one time, so each pair of ―travelers‖ is counted as one current-carrying conductor.

Although the above conductors are not counted for purposes of derating (adjusting), they must be included when calculating raceway fill. The neutral conductors are part of the branch circuit and take up space.

Equipment and bonding conductors are required to be counted when calculating raceway fill, Table 1, Chapter 9, Note (3).

398.

What is the minimum number of receptacles required by the Code for each unfinished portion in basements? ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: At least one, NEC 210.52(G). This is in addition to the laundry receptacle.

399.

For laundry equipment in basements, what sort of electrical circuitry is required by the Code?

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________________________________________________________________ _______ ________________________________________________________________ _____________ ________________________________________________________________ _____________ Answer: NEC 210.11(C)(2) requires a separate branch circuit to the laundry receptacle(s). The receptacle must be within 6 ft (1.8 m) of the intended location of the washer, NEC 210.50(C). The branch circuit is not permitted to supply other loads and must be a 20-ampere branch circuit, NEC 210.11(C)(2).

400.

When raised covers are used for receptacles, does the Code permit fastening the receptacle to the cover with the one center No. 6-32 screw? Yes _______________ No _______________ NEC _______________.

Answer: No. NEC 406.5(C). A single screw is permitted if the device assembly and box cover are listed and identified for securing by a single screw.

401.

The following is a layout of the lighting circuits for the workshop. Using the wiring layout in Figure 18-1, make a complete wiring diagram. Use colored pencils or pens to indicate conductors.

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220

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Answer:

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402.

NEC 210.8(A)(5) requires that GFCI protection be provided for all receptacles in base- ments. Are there any exceptions? ________________________________________________________________ _____________ ________________________________________________________________ _____________ ________________________________________________________________ _____________ Answer: The only remaining exemption to the GFCI requirement in NEC 210.8(A)(5) is for a receptacle supplying a permanently installed fire alarm or burglar alarm system. See Question 9 for further explanation.

403.

Where loads are likely to be deemed continuous loads, the calculated load for branch circuits and feeders must be figured at (100%) (125%) (150%) of the continuous load, (plus) (minus) the noncontinuous load. This requirement generally (does) (does not) apply to residential wiring. (Select the correct answers.)

Answer: 125%; plus; does not. As mentioned in the text, water heaters through 120 gallons and fixed electric space heating branch circuits are not considered as continuous loads. Snow-melting equipment (heating cables buried in driveways) can be classified as continuous loads. The branch-circuit conductors and overcurrent protective devices to be sized at not less than 125% of the load.

See NEC 422.13, 424.3(B) and NEC 426.4. Motor branch-circuit conductors must not be less than 125% of the motor’s full load current. See NEC 430.22(A).

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 19: SPECIAL-PURPOSE OUTLETS—W ATER PUMP, W ATER HEATER TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW WATER PUMP CIRCUIT Note: Refer to the Code or the plans where necessary. © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Water Pump and Branch Circuit ▲ B 404.

Does a jet pump have any electrical moving parts below the ground level? ________ ________________________________________________________________ _____________ Answer: No, the pump remains above ground and uses a pressurized stream of water pumped into the well to start the flow of water out of the well.

405.

For a jet pump, which is larger, the drive pipe or the suction pipe? ________________ Answer: The suction pipe 406.

Where is the jet of the pump located? __________________________________________ Answer: Just above the water level 407.

What does the impeller wheel move? __________________________________________ Answer: Water 408.

Where does the water flow after leaving the impeller wheel?

a. _____________________________________________ b. _____________________________________________ Answer: a. To the storage tank b. Down the drive pipe

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409.

What prevents water from draining back into the pump from the tank? ___________ ________________________________________________________________ _____________ Answer: A check valve 410.

What prevents water from draining back into the well from the equipment? _______ ________________________________________________________________ _____________ Answer: The foot valve 411.

What is compressed in the water storage tank? _________________________________ Answer: Air 412.

Explain the difference between a 2-wire submersible pump and a 3-wire submersible pump. ________________________________________________________________ ______ ________________________________________________________________ _____________ ________________________________________________________________ _____________ ________________________________________________________________ _____________ Answer: A submersible pump that contains all of the starting components in the motor itself and does not have ―above- ground‖ starting components is referred to as ―2-wire‖ pump. A submersible pump that has ―above-ground‖ starting components is referred to as a ―3-wire‖ pump.

413.

What is a common speed for jet pump motors? _________________________________ Answer: 3400 r/min 414.

Why is a 240-volt motor preferable to a 120-volt motor for use in this residence? ________________________________________________________________ _____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

________________________________________________________________ _____________ Answer: A 240-volt motor operates using one-half the current used by a 120-volt motor. See Table 430.248. The higher voltage also means the starting current is lower resulting in lower voltage drop.

415.

How many amperes does a 1-horsepower, 240-volt, single-phase motor draw? (See Table 430.248.) _______________________________________________________________ Answer: 8 amperes. The text above Table 430.248 tells us that the current values in the table are OK for voltages 220 to 240 volts.

416.

What size are the conductors used for this branch circuit? _______________________ Answer: 12 AWG copper 417.

What is the branch-circuit overcurrent protective device? ________________________ Answer: A 20-ampere, double-pole circuit breaker in Main Panelboard A

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

418.

What provides the overload protection for the pump motor? ______________________ ________________________________________________________________ _____________ ________________________________________________________________ _____________ Answer: A double-pole thermal overload switch mounted next to the pump. For submersible pumps, the controller contains the overload protection. Back-up overload protection is accomplished by installing dual-element, time-delay fuses in the disconnect switch.

419.

What is the maximum ampere setting permitted for overload protection of the 1-horsepower, 240-volt pump motor? __________________________________________ Answer: 10 amperes (8

1.25). See NEC 430.32.

420.

Submersible water pumps operate with the electrical motor and actual pump located (Select the correct answer.) a. above permanent water level. b. below permanent water level. c. half above and half below permanent water level.

Answer: b. Below permanent water level 421.

Because the controller contains the motor starting relay and the running and starting capacitors, the motor itself contains __________________________________________ Answer: No contacts or relays that might require servicing or replacement. The only moving part is the rotor.

422.

What type of pump moves the water upward inside of the deep-well pipe? ________ ________________________________________________________________ _____________ Answer: Centrifugal pump 423.

Proper pressure of the submersible pump system is maintained by a ______________ ________________________________________________________________ _____________ © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: Pressure switch 424.

Fill in the data for a 16-ampere electric motor, single-phase, no Code letters. a. Branch-circuit short-circuit and ground-fault protection: non-time-delay fuses: Normal size ____________________ A ____________________ A Switch size ____________________ A ______________________ A

Maximum size Switch size

b. Branch-circuit short-circuit and ground-fault protection: dual-element, timedelay fuses: Normal size ____________________ A Maximum size ____________________ A Switch size ____________________ A size ______________________ A

Switch

c. Branch-circuit short-circuit and ground-fault protection: instantaneous-trip circuit breaker: Normal setting ____________________ A Maximum setting ____________________ A d. Branch-circuit short-circuit and ground-fault protection: inverse time breaker: Normal rating ____________________ A Maximum rating ____________________ A e. Branch-circuit conductor size, Type THHN ____________________ Ampacity ____________________ A f. Motor overload protection using dual-element time-delay fuses: Maximum size ____________________ A Answer: The information needed is found in NEC 430.52 and Table 430.52. a. Normal size: 16

3 = 48A (use 50A) Switch size: 60A

Maximum size: 16 b. Normal size: 16

4 = 64A (use 60A)

Switch size: 60A

1.75 = 28A (use 30A)

Switch size: 30A

Maximum size: 16 c. Normal setting: 16 Maximum setting: 16 d. Normal setting: 16

2.25 = 36A (use 35A) Switch size: 60A 8 = 128A 13 = 208A 2.5 = 36A (use 40A)

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Maximum setting: 16

4 = 64A (use 60A)

e. Use 12 AWG THHN because we must use the 60°C column in conformance to 110.14(C). 16 1.25 = 20A conductor. See NEC 430.22 and Table 310.16. f. Maximum size: 16

1.25 = 20A. See 430.32.

425.

The NEC is very specific in its requirement that submersible electric water pump motors be grounded. Where is this specific requirement found in the Code? ________________________________________________________________ _____________ ________________________________________________________________ _____________ Answer: NEC 250.112(L) 426.

Does the NEC allow submersible pump cable to be buried directly in the ground? ________________________________________________________________ _____________ ________________________________________________________________ _____________ Answer: Yes, but only if the cable is marked Type UF or Type USE.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

427.

Must the disconnect switch for a submersible pump be located next to the well? ________________________________________________________________ _____________ ________________________________________________________________ _____________ Answer: Refer to Article 430, Part IX. Here we find requirements for the disconnecting means for motors. Also see NEC 422.32. Basically, a disconnect is required within sight of the controller, 430.102(A) and within sight of the motor, 430.102(B). There is an Exception to 430.102(B) to the ―in sight‖ requirement for submersible pumps but it is not applicable to a typical aboveground water pump installation.

Obviously the disconnect cannot be in sight of the submersible pump motor, because the motor is down inside the well casing. The disconnect can be within sight of the controller. The disconnect can be in sight of the well cap (the motor location and driven machinery) where the underground supply conductors and the ―drop‖ cable conductors are spliced together. Whether a disconnect is required on the outside of the house (either on the house or at the well cap) for submersible pumps should be checked out with the local electrical inspector. The important issue here is the safety of anyone working on the pump. Assurance is needed that, when the worker turns OFF the electrical power to the pump, it remains OFF until the worker decides to turn the power back on. The disconnecting means required on the supply side of the controller must be capable of being locked in the open position.

There is no compromise to safety!

428.

A metal well casing (shall) (shall not) be bonded to the pump’s equipment grounding conductor or by grounding it with a separate equipment grounding conductor run all the way back to the same ground bus in the panelboard that supplies the pump circuit. (Select the correct answer.) Where is this NEC requirement?

Answer: Shall. NEC 250.112(M).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

WATER HEATER CIRCUIT Water Heater and Branch Circuit ▲ C 429.

According to NEC 422.47, the high-temperature limit control must disconnect ______________________ of the ungrounded conductors. The hightemperature control limits the maximum water temperature to ______________________°F (______________________°C).

Answer: All; 190°F (88°C). The 190° (88°C) temperature limit is a UL Safety Standard requirement.

430.

A major hazard involved with water heaters is that they operate under whatever pressure the serving water utility supplies. Water stays liquid at temperatures higher than the normal boiling point of 212°F (100°C). If the hightemperature limit control failed to operate for whatever reason, should a pipe burst or a faucet be opened, the pressure would instantly drop to normal atmospheric pressure, causing the superheated water to turn into _____________________ that could result in ______________________. To prevent this from happening, water heaters are equipped with pressure/temperature relief valves.

Answer: Steam; severe burns or death 431.

Magnesium rods are installed inside the water tank to reduce ______________________ Answer: Corrosion 432.

The heating elements in electric water heaters are generally classified into two categories. These are ______________________ density and ______________________ density elements.

Answer: Low; high 433.

An 80-gallon electric water heater is energized for the first time.

Approximately how many hours would it take to raise the water temperature 80°F (26.67°C) (from 40°F to 120°F [4.44°C to 48.89°C])? The water heater has a 3000-watt heating element. ________________________________________________________________ _____________ ________________________________________________________________ _____________ Answer: Refer to Table 19–1. A 3000-watt element can raise approximately 15.5 gallons per hour using the 80°F column. Therefore, 80  15.5 = 5.16 hours

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

434.

What term is used by utilities when the water heater power consumption is measured using different rates during different periods of the day? _________________________ Answer:―Time-of-use,‖ or ―time-of-day,‖ or ―off-peak‖ metering 435.

Explain how the electric utility in your area meters residential electric water heater loads. ________________________________________________________________ _____________ ________________________________________________________________ _____________ ________________________________________________________________ _____________ Answer: The text discusses many ways that electric water heating might be metered. It depends on the utility. Some methods are ―time-of-use‖ meters that can be programmed; ―time-of-use‖ using separate meters and time/clock combinations; radio controlled; one meter using a sliding rate schedule of ―so much per kWH for the first xxx kWHs, then so much per kWH for the next xxx kWHs,‖ and so on. The terms utility controlled or customer controlled can be discussed. The purpose of this question is to be sure that the students know what is happening in the area where they are living and/or working.

436.

For residential water heaters, the Consumer Product Safety Commission suggests a maximum temperature setting of ___________________°F (___________________°C). Some states have laws stating a maximum temperature setting of ___________________°F (___________________°C).

Answer: 130°F (54°C); 120°F (49°C) 437.

An 80-gallon electric water heater has 60°F (15.56°C) incoming water.

How many minutes can a 3-gallon/minute showerhead be used to draw 105°F (40.56°C) water if the water heater thermostat is set at 120°F (48.89°C)?

Answer: Approximately 25 minutes 438.

Approximately how long would it take to produce serious burns to an adult with 140°F (60°C) water? ________________________________________________________________ Answer: Approximately 5 seconds. Refer to Table 19-3.

439.

Two thermostats are generally used in an electric water heater.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

a. What is the location of each thermostat? ______________________________________ ______________________________________________________________ ______________ b. What type of thermostat is used at each location? ______________________________ ______________________________________________________________ ______________ Answer: a. Approximately 3 4 of the way up from the bottom of tank and 1 4 of the way up from the bottom of tank b. Upper—interlocking or snap-over type Lower—single-pole, on or off variety 440.

a. How many heating elements are provided in the heater in the residence discussed in this text? ______________________________________________________________

b. Are these heating elements allowed to operate at the same time? _____________ Answer: a. Two b. No

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

441.

When does the lower heating element operate? _________________________________ ________________________________________________________________ ______________ Answer: When the water in the upper part of the tank reaches 150°F (65.56°C) and the upper thermostat snaps over, allowing the lower element to operate 442.

The Code states that for water heaters having a capacity of 120 gallons (450 L) or less, the branch circuit must have a rating of not less than _______________________% of the rating of the water heater.

Answer: 125% 443.

Why does the storage tank hold the heat so long? _________________________________ Answer: The insulation is designed to minimize heat loss.

444.

The electric water heater in this residence is connected for ―limited demand‖ so that only one heating element can be on at one time a. What size wire is used to connect the water heater? ____________________________ b. What size overcurrent device is used? _________________________________________ Answer: a. 10 AWG b. 30 amperes (See Schedule of Special Purpose Outlets in the Specifications in the text and Main Service Panelboard A Directory in Chapter 27.)

445.

a. If both elements of the water heater in this residence are energized at the same time, how much current will they draw? (Assume the elements are rated at 240 volts.)

b. What size and Type THHN wire is required for the load of both elements?

Show calculations.

Answer: a. I 

W (4500  2)   37.5 amperes E 240

b. 37.5  1.25 = 46.9 amperes. See NEC 422.13 and Table 310.16.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Though an 8 AWG copper conductor with THWN or similar 75°C insulation and 75°C terminals would be required if both elements are energized at the same time, the elements of the water heater used in this residence are interlocked so only one of the two elements can be energized at the same time.

446.

a. How much power in watts would the two elements in problem 17 use if connected to 220 volts? Show calculations.

b. What is the current draw at 220 volts? Show calculations.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: a. Correct ion Fact or = Applied Volt age Squared Rat ed Volt age Squared

=

Then, 9000

220 × 220 = 0.84 240 × 240

0.84 = 7560 watts

b. I = W = 7560 = or 34.4 amperes E

220

447.

A condominium owner complains of not getting enough hot water. The service technician checks the voltage at the water heater and finds the voltage to be 208 volts. The technician checks further and finds the electrical service on the building to be a 120/208-volt, three-phase, 4-wire system. The main electrical panelboard for each condominium unit is fed with a 3-wire supply. The nameplate on the electric water heater is marked 4500 watts, 240 volts. What is the wattage output of the heating element in this water heater when connected to a 208-volt supply? ________________ Answer: This electric water heater is rated 4500 watts at 240 volts. When connected to 208 volts, the current draw and wattage output are reduced. There are many ways to calculate the current and wattage at the reduced voltage. Here are two.

Method 1: Correct ion Fact or =

Therefore, 4500

Applied Volt age Squared 208 × 208 43,264 = = = 0.75 (75%) Rat ed Volt age Squared 240 × 240 57,600

0.75 = 3375 watts

Method 2: Calculations at rated voltage: E2 240 × 240 = = 12.8 ohm s W 4500 E 240 I= = = 18.75 am peres R 12.8

R=

W = I2R = 18.75

18.75

12.8 = 4500 watts

Calculations at 208 volts: Assume that the resistance is 12.8 ohms.

W=

E2 208 × 208 43,264 = = = 3380 w at t s R 4500 12.8

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

I=

W 3380 = = 16.25 amperes E 208

W = I2R = 16.25

16.25

12.8 = 3380 watts

Note: There will be slight differences in answers, depending on how many places behind the decimal point are used. Electricians obtain satisfactory results working with one or two places behind the decimal point.

448.

For a single, non-motor operated electrical appliance rated greater than 13.3 amperes that has no marking that would indicate the size of branch-circuit overcurrent device, what percentage of the nameplate rating is used to determine the maximum size branch-circuit overcurrent device? ______________________________________________ Answer: 150% or next standard higher rating if there is no standard ampere rating based on the 150% calculation. See NEC 422.11(E).

449.

A 7000-watt, resistance-type heating appliance is rated 240 volts. What is the maximum size fuse permitted to protect the branch-circuit supplying this appliance? ________________________________________________________________ ______________ Answer: I = W = 7000 = 29.167 amperes E

240

The minimum branch rating is 29.67  1.25 = 36.46 amperes (use a 40-ampere OCD).

The minimum conductor ampacity is 29.67  1.25 = 36.46 amperes (round up to 40 amperes). Checking NEC Table 310.16, we find in the 60°C column that an 8 AWG conductor has an ampacity of 40 amperes. It is also properly protected by the 40-ampere OCD. According to NEC 422.11(E), the maximum overcurrent protection is 29.67  1.5 = 43.75 amperes or next standard size as found in NEC 240.6(A), which is a 45ampere OCD. If we chose to use a 45-ampere OCD, then an 8 AWG with an ampacity of 40 amperes would not be properly protected. We would have to increase the wire size to 6 AWG having an ampacity of 55 amperes. If all terminals and the conductor insulation are rated 75°C, the 8 AWG conductor would be acceptable with an ampacity of 50 amperes.

From this discussion, it can readily be seen that the need to use the 150% multiplier as permitted in NEC 422.11(E) is for those rare instances in which there is a mismatch between a conductor ampacity and an OCD ampere rating. © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

For this 7000-watt, 240-volt load, a 40-ampere OCD and 40-ampere 8 AWG conductors would be the best choice.

450.

The Code requirements for standard resistance electric water heaters are found in Article 422 of the Code. Because heat pump water heaters contain a hermetic refrigerant motor compressor, the Code requirements are found in Article ____________________ of the Code.

Answer: Article 440

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

451.

In your area, is the branch-circuit breaker or switch for the electric water heater branch circuit acceptable as the disconnecting means, or are you required to install a separate disconnect within sight of the water heater? Provide a brief explanation. ________________________________________________________________ ______________ Answer: The answer to this question will vary in different parts of the country, depending on how the electrical inspector interprets the NEC.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 20: SPECIAL-PURPOSE OUTLETS FOR RANGES, COUNTER -MOUNTED COOKING UNIT , AND W ALL-MOUNTED OVEN TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW COUNTER-MOUNTED COOKING UNIT CIRCUIT Note: Refer to the Code or the plans where necessary.

Counter-Mounted Cooking Unit Branch Circuit ▲ G 452.

a. What branch circuit supplies the counter-mounted cooking unit in this residence?

______________________________________________________________ ______________ b. What is the rating of this branch circuit? ______________________________________ Answer: a. Circuit B2-4 b. 40 amperes 453.

What three methods may be used to connect counter-mounted cooking units?

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: What three methods may be used to connect counter-mounted cooking units? a. By running the supply cable to a junction box attached to the appliance b. By running the supply cable to a junction box attached to a length of flexible conduit furnished by the appliance manufacturer c. By running the supply cable to a range receptacle of adequate capacity, then attaching a cord set to the appliance

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

454.

Is it permissible to use standard 60°C insulated conductors to connect all counter- mounted cooking units? ______________________________________________________ Why? ___________________________________________________________________ ____ Answer: Not necessarily. Check for a label on the appliance that will indicate if there is a requirement for a conductor insulation suitable for higher temperatures.

The conductors in nonmetallic-sheathed cable are rated for 90ºC. 455.

What is the maximum operating temperature (in degrees Celsius) for a

a. conductor with Type TW insulation? _______________________________________ b. conductor with Type THW insulation? _______________________________________ c. conductor with Type THHN insulation? _______________________________________ Answer: a. 60ºC b. b. 75ºC c. 90ºC See Table 310.4(1).

456.

The NEC permits the following wiring methods to supply household built-in ovens and ranges. True or false? (Select the correct answer.) a. Nonmetallic-sheathed cable

(True) (False)

b. Armored cable Type AC or Type MC (True) (False) c. Flexible metal conduit

(True) (False)

Answer: a.

True

b.

True

c.

True

457.

For electric ranges that have a calculated demand of 8 3 4 kW or more, the neutral conductor can be reduced to _______________________% of the

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

branch-circuit rating but shall not be smaller than _______________________ AWG. Answer: 70%; not be smaller than 10 AWG 458.

One kilowatt equals _______________________ Btu per hour.

Answer: 3412

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459.

Older style electric ranges had heat control knobs that had ―indents‖ that could be felt when rotating the knob to adjust temperature to three, five, or seven different heat positions. Most new electric ranges have control knobs that do not have ―indents.‖ This type of heat control is known as a(n) ______________________ heat control.

Answer: Infinite 460.

When an individual branch circuit supplies a counter-mounted cooking unit, what Code reference tells us not to apply the demand factors of Table 220.55 and requires us to calculate the load based on the appliance’s actual nameplate rating? ________________________________________________________________ _______________ Answer: Note 4 to Table 220.55 WALL-MOUNTED OVEN CIRCUIT AND FREE-STANDING RANGE Wall-Mounted Oven Circuit ▲ F and Free-Standing Range 461.

To what branch circuit is the wall-mounted oven connected? ______________________ Answer: Circuit B6-8 462.

An oven is rated at 7.5 kW. This is equal to

a. ______________________ watts. b. ______________________ amperes at 240 volts.

Answer: a. 7500 watts b 7500 watts

b. I 

W 7500   31.3 amperes E 240

463. a. What section of the Code governs the grounding of a wall-mounted oven? ________ ______________________________________________________________ ______________ b. By what methods are wall-mounted ovens permitted to be grounded?

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

______________________________________________________________ ______________ ______________________________________________________________ ______________ Answer: a. NEC 250.112 for permanently connected and NEC 250.114 for cord-andplug- connected b. By any of the methods listed in NEC 250.118. For most residential wiring, the equipment grounding conductor in nonmetallic-sheathed cable, the combination metal armor and bonding wire of armored cable, or a metallic raceway provides the equipment grounding means for the frame of the appliance. On installations existing before the adoption of the 1996 NEC only, grounding the frames of electric ranges and dryers to the circuit’s neutral conductor is acceptable. See NEC 250.140.

464.

What is the type and ampere rating of the overcurrent device protecting the wall- mounted oven in this residence? Hint: Refer to the Schedule of Special-Purpose Outlets in the Specifications. ____________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Two-pole, 30-ampere, 240-volt circuit breaker 465.

Approximately how many ft. (m) of cable are required to connect the oven in the residence? ________________________________________________________________ ____ ________________________________________________________________ _______________ Answer: 20 ft (6.0 m) 466.

When connecting a wall-mounted oven and a counter-mounted cooking unit to one branch circuit, how long are the taps to the individual appliances permitted to be? ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: The Code does not specify a length for the taps. NEC 210.19(A)(3), Exception No. 1, states that taps must be no longer than necessary to service the appliance. The flexible metal conduit provided by manufacturers of built-in electrical ovens and cooktops are not less than 3 ft (900 mm) and no longer than 6 ft (1.8 m).

467.

The branch-circuit load for a single wall-mounted self-cleaning oven or counter- mounted cooking unit must be the ____________________ rating of the appliance.

Answer: Nameplate. Table 220.55 Note 4.

468.

A 6 kW counter-mounted cooking unit and a 4 kW wall-mounted oven are to be installed in a residence. Calculate the maximum demand according to Column C of Table 220.55. Show all calculations. Both appliances will be connected to the same branch circuit. ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The connected load is 6 kW + 4 kW. Note 4 to Table 220.55 states that the nameplate rating of these two appliances may be added together, then treat the total kW as if it were a single range. In Column C of Table 220.55, the maximum demand is 8 kW. 469.

The size of the neutral conductor supplying an electric range is permitted to be based on ________________________% of the branch-circuit rating.

Answer: 70%. See NEC 210.19(A)(3), Exception No. 2, and NEC 220.61(B).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

470.

A free-standing electric range is rated 11.8 kW, 120/240 volts. The wiring method is nonmetallic-sheathed cable. Use the 60°C column of Table 310.16 in conformance to 110.14(C). Answer the following questions: a.

According to Column C, Table 220.55, what is the maximum demand? ____________ kW

b.

What is the minimum size for the ungrounded copper conductors? ____________ AWG

c.

What is the minimum size neutral copper conductor? ____________ AWG

d.

What is the correct rating for the branch-circuit overcurrent protection? ____________ amperes

Answer: a. 8 kW. See Column C, Table 220.55. b. 8 AWG NEC 210.19(A)(3) states that the branch-circuit conductors for household ranges and cooking appliances must have an ampacity not less than the rating of the branch circuit, and not less than the maximum load to be served.

This section also tells us that for ranges of 8 3 4 kW or more, the minimum branch-circuit rating is 40 amperes.

Using the demand permitted in Column C, Table 220.55: I

W 8000   33.3 amperes E 240

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245

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

From Table 310.16, we find that an 8 AWG conductor in the 60°C column has an ampacity of 40 amperes. This is also in compliance with NEC 210.19(A)(3). c. The neutral conductor of a 3-wire nonmetallic-sheathed cable is the same size as the phase conductors. For this question, the NMC would contain three 8 AWG conductors and one 10 AWG equipment grounding conductor.

If the wiring is a raceway method, then a smaller neutral is possible.

NEC 210.19(A)(3), Exception No. 2, permits the neutral to be sized at not less than 70% of the branch-circuit rating when: 

The range is 8 3 4 kW or more, and



The maximum demand has been computed according to Column C of Table 220.55.

Therefore, 40 × 0.70 = 28 amperes, which is a 10 AWG conductor according to Table 310.15(B)(16). d. 40 amperes NEC 210.20 requires that branch-circuit conductors and equipment be protected by overcurrent devices having a rating or setting: 

Not exceeding that specified in NEC 240.4 for conductors, and



Not exceeding that specified in the applicable article referenced in NEC 240.3.

Table 240.2 lists specific equipment. The list includes appliances. Appliances are to be protected in accordance with Article 422. NEC 422.10(A) states that Branch-circuits for household cooking appliances shall be permitted to be in accordance with Table 220.55.* NEC 240.4 states that conductors must be protected in accordance with their ampacity.

NEC 422.11(A) states that branch circuits must be protected in accordance with NEC 240.4. This section goes on to tell us that if the OCPD is marked on the appliance, the branch-circuit OCPD shall not exceed the marked rating.

Because we have determined that an 8 AWG conductor rated 40 amperes is the minimum size for the ungrounded conductors, the OCPD is 40 amperes.

So, this is a perfect match: 40-ampere conductors and 40-ampere OCPD. Recognizing that a perfect match is not always possible, NEC 422.11(E) permits the OCPD for non–motor-operated appliances rated more than 13.3 amperes (that are not marked with the required OCPD) to be sized not over

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

150% of the appliances’ rated current. NEC 422.11(E)(3) allows the use of the next higher standard size OCPD. If the appliance is marked with the maximum OCPD, then use the marked rating.

471.

A double-oven electric range is rated at 18 kW, 120/240 volts. Calculate the maximum demand according to Table 220.55. Show all calculations. ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: 18 kW exceeds 12 kW by 6 kW. See Note 1, Table 220.55.

6 × 5% = 30% increase above Table 220.55 Column C 8 kW × 0.30 = 2.4 increase. Thus, 8 + 2.4 = 10.4 kW. 472.

For the range discussed in problem 11:

a. What size 60°C ungrounded conductors are required? __________________________ b. What size 60°C neutral conductor is required? __________________________ c. What size 75°C ungrounded conductors are required? The terminal block and lugs on the range, the branch-circuit breaker, and the panelboard are marked as suitable for 75°C wire. __________________________ d. What size 75°C neutral conductor is required? Terminations are the same as in part (c). __________________________ Answer: Amperes = Wat t s = 10,400 = 43.3 amperes Volt s

240

a. An 8 AWG copper conductor has an ampacity in Table 310.16 of 40 amperes and is too small for the calculated load of 43.3 amperes. A 6 AWG copper conductor has an ampacity of 55 amperes, Table 310.16, 60°C column and is large enough. b. 43 × 0.70 = 30 amperes

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

A 10 AWG conductor has an ampacity of 30 amperes, Table 310.16, 60°C column. c. An 8 AWG conductor has an ampacity of 50 amperes, Table 310.16, 75°C column. d. 43 × 0.70 = 30 amperes A 10 AWG conductor has an ampacity of 35 amperes, Table 310.16, 75°C column.

Caution: Be very careful in selecting conductors for ampacities as found in the 75°C and 90°C columns of NEC Table 310.16. According to NEC 110.14(C)(1)(a)(1), the 60°C column of NEC Table 310.16 must be used for ampacities of 100 amperes or less, unless the equipment is marked otherwise. The conductors are only as good as the weakest link of the circuit.

473.

For ranges of 8 3 4 kW or higher rating, the minimum branch-circuit rating is _________________________ amperes.

Answer: 40 amperes, NEC 210.19(A)(3) 474.

A nonmetallic-sheathed cable is used to connect a wall-mounted oven.

The insulated conductors are 10 AWG. What is the size of the equipment grounding conductor in this cable? _________________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 20: Special-Purpose Outlets for Ranges, Counter-Mounted Cooking Unit , and Wall-Mounted Oven

Answer: 10 AWG. The answer to this question is not found in the NEC. It is found in the UL Standard 719, the Standard for nonmetallic-sheathed cable.

SIZE OF CIRCUIT CONDUCTORS (AWG) 14

SIZE OF EQUIPMENT GROUNDING CONDUCTOR IN CABLES WITH 2, 3, OR 4 CIRCUIT CONDUCTORS 14

12

12

10, 8, 6

10

4

8

3, 2

8

NEC Table 250.122 shows the minimum size of an equipment grounding conductor based upon the rating of the overcurrent device protecting the circuit conductors.

475.

Match the following statements with the correct letter. Some letters may be used more than once. ______ A 30-ampere, 3-wire receptacle

a. for the equipment grounding conductor

______ A 50-ampere, 4-wire receptacle

b. for the white neutral conductor

______ The L-shaped blade on a 30-ampere plug cap ______ The horseshoe-shaped slot on a 50-ampere receptacle

c. for the ―hot‖ ungrounded conductors d. NEMA 10-30R e. NEMA 14-50R f. NEMA 14-50P

______ A 50-ampere, 4-wire plug cap ______ Terminals X and Y ______ Terminal W ______ Terminal G

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249

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

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250

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Answer: Match the following statements with the correct letter. Some letters may be used more than once. __d__ A 30-ampere, 3-wire receptacle a.

for the equipment grounding conductor

__e__ A 50-ampere, 4-wire receptacle b.

for the white neutral conductor

__b__ The L-shaped blade on a 30-ampere plug cap

for the ―hot‖ ungrounded conductors

c.

__a__ The horseshoe-shaped slot on a d.

50-ampere receptacle

NEMA 10-30R

__f__

A 50-ampere, 4-wire plug cap

e.

NEMA 14-50R

__c__

Terminals X and Y

f.

NEMA 14-50P

__b__ Terminal W

__a__ Terminal G

476.

When connecting an appliance that is made to foreign standards, it is (select the best answer): a. important to verify the terminals to be used for the supply conductors to be certain the connections are proper. b. likely that color coding of conductor insulation colors is universal so no concern for color-coding is needed.

Answer: a

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

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252

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

477.

A receptacle is mounted inside of a kitchen cabinet for the purpose of plugging in a microwave oven. (Select the correct answer.) a. The receptacle is permitted to be connected to the same circuit that supplies the other receptacles that serve the countertop areas. b. The receptacle is not permitted to be connected to the same circuit that supplies the other receptacles that serve the countertop areas.

Answer: b The receptacle shall not be connected to the same circuit that supplies the other receptacles that serve the countertop areas. NEC 210.52, 210.52(B)(2), 210.52(C)(5)

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 21: SPECIAL-PURPOSE OUTLETS—FOOD W ASTE DISPOSER, DISHWASHER TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW FOOD WASTE DISPOSER BRANCH CIRCUIT Note:

Refer to the Code or plans where necessary.

Food Waste Disposer Branch Circuit ▲ G 478.

How many amperes does the food waste disposer draw? __________________________ Answer: 7.2 amperes 479.

a. To what branch circuit is the food waste disposer connected?

______________________________________________________________ ______________ b. What size wire is used to connect the food waste disposer? ______________________________________________________________ ______________ Answer: © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

a. B19 b. 12 AWG THHN 480.

Means must be provided to disconnect the food waste disposer. The homeowner need not be involved in electrical connections when servicing the disposer if the disconnecting means is __________________________________________________________ Answer: A 3-wire cord with a 3-wire attachment plug cap 481.

How is motor overload protection provided in most food waste disposer units? ________________________________________________________________ _______________ Answer: By a built-in thermal protector

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

482.

When running overcurrent protection is not provided by the manufacturer or if additional backup overcurrent protection is wanted, dual-element, time-delay fuses may be installed in a separate box-cover unit. These fuses are sized at not over _________________% of the full-load current rating of the motor.

Answer: 125%. See NEC 430.32(D).

483.

Why are flow switches sometimes installed on food waste disposers? ______________ ________________________________________________________________ _______________ Answer: To ensure that enough cold water flows when the food waste disposer is used 484.

Where in the NEC would you look for basic Code rules relating to grounding appliances? ________________________________________________________________ _______________ Answer: Article 250, Part VI and Part VII. In Part VI, you will find lists of items that are required to be grounded, as well as the types of acceptable means for accomplishing equipment grounding.

Refer to Article 250, Part VII, for the various methods of equipment grounding.

485.

Do the plans show a wall switch for controlling the food waste disposer?

________________________________________________________________ _______________ Answer: Yes 486.

A separate branch circuit supplies the food waste disposer in this residence.

Approximately how many ft. (m) of cable is permitted for the cord that connects the disposer? ________________________________________________________________ _______________ Answer: 12 ft (3.7 m). It is a very short distance from under the sink to panelboard B. 487.

If a receptacle is installed underneath the sink for the purpose of plugging in a cord-connected food waste disposer, must the receptacle be GFCI-protected? © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

________________________________________________________________ _______________ Answer: Yes, the receptacle is located within the kitchen. See NEC 210.8(A)(6).

488.

Is it required that the branch circuit for the waste disposer have AFCI protection? (Yes) (No) (Select the correct answer.)

Answer: Yes. Devices and outlets in the dwelling kitchen are required to have AFCI protection. The disposal is controlled by a device and the point of connection to the branch circuit constitutes an ―outlet‖ as defined in NEC Article 100.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

DISHWASHER CIRCUIT Dishwasher Branch Circuit ▲ I 489.

a. To what branch circuit is the dishwasher in this residence connected? ___________

b. What size wire is used to connect the dishwasher? _____________________________ c. Is it required that the branch circuit for the dishwasher have AFCI protection? (Yes) (No) (Select the correct answer.) ______________________________________________________________ ______________ Answer: a. B5 b. 12 AWG THHN c. Yes. 210.12(B) 490.

The dishwasher in this residence is rated (Select the correct answer.)

a. 5 A. b. 9.2 A. c. 15 A. Answer: b. 9.2 amperes 491.

The heating element is rated at (Select the correct answer.)

a. 875 watts. ______________________________________________________________ _ b. 1000 watts. ______________________________________________________________ _ c. 1250 watts. ______________________________________________________________ _ Answer:

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

a. 875 watts 492.

How many amperes at 120 volts do the following heating elements draw?

a. 750 watts ______________________________________________________________ _ b. 1000 watts ______________________________________________________________ _ c. 1250 watts ______________________________________________________________ _ Answer: a. 6.3 amperes b. 8.3 amperes c. 10.4 amperes 493.

How is the dishwasher in this residence grounded? _______________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Through the metal cable armor or contained equipment grounding conductor. (If nonmetallic-sheathed cable is used, the dishwasher is grounded with the separate equipment grounding conductor within the cable.)

494.

What type of cord is used on most portable dishwashers? __________________________ Answer: 3-wire cord 495.

How is a portable dishwasher grounded? __________________________________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: By the equipment grounding conductor in the cord supplying the dishwasher 496.

Who is to furnish the dishwasher?

________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The owner. See the specifications.

497.

What article of the Code specifically addresses electrical appliances?

________________________________________________________________ _______________ Answer: Article 422

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 22: SPECIAL-PURPOSE OUTLETS FOR THE BATHROOM CEILING HEAT/VENT/LIGHTS, THE ATTIC FAN, AND THE HYDROMASSAGE TUB TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW BATHROOM CEILING HEATER CIRCUITS Bathroom Ceiling Heater Circuits ▲ K ▲ J 498.

What is the wattage rating of the heat/vent/light? ________________________________ Answer: 1500 watts © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

499.

To what circuits are the heat/vent/lights connected? ______________________________ Answer: A12 500.

Why is a 4 in. square, 2 18 in. deep box with a 2-gang raised plaster ring or similar deep box used for the switch assembly for the heat/vent/light? _________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: To provide room for the switch assembly and all necessary splices.

Other types of boxes may be used if a 2-gang opening and sufficient room are provided.

A 4 1116 -in. square box may be used.

501. a. How many wires are required to connect the wall switches and the heat/vent/ light? ______________________________________________________________ ______________ b. What size wires are used?

Answer: a. Five b. 12 AWG 502.

Can the heating element be energized when the fan is not operating? ________________ ________________________________________________________________ ________________ Answer: No 503.

Can the fan be turned on without the heating element? ____________________________ ________________________________________________________________ ________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Answer: Yes 504.

What device can be used to provide automatic control of the heating element and the fan of the heat/vent/light? _______________________________________________________ Answer: Thermostat 505.

Where does the air enter the heat/vent/light? _____________________________________ Answer: Through the outer grille 506.

Where does the air leave this unit? _______________________________________________ Answer: Through the center grille 507.

Who is to furnish the heat/vent/light? ____________________________________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: The electrical contractor. See the Specifications.

508.

For a ceiling heater rated 1200 watts at 120 volts, what is the current draw? _________ ________________________________________________________________ ________________ Answer: I = W = 1200 = 10 amperes E

120

509.

An electrician wired up a heat/vent/light as described in this chapter. The wiring diagram showed that the electrician needed to run five conductors between the switches and the heat/vent/light. The electrician used one 12-3 nonmetallic-sheathed cable and one 12-2 nonmetallic-sheathed cable. Both cables had equipment grounding conductors. During the rough-in inspection, the electrical inspector cited ―Noncompliance with NEC 300.3(B).‖ What was the problem? _______________________ ________________________________________________________________ ________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: NEC 300.3(B) states that All conductors of the same circuit and where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cable bus assembly, trench, cable, or cord, unless otherwise permitted in accordance with NEC 300.3(B)(1) through (B)(4). * To conform to NEC 300.3(B), the best way to connect the heat/vent/light is as discussed in the text, that is, to use flexible metal conduit, EMT or ENT. ATTIC EXHAUST FAN CIRCUIT Attic Exhaust Fan Branch Circuit ▲ L 510.

What is the purpose of the attic exhaust fan? _____________________________________ ________________________________________________________________ ________________ Answer: To remove excess moisture from the dwelling. The fan can also cool the dwelling if it is decided not to run the air conditioner. This type of fan is also called a ventilator fan because it draws in outside air and exhausts the air through the louvers in the attic.

511.

At what voltage does the fan operate? ____________________________________________ Answer: 120 volts (115 volts) 512.

What is the horsepower rating of the fan motor? __________________________________ Answer: 1 4 hp 513.

Is the fan direct- or belt-driven? _________________________________________________ Answer: Direct-driven 514.

How is the fan controlled? ______________________________________________________ Answer: By an ON–OFF timer switch in the hallway between the bedrooms © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

515.

What is the rating of the dual-element, time-delay fuse in the switch/fuse box-cover unit? ________________________________________________________________ __________ Answer: 8 amperes 516.

What is the rating of the running overcurrent protection if the motor is rated at 10 amperes? ________________________________________________________________ ______ Answer: 10 × 1.25 = 12.5 amperes, which would round up to the next higher standard size of 15 amperes.

517.

What is the basic difference between a thermostat and a humidistat? _______________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: A thermostat is a temperature-sensitive device with a switching mechanism that operates with a bimetallic element. A humidistat is sensitive to humidity and contains a human hair or nylon element to operate the switching mechanism.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

518.

What size conductors are to be used for this circuit? _______________________________ ________________________________________________________________ ________________ Answer: 14 AWG 519.

How many ft. (m) of cable are required to complete the wiring for the attic exhaust fan circuit? ________________________________________________________________ _______ Answer: Approximately 50 ft (15 m) 520.

Can the metal frame of the fan be grounded to the grounded circuit conductor? _____ ________________________________________________________________ ________________ Answer: No 521.

Which section of the Code prohibits grounding equipment to a grounded circuit conductor? ________________________________________________________________ _____ Answer: NEC 250.24(A)(5) and NEC 250.142(B).

HYDROMASSAGE BATHTUB CIRCUIT Hydromassage Bathtub Branch Circuit ▲ A 522.

Which circuit supplies the hydromassage bathtub? _________________________________ Answer: A9 523.

Which of the following statements ―Meets Code‖? (Select the correct answer.) a. Hydromassage tubs and all of their electrical components shall be GFCIprotected. b. Hydromassage tubs and all of their electrical components shall not be GFCI-protected.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Answer: a. Hydromassage tubs and all of their electrical components shall be GFCI protected.

524.

Which conductor size feeds the hydromassage tub in this residence? ________________ ________________________________________________________________ ________________ Answer: 14 THHN 525.

What is the fundamental difference between a hydromassage bathtub and a spa? ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: Hydromassage bathtub: fill-use-drain Spa: fill-use-do not drain after each use

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526.

Which sections of the Code reference hydromassage bathtubs? _____________________ ________________________________________________________________ ________________ Answer: Article 680, Part VII. 527.

Must the metal parts of the pump and power panel of the hydromassage tub be grounded? ________________________________________________________________ _____ ________________________________________________________________ ________________ ________________________________________________________________ ________________ ________________________________________________________________ ________________ Answer: Yes. The manufacturer provides a green equipment grounding conductor to facilitate proper grounding. The separate circuit cable contains a bare equipment grounding conductor that is to be properly connected to the green grounding conductor from the hydromassage tub.

528.

Is it permissible to connect the hydromassage tub’s green equipment grounding conductor to the branch circuit’s grounded (white) conductor? ________________________________________________________________ ________________ Answer: No. NEC 250.24(A)(5) and NEC 250.142(B).

529.

All 125-volt, single-phase receptacles within (6 ft. [1.8 m]) (10 ft.

[3.0 m]) (15 ft. [4.5 m]) of a hydromassage tub must be GFCI-protected. (Select the correct answer.)

Answer: 6 ft (1.8 m). NEC 680.71.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 23: SPECIAL-PURPOSE OUTLETS—E LECTRIC HEATING, AIR CONDITIONING

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TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW ELECTRIC HEAT Note: Refer to the Code or plans where necessary.

Electric Heat 530. a. What is the allowance in watts made for electric heat in this residence? _________ b. What is the value in amperes of this load? ____________________________________ ______________________________________________________________ _____________ Answer: a. 13,000 watts b. I = W = 13,000 = 54.2 amperes E

240

531.

What are some of the advantages of electric heating? _____________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Electric heating is safer than a fuel combustion system; it is clean; it has the capability for individual room control; it is quiet in operation; it requires minimum maintenance.

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532.

List the different types of electric heating system installations. _____________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Heating cable (both secured to the ceiling and floor cables) unit heaters, boilers, electric furnaces, duct heaters, baseboard heaters, heat pumps, and radiant heating panels.

533.

What are the two basic voltage classifications for thermostats. ____________________ ________________________________________________________________ _______________ Answer: Line voltage and low-voltage thermostats 534.

What device is required when the total connected load exceeds the maximum rating of a thermostat? ________________________________________________________________ _ ________________________________________________________________ _______________ Answer: Relay of adequate capacity 535.

The electric heat in this residence is provided by what type of equipment? __________ ________________________________________________________________ _______________ Answer: An electric furnace 536.

At what voltage does the electric furnace operate? ________________________________ Answer: 240 volts 537.

A certain type of control connects electric heating units to a 120- or 240volt supply, depending on the amount of the temperature drop in a room. These controls are sup- plied from a 120/240-volt, 3-wire, single-phase source.

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Assuming that this type of device controls a 240-volt, 2000-watt heating unit, what is the wattage produced when the control supplies 120 volts to the heating unit?

Show all calculations. ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: 500 watts. When the voltage is reduced to one-half of its original value, the wattage is reduced to one-fourth of its original value.

First, calculate the resistance of the heating element: R = E2/W = 240 × 240 ÷ 2000 = 28.8 ohms Next, calculate the wattage at 120 volts: W = E2/R = 120 × 120 ÷ 28.8 = 500 watts

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

538.

What advantages does a 240-volt heating unit have over a 120-volt heating unit? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: For the same wattage rating, the current draw at 240 volts is one-half of the current draw at 120 volts. This can result in the use of smaller conductors, smaller raceways, less voltage drop (IR), and less watts loss (I2R) in the conductors.

539.

The white wire of a cable may be used to connect to a ―hot‖ ungrounded circuit conductor only if _______________________________________________________________ ________________________________________________________________ _______________ Answer: The conductor having white insulation is permanently reidentified. See NEC 200.6 and NEC 200.7. Note that this marking is only permitted with a cable wiring method.

540.

When not connected to the heater’s branch circuit, receptacle outlets furnished as part of a permanently installed electric baseboard heater (may) (may not) be counted as the required receptacle outlet for the space occupied by the baseboard heater. Electric baseboard heaters (shall) (shall not) be installed beneath wall receptacle outlets unless the instructions furnished with the heaters indicate that it is acceptable to install the heater below a receptacle outlet.

(Select the correct answers.)

Answer: May; shall not 541.

The branch-circuit conductors supplying a fixed electric space heater must be sized to at least _________________% of the heater’s rating according to NEC ________________.

Answer: 125%; 424.3(B) 542.

Calculate the current draw of the following electric furnaces. The furnaces are all rated 240 volts. a. 7.5 kW _____________ amperes b.

15 kW _____________ amperes c.

20 kW _____________ amperes © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Answer: a. 7.5 × 1000 = 31.25 amperes 240

b. 15 × 1000 = 62.5 amperes 240

c. 20 × 1000 = 83.3 amperes 240

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

543.

For ballpark calculations, the wattage output of a 240-volt electric furnace connected to a 208-volt supply will be approximately 75% of the wattage output of the same furnace connected to a 240-volt supply. In problem 13, calculate the wattage output of (a), (b), and (c) if connected to 208 volts. ________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: a. 7.5 × 0.75 = 5.625 kW b. 15 × 0.75 = 11.25 kW c. 20 × 0.75 = 15.00 kW 544.

A central electric furnace heating system is installed in a home. The circuit supplying this furnace (Select the most correct answer.) a. is limited to a branch circuit rated not greater than 60 amperes. b. is limited to not more than one branch circuit. c. is considered to be a continuous load.

Answer: b.

545.

What section of the Code provides the correct answer to problem 15? _______________ Answer: NEC 424.4 546.

Electric heating cable embedded in plaster, or sandwiched between layers of dry wall, creates heat. Therefore, any nonmetallic-sheathed cable run above these ceilings and buried in insulation must have its current-carrying capacity derated according to the (40°C) (50°C) (60°C) correction factors found in Table 310.15(B)(1) in the NEC. (Select the correct answer.) ____________________________________________________________ Answer: 50°C. See NEC 424.36.

547.

Wall-mounted heaters are available in _____________-volt and _____________-volt ratings.

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Answer: 120, 240 548.

Wall-mounted heaters should be located to avoid conflict with _____________________ Answer: furniture layout

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

AIR CONDITIONING Air Conditioning 549.

a. When calculating air-conditioner load requirements and electric heating load requirements, is it necessary to add the two loads together to determine the combined load on the system? ______________________________________________

b. Explain the answer to part (a). ______________________________________________________________ ______________ ______________________________________________________________ ______________ Answer: a. No b. For loads that are not likely to be on at the same time, the smaller of the two loads may be omitted. See NEC 220.60.

550.

The total load of a cord-connected room air conditioner shall not exceed what percentage of a separate branch circuit? (Select the correct answer.) a. 75% b. 80% c.

125%

Answer: b. 80% 551.

The total load of a cord-connected air conditioner shall not exceed what percentage of a branch circuit that also supplies lighting? (Select the correct answer.) a. 50%

b. 75% c. 80%

Answer: a. 50%. NEC 210.23(A)(2) for 15- and 20-ampere branch circuits.

552.

a. Must an air conditioner installed in a window opening be grounded if a person on the ground outside the building can touch the air conditioner? __________________

b. What Code section governs the answer to part (a)? ____________________________ Answer: a. Yes © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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b. NEC 440.61, 250.110, 112, and 114 553.

A 120-volt air conditioner draws 13 amperes. What size is the circuit to which the air conditioner will be connected? _________________________________________________ Answer: Not less than a 20-ampere circuit 20 × 0.80 = 16 amperes; 15 × 0.80 = 12 amperes

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

554.

What is the Code requirement for receptacles connected to circuits of different volt- ages and installed in one building? ______________________________________________ Answer: The receptacles must be designed so that the attachment plugs are not interchangeable. See NEC 406.8.

555.

When a central air-conditioning unit is installed and the label states ―Maximum Size Fuse 50 Amperes,‖ is it permissible to connect the unit to a 50ampere circuit breaker? ________________________________________________________________ _______________ Answer: No, unless the branch circuit has both circuit breaker and fuse protection.

556.

When the nameplate on an air-conditioning unit states ―Maximum Size Fuse or HACR Circuit Breaker,‖ what type of circuit breaker must be used? _______________________ ________________________________________________________________ _______________ Answer: In the past, circuit breakers bearing the letters ―HACR‖ were required.

HACR circuit breakers were subjected to additional testing because of issues unique to air-conditioning equipment and other equipment having a hermetic motor compressor and/or large and small motors.

Manufacturers of this equipment submitted their equipment to UL or other recognized testing laboratory. The manufacturer would specify the size and type of branch-circuit overcurrent protection required.

Today, no additional testing is done. All conventional molded-case circuit breakers that are tested and listed to UL 489 may be used for the branch-circuit protection of HVAC units.

UL 1995, the standard for HVAC equipment is also phasing out the requirement for HACR circuit breakers.

Because of existing inventories of HVAC equipment and HACR-marked circuit breakers, it will probably take years for the letters ―HACR‖ to disappear from the scene. In the meantime, read and abide by the directions provided in the installation instructions and on the nameplate of the equipment.

557.

What section of the NEC prohibits the installation of Class 2 control circuit conduc- tors in the same raceway as the power conductors? ______________________________

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________________________________________________________________ _______________ Answer: NEC 725.136(A).

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558.

Match the following terms with the statement that most closely defines the term. Enter the letters in the blank space.

RLC ______________ a. The maximum ampere rating of the overcurrent protective device LRA ______________ b. The value used to determine the minimum ampere rating for the branch circuit BCSC _____________ c. The current of the compressor when the rotor is stalled or locked MOP ______________ d. A current value for the hermetic motor compressor that was determined by operating it at rated temperature, voltage, and frequency Answer: RLC = d, LRA = c, BCSC = b, MOP = a 559.

The disconnect for an air conditioner or heat pump must be installed ______________ of the unit.

Answer: In sight and readily accessible. NEC 440.14.

560.

NFPA 54, National Fuel Gas Code, states that regulator vents be located not less than ______________ ft. from a source of ignition.

Answer: 3

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 24: GAS AND OIL CENTRAL HEATING SYSTEMS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW 561.

The residence in this text is heated with (Select the correct answer.)

a. gas. ______________________________________________________________ _________

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b. electricity. ______________________________________________________________ ___ c. oil. ______________________________________________________________ __________ Answer: b. Electricity 562.

The NEC requires that the disconnecting means for central heating equipment, other than fixed electric space heating equipment, must comply with _________________ of _________________ _________________.

Answer: Part III; Article, 422.

563.

The NEC in _________________ requires that a central heating system be supplied by _________________ (a separate) (an individual) branch circuit.

(Select the correct answer.)

Answer: NEC 422.12; an individual (other than fixed electric space heating equipment).

564.

In a home, the low-voltage wiring between the thermostat and furnace is (Select the correct answer.) a. Class 1. ______________________________________________________________ _______ b. Class 2. ______________________________________________________________ _______ c. Class 3. ______________________________________________________________ _______ Answer: b. Class 2 565.

Class 2 circuits are _________________-limited and are considered to be _________________ from _________________ hazard and from _________________.

Answer: Power; safe; fire; electric shock

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

566.

The nameplate on a transformer will indicate whether or not it is a Class 2 transformer. (True) (False) (Select the correct answer.)

Answer: True.

567.

If Class 2 conductors are insulated for 150 volts, and the power conductors are insulated for 600 volts, does the Code permit pulling these conductors through the same raceway?

(Yes) (No) (Select the correct answer.) Give the NEC section number.

Answer: No. NEC 725.136.

568.

If you use 600-volt rated conductors for Class 2 wiring, does the Code permit pulling these conductors through the same raceway as the power conductors? (Yes) (No) (Select the correct answer.) Give the NEC section number. __________________________ Answer: No. NEC 725.136.

569.

The NEC is very strict about securing anything to electrical raceways.

Name the Code sections that prohibit this practice. NEC _________________________________________ ________________________________________________________________ _______________ Answer: NEC 725.143, and 300.11(C).

570.

Does the Code permit attaching the low-voltage thermostat cable to the EMT that brings power to a furnace? (Yes) (No) (Select the correct answer.) Give the NEC section numbers. ________________________________________________________________ ______ Answer: Yes. NEC 725.143. NEC 300.11(C)(2) permits the Class 2 control cable to be supported from the raceway that contains the power conductors to the equipment.

571.

Explain what a thermocouple is and how it operates. ______________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: A thermocouple consists of two dissimilar metals joined together so that a complete circuit is formed. Electric current will flow in the circuit when one junction is heated and the other junction remains cold.

572.

In multizone hydronic systems, a high-temperature control (______________) might be set to maintain the boiler water temperature to a specific temperature. Some multizone systems have one circulating pump and use electrically operated ______________ that open and close on command from the thermostat(s).

Answer: aquastat, valves.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 25: TELEVISION, TELEPHONE, AND L OW -VOLTAGE SIGNAL S YSTEMS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW TELEVISION CIRCUIT Note: Refer to the Code or plans where necessary.

Television Circuit 573.

How many television outlets are installed in this residence? _______________________ ________________________________________________________________ _______________ Answer: Twelve, however, with modern technology relying more heavily on wifi for television, discuss with students if this many TV outlets are truly needed. Ask how they might set this residence up instead.

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574.

Which type of television cable is commonly used and recommended? _______________ ________________________________________________________________ _______________ Answer: 75-ohm shielded coaxial cable 575.

What determines the design of the faceplates used? ______________________________ Answer: The design of other faceplates in the residence should be matched.

576.

What must be provided when installing a television outlet and 125-volt receptacle outlet in one wall box? _________________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: A barrier must be placed between the 120-volt section and the television section of the box so that the line voltage does not interfere with the low-voltage portion of the TV circuit and cause distortion.

577.

From a cost standpoint, which system is more economical to install: A master amplifier distribution system or a multiset coupler? Explain the basic differences between these two systems. ________________________________________________________________ __ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Answer: A multiset coupler distribution system is more economical than the master amplifier system. The master amplifier system is more expensive because it requires a 120-volt supply and, in general, is a more complex piece of equipment. In today’s high-tech world, changes happen quickly. Just about every community is served by companies that provide telephone, television, and Internet services. In new residential construction, the electrician will generally install the telephone, television, and Internet outlets as needed throughout the house, and also install the necessary cables to some common point in the house. This might be in the basement, the garage, a utility room, or at some common point where all interconnections will be made.

At this common point, the CATV serving company will bring in their cables, providing all connections to the interior wiring.

In the past, analog service was provided but is fast becoming incapable of carrying the amount of data now being used.

Because of the problem with analog service, serving companies are rapidly changing to digital high definition.

If the electrician has not installed the necessary telephone, television, and Internet wiring, the serving company will then do it.

578.

Digital satellite systems use an antenna that is approximately (18 in.

[450 mm]), (36 in. [900 mm]), and (72 in. [1.8 mm]) in diameter. (Select the correct answer.)

Answer: 18 in. (450 mm) 579.

List the requirements for cable television inside the house. ________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Code requirements are listed in outline form in the text. See also Article 820 of the NEC. 580.

Which article of the Code references the requirements for cable community television installation? ________________________________________________________________ ___ © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Answer: Article 820

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581.

It is generally understood that grounding and bonding together all metal parts of an electrical system and the metal shield of the cable television cable to the same grounding reference point in a residence will keep both systems at the same voltage level should a surge, such as lightning, occur. Therefore, if the incoming cable that has been installed by the CATV cable company installer has the metal shield grounded to a separate driven ground rod, does this installation conform to the NEC? _______________ ________________________________________________________________ _______________ Answer: No, see NEC 820.100(A) and (B). Note that (A) refers to 800.100 for requirements.

582.

All television satellites rotate above Earth in (the same orbit) (different orbits). (Select the correct answer.)

Answer: The same orbit 583.

Television satellites are set in orbit (10,000) (18,000) (22,245) miles above Earth, which results in their rotating around Earth at (precisely the same) (a different) rotational speed as the Earth rotates. This is done so that the satellite ―dish‖ can be focused on a specific satellite (once) (once a month) (whenever the television set is used). (Select the correct answers.)

Answer: 22,245; precisely the same; once 584.

Which section of the Code prohibits supporting coaxial cables from raceways that contain light or power conductors? NEC ________________________________________ Answer: NEC 820.133(B) 585.

When hooking up one CATV cable and another cable from an outdoor antenna to a receiver that has only one antenna input terminal, a(n) _________________ switch is usually installed.

Answer: A-B switch 586.

In your own words, explain the purpose of an intersystem bonding termination device. ________________________________________________________________ _______________ ________________________________________________________________ _______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Answer: The term Intersystem Bonding Termination is defined in NEC Article 100 as A device that provides a means for connecting intersystem bonding conductors for communications systems to the grounding electrode system.* 587.

For a new home, an intersystem bonding termination device is required (a) at the service equipment (b) at the subpanel. (Select the correct answer.)

Answer: a. at the service equipment. See NEC 250.94 SIGNAL SYSTEM Signal System 588.

What is a signal circuit? ________________________________________________________ ________________________________________________________________ _______________ Answer: Any electrical circuit that energizes signaling equipment, such as chimes 589.

What style of chime is used in this residence? ____________________________________ Answer: Flush (recessed) 590. a. How many solenoids are contained in a two-tone chime? _______________________ b. What closes the circuit to the solenoid of a chime?

Answer: a. Two b. Push button 591.

Explain briefly how two notes are sounded by depressing one push button (when two solenoids are provided). ________________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: First, one solenoid is energized when the button is pushed. The solenoid plunger strikes one tone bar and returns by spring action to rest against a felt pad so that it does not strike the second chime bar. When the second solenoid is energized, its plunger first strikes one tone bar. When it is deenergized, the plunger returns by spring action and strikes the second chime bar to give a 2-tone chime.

592. a. Sketch the symbol for a push button. ________________________________________ b. Sketch the symbol for a chime. ______________________________________________ Answer: a. b.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

593. a. At what voltage do residence chimes generally operate? _________________________ b. How is this voltage obtained? _________________________________________________ Answer: a. 16 volts b. By using a step-down transformer 594.

What is the maximum volt-ampere rating of transformers supplying Class 2 systems? ________________________________________________________________ _______________ Answer: 100 volt-amperes 595.

UL?

What two types of chime transformers for Class 2 systems are listed by

________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Inherently limited transformers, non-inherently limited transformers 596.

Is the extension chime connected with the front hall chime in series or in parallel? ________________________________________________________________ _______________ Answer: In parallel 597.

How many bell wires terminate at

a. the transformer? ____________________________________________________________ b. the front hall chime? ________________________________________________________ c. the extension chime? ________________________________________________________ d. each push button? __________________________________________________________ © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Answer: a. Two b. Nine c. Three d. Two

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

598.

a. What change in equipment may be necessary when more than one chime is connected to sound at the same time on one circuit?

______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ b. Why? ______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ Answer: a. It may be necessary to install a chime transformer of high capacity. b. Because more solenoids operating together draw more current. Also, more voltage drop and power loss can be expected owing to the use of more wire in the circuit. Ed = IR and W = I2R

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599.

What type of insulation is usually found on low-voltage wires? _____________________ Answer: Thermoplastic 600.

What size wire is installed for signal systems of the type in this residence? __________ Answer: 18 AWG wire 601.

a. How many wires are run between the front hall chime and the extension chime in the recreation room? ______________________________________________________

b. How many wires are required to provide a ―hot‖ low-voltage circuit at the extension chime? ______________________________________________________________ ______ Answer: a. Three b. Four

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602.

Why is it recommended that the low-voltage secondary of the transformer be run to the front hall chime location and separate 2-wire cables be installed to each push button? ________________________________________________________________ _______ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Because some chimes have low-voltage clocks and/or lights that require a ―hot‖ circuit 603.

a. Is it permissible to install low-voltage Class 2 systems in the same raceway or enclosure with light and proper wiring? ________________________________________

b. Which Code section covers this? ______________________________________________ Answer: a. No b. NEC 725.136(A) 604. a. Where is the transformer in the residence mounted? ___________________________ b. To which circuit is the transformer connected? _________________________________ Answer: a. In the workshop b. Circuit A17 605. a. How many feet of 2-conductor bell wire cable are required? _____________________ b. How many feet of 3-conductor bell wire cable are required? _____________________ Answer: a. 130 ft (40 m), 2-conductor bell wire cable. This is very approximate. b. 50 ft (15 m), 3-conductor bell wire cable. This is very approximate.

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606.

How many insulated staples are needed for the bell wire if it is stapled every 24 in. (600 mm)?

Answer: 60 (This is very approximate.)

607.

Should low-voltage bell wire be pulled through the same holes in studs and joists that also contain nonmetallic-sheathed cable?

Answer: No. This is an issue of the fact that the small conductors can be damaged under the pressure and weight of the larger cable.

608.

What section of the Code prohibits supporting fire alarm conductors from raceways that contain light or power conductors? NEC Answer: NEC 760.24 and 760.143

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609.

Complete this typical chime wiring diagram using colored pencils. The 2-wire, low-voltage cables contain one red and one white conductor. Use yellow to represent the white conductors.

Answer:

610.

What does the term ―Wi-Fi‖ stand for?

________________________________________________________________ _______________ Answer: Wireless local area network (WLAN) products that are based on the Institute of Electrical and Electronics Engineers’ (IEEE) 802.11 standards.

611.

A Wi-Fi system is (required) (optional). (Select the correct answer.)

Answer: Optional. No requirement is mentioned in the NEC or the text. © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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* Source NFPA 70-2023.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 26: SMOKE, HEAT, CARBON MONOXIDE ALARMS, AND SECURITY SYSTEMS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW 612.

In your own words, explain the terms alarm and detector.

________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: An alarm is the device that sounds a warning signal. A detector is the device that has a sensor that responds to a physical stimulus such as smoke, heat, carbon monoxide, or explosive gases. Most smoke alarms used in typical residential applications have the alarm and the detector in one device.

613.

The requirements for household fire alarm systems are found in what NFPA code and in what chapter of this code? ________________________________________________________________ _______________ Answer: NFPA 72, Chapter 29, of the National Fire Alarm and Signaling Code.

614.

Do heat alarms and carbon monoxide alarms take the place of smoke alarms? Explain.

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________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: No. Heat alarms and carbon monoxide alarms are installed in addition to smoke alarms.

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615.

Name two basic ways that smoke alarms are powered.

________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: AC/battery dual powered and battery only 616.

Name the two types of smoke alarms.

________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Photoelectric type and ionization type 617.

List the absolute minimum level of smoke alarm protection in a new onefamily dwelling. ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: 

One smoke alarm in each bedroom. If there are other sleeping areas, then a smoke alarm must also be installed in those other sleeping areas.



One smoke alarm outside of the bedrooms or other sleeping areas.

Generally, this is the hallway between the bedrooms.



One smoke alarm on each level (floor). This includes the basement—on the ceiling near the basement stairs.

618.

Select the correct answer from the following statements:

a. Smoke alarms installed in new one- and two-family homes must be battery-operated only, so as not to be affected by a power outage. b. Smoke alarms installed in new one- and two-family homes are to be dualpowered by a 120-volt circuit and a battery.

Answer: b. Smoke alarms installed in new one- and two-family homes are to be dual-powered by a 120-volt circuit and a battery.

619.

Select the correct answer from the following statements:

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a. Smoke alarms installed in new one- and two-family homes must be interconnected so that if any one of them is triggered, all other alarms will also sound off. b. Smoke alarms installed in new one- and two-family homes are not permitted to be interconnected so that each alarm will operate independently of all other alarms in the home.

Answer: a. Smoke alarms installed in new one- and two-family homes must be interconnected so that if any one of them is triggered, all other alarms will also sound off.

620.

Select the correct answer from the following statements:

a. Always install smoke and fire alarms in dead airspaces. b. Never install smoke and fire alarms in dead airspaces.

Answer: b. Never install smoke and fire alarms in dead airspaces.

621.

Select the correct answer from the following statements:

a. Mount wall-mounted smoke alarms so that the top edge is not more than 12 in. (305 mm) from the ceiling. b. Mount wall-mounted smoke alarms anywhere on the wall, but not lower than 36 in. (914 mm) from the ceiling.

Answer: a. Mount wall-mounted smoke alarms so that the top edge is not more than 12 in. (305 mm) from the ceiling.

622.

Cooking and baking in the kitchen can produce quite a bit of smoke. The best choice for a smoke alarm in the kitchen is the photoelectric type. The better choice would be to install a (heat alarm) (carbon monoxide alarm). (Select the correct answer.)

Answer: Heat alarm 623.

An important but often overlooked requirement in the National Fire Alarm and Signaling Code, NFPA 72, is that alarms must be replaced after being in service for (Select the correct answer.) a. not more than 5 years. b. not more than 10 years. c. not more than 15 years.

Answer: b. Not more than 10 years

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624.

Carbon monoxide is ______________________, and is ______________________, ______________________, and ______________________.

Answer: Highly poisonous; odorless; colorless; tasteless 625.

Select the correct answer from the following statements:

a. Carbon monoxide is heavier than air. b. Carbon monoxide will always rise to the ceiling. c. Carbon monoxide will drop to the floor. d. Carbon monoxide is about the same weight as air.

Answer: d. Carbon monoxide is about the same weight as air.

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626.

The wiring of more complex household fire alarm systems is covered in what article of the National Electrical Code? (Select the correct answer.) a. Article 725 b. Article 310 c. Article 760 Answer: c. Article 760 627.

Select the correct answer from the following statements:

a. Always connect a smoke alarm circuit to a power supply that has ground-fault circuit interrupter (GFCI) protection. b. Never connect a smoke alarm circuit to a power supply that has ground-fault circuit interrupter (GFCI) protection. c. It makes no difference whether the branch circuit is GFCI-or AFCI-protected because the alarms are required to have battery backup power. In the event of a loss of power for whatever reason, the alarms would still be operative.

Answer: b. Never connect a fire alarm circuit or system to a power supply that has ground-fault circuit interrupter (GFCI) protection. See NEC 760.41(B) and 760.121(B).

628.

Select the correct answer from the following statements:

a. Conductors for fire alarm systems are not permitted to be installed in the same raceways, cables, or electrical boxes as the light and power conductors. b. It is permissible to install fire alarm conductors in the same raceways, cables, or electrical boxes as the light and power conductors because the conductors for fire alarm systems covered in Article 760 are small and would easily fit into other electrical raceways and boxes.

Answer: a. Conductors for fire alarm systems are not permitted to be installed in the same raceways, cables, or electrical boxes as the light and power conductors. NEC 760.136.

629.

The Standard for Single- and Multiple-Station Alarms is UL _____________________. (Provide the standard number.)

Answer: UL 217 630.

When installing a fire alarm system or a complete security system package in a home, always follow the installation instructions from (Select the correct answer.)

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a. the manufacturer of the product and applicable codes. b. your neighbor because he knows a lot about codes and standards. c. the man at the home center who sold you the product.

Answer: a. the manufacturer of the product and applicable codes. NEC 110.3(B).

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631.

Residential sprinkler fire protection systems are required to be installed in compliance with the following (Select the best answer.) a. NFPA 13D b. IRC P2904 c. either NFPA 13D or IRC P2904 d. neither NFPA 13D nor IRC P2904 Answer: c. Either NFPA 13D or IRC P2904 Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 27: FEEDER AND SERVICE-ENTRANCE CALCULATIONS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the Code or the plans where necessary.

632.

According to NEC, the minimum-size service required for a one-family dwelling is _________________________________________________ amperes.

Answer: NEC 230.79(C); 100 amperes 633. a. What is the unit load per ft.2 for the general lighting load of a residence? ________ ______________________________________________________________ ______________ b. What are the demand factors for the general lighting load in dwellings? ______________________________________________________________ ______________ ______________________________________________________________ ______________ ______________________________________________________________ ______________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Answer: a. 3 volt-amperes per sq. ft (33 volt-amperes per square meter). See220.41. b. The first 3000 volt-amperes are calculated at 100% demand; from 3001 to 120,000 volt-amperes, at 35% demand; the remainder over 120,000 voltamperes, at 25% demand. See Table 220.42.

634.

a. What is the ampere rating of the circuits that are provided for the smallappliance loads? ______________________________________________________________ _______

b. What is the minimum number of small-appliance circuits permitted by the Code? ______________________________________________________________ ______________ Answer: a. 20 amperes. See NEC 210.11(C)(1). b. Two 20-ampere small appliance circuits, plus one 20-ampere laundry circuit.

See NEC 210.11(C)(1) and 210.11(C)(2).

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635.

Why is the air-conditioning load for this residence omitted in the service calculations? ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Because it is the smaller of the two loads (air conditioning and electric heating) and these loads are not likely to be operating at the same time. See NEC 220.60. Therefore, the smaller of the two loads may be omitted.

636.

What demand factor may be applied when four or more fixed appliances are connected to a service or feeder? (220.53) ________________________________________ ________________________________________________________________ _______________ Answer: 75% 637.

What load may be used for a single electric range rated at not over 12 kW? (Table 220.55) ________________________________________________________________ _______________ Answer: 8 kW 638.

What is the calculated load for an electric range rated at 16 kW? (Table 220.55) Show calculations.

Answer:

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

16 exceeds 12 kW by 4 kW; 4 × 5% = 20% 8 kW × 0.20 = 1.6 kW Thus, 8 + 1.6 = 9.6 kW 639.

What is the percentage of calculated load that is added to the service calculation when fixed electric heating is used in a residence? (220.51) ________________________________________________________________ _______________ Answer: 100% of the load for feeders and the service (NEC 220.51). The branch circuit conductors and overcurrent device are required to be rated not less than 125% load but the load is at 100% of the load[NEC 424.3(B)].

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640.

On what basis is the neutral conductor of a service entrance determined?

________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: On the maximum connected unbalanced load between the neutral and any one ungrounded conductor. NEC 220.61 641.

Why is it permissible to omit an electric space heater, water heater, and certain other 240-volt equipment when calculating the neutral service-entrance conductor for a residence? ________________________________________________________________ _____ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Because these loads are 240-volt equipment. Thus, the current of these loads will never be carried through the neutral conductor.

642.

a. What part of the NEC Article 220 contains an optional method for determining residential service-entrance loads? ___________________________________________

b. Is this section applicable to a multifamily residence? __________________________ Answer: a. NEC 220.82. Refer to Article 220, Part IV, for full details. b. No. One-family residence only. Refer to NEC 220.84 for multifamily dwellings.

643.

Calculate the minimum size of copper service-entrance conductors required for a residence with a floor area of 24 ft. × 38 ft. (7.3 m × 11.6 m). The dwelling will have: 

a 12-kW, 120/240-volt electric range.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding



a 5-kW, 120/240-volt electric clothes dryer consisting of a 4-kW, 240-volt heating element, a 120-volt motor, and 120-volt lamp that have a combined load of 1 kW.



a 2200-watt, 120-volt sauna heater.



six individually controlled 2-kW, 240-volt baseboard electric heaters.



a 12-ampere, 240-volt air conditioner.



a 3-kW, 240-volt electric water heater.



a 1000-watt, 120-volt dishwasher.



a 7.2-ampere, 120-volt food waste disposer.



a 5.8-ampere, 120-volt attic exhaust fan.

Determine the sizes of the ungrounded ―hot‖ conductors and the neutral conductor. Use Type THWN. Use 310.16.

Do not forget to include the required two 20-ampere small-appliance circuits and the laundry circuit.

The panelboard is marked for 75°C terminations.

You may use the blank Single-Family Dwelling Service-Entrance Calculation form in the Appendix of this text, or use the form as a guide to make your calculations in the proper steps.

Two _________________________________ AWG THWN ungrounded ―hot‖ conductors One _________________________________ AWG THWN or bare neutral conductor Answer: METHOD 1: ARTICLE 220, PART III. Note: Do these calculations using 3 volt-amperes per sq. ft. If you also want to do the calculations using 33 volt-amperes per square meter, that is optional. NEC 90.9 explains how metric measurements are handled in the NEC. Specifically, NEC 90.9(D) states that you are in compliance with the NEC using inch-pound or metric values.

General lighting load (NEC 220.12) 24 × 38 × 3 VA per sq. ft Laundry circuit (NEC 210.11(C)(2) and 220.52(B))

2736 VA 1500 VA

Small appliance load (NEC 210.11(C)(1) and 220.52(A))

3000 VA

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Total

7236 VA

Application of demand factors (Table 220.42) First 3000 at 100% 7236 – 3000 = 4236 VA at 35%

3000 VA 1483 VA

Net computed load for general lighting, laundry, and small appliances Range load (220.55)

4483 VA

Dryer (220.54)

5000 VA

Electric baseboard heaters at 100% (220.51)

12,000 VA

8000 VA

Air conditioner (omit per 220.60) 0 VA Total

25,000 VA

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Fastened in place appliances Sauna heater: 120 volts

2200 VA

Water heater: 240 volts

3000 VA

Dishwater: 120 volts

1000 VA

Food waste disposer: 7.2 amperes at 120 volts Attic exhaust fan: 5.8 amperes at 120 volts

864 VA 696 VA 7760 VA

Apply 75% demand factor per NEC 220.53 Total: 7760 × 0.75 = Add 25% of largest motor: 0.25 × 7.2 × 120 =

5820 VA 216 VA (See Note 1.)

Total computed load: 4483 + 25,000 + 5820 + 216 = 35,519 VA I=

W 35,519 = = 148 amperes E 240

The service-entrance panel is marked as having 75°C terminals.

Referring to 310.12, find that a 1 AWG THWN copper is suitable for a 150ampere service. If we chose to use the ampacities of Table 310.16, the conductor size would be a 1/0 AWG copper.

Neutral (grounded) conductor Small appliance, laundry, and general lighting after applying demand factor

4483 VA

Range, 8 kW at 70%, (NEC 220.61)

5600 VA

Dryer, 5 kw at 70%, (NEC 220.61)

3500 VA ________

Total

13,583 VA

Fastened in Place Appliances Sauna heater: 120 volts Dishwasher: 120 volts Food waste disposer: 7.2 amperes at 120 volts Attic exhaust fan: 5.8 amperes at 120 volts

2200 VA 1000 VA 864 VA 696 VA

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__________ 4760 VA

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Apply 75% demand factor per NEC 220.53 Total: 4760 × 0.75 = Add 25% of largest motor: 0.25 × 7.2 × 120 1.)

3570 VA 216 VA (See Note

Dryer heating element, electric heating, air conditioner, and water heater are 240-volt loads that can be omitted from the neutral calculation.

Total computed load on neutral: 13,583 + 3570 + 216 = 17,369 VA I

W 17,369   72 amperes E 240

We assume that the 120-volt loads are evenly divided between the two ungrounded ―hot‖ conductors.

In NEC 220.5(B), we ―round up‖ when the fractions of an ampere are 0.5 or larger. If less than 0.5 drop the fraction. In the above example, 72.37 is considered to be 72 amperes.

310.12(D) states that the grounded neutral service conductor is permitted to be smaller than the ungrounded conductors provided the requirements of these sections of the NEC are met: 

NEC 220.61 (Must be capable of carrying the maximum computed load between any ungrounded conductor and the neutral conductor.)



NEC 230.42 (Shall be of sufficient size to carry the computed loads.)

Referring to Table 310.16, we find that a 4 AWG THWN has an ampacity of 85 amperes.

Therefore, install a 4 AWG THWN or bare for the neutral conductor.

Referring to Table 250.66, install a 6 AWG copper grounding electrode conductor for 1 AWG service-entrance conductors.

Note 1: The student might question why an additional 25% of the largest motor (the air conditioning) was not included in the above calculation. This was omitted because the electric heat is so much larger than the air-conditioner load, and we are permitted to omit noncoincidental loads. We added 25% of the largest 120volt motor: the food waste disposer.

The largest motor can be difficult to determine because nothing is in place when service-entrance load calculations are made. It might be an air-conditioning or a heat pump. If the dwelling is cooled by an evaporative cooler, the largest motor might be a water pump motor, a large attic exhaust fan, a large food waste disposer, or a sump pump. © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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For simplicity, the food waste disposer motor was chosen for this calculation.

The 12-ampere air conditioning load in this question does not provide enough detailed information.

See Chapter 23 for a complete explanation of how air-conditioning current ratings are derived.

The calculation results in a 150-ampere service. Ask your students whether they would install a 150-ampere service or a 175-ampere or 200-ampere service.

Ask your students whether there are any local code requirements for a residential minimum size service entrance. Encourage discussion.

Note 2: For extra credit, or for more practice in making calculations, the instructor might wish to have students calculate this question using the Optional Method.

Note 3: When selecting conductors, always make sure of the temperature rating of the equipment, in this case the main panel. This is shown on the label of the equipment. Refer to NEC 110.14(C). This was covered in Chapter 8 of this text.

Note 4: If the service-entrance conductors will be subject to high ambient temperatures, it may be necessary to apply the correction factors found in Table 310.15(B)(1).

644.

Service-entrance conductors have an insulation that is rated 75°C are installed in an ambient temperature of 102°F. Since Table 310.16 is based on an ambient temperature of 86°F, what percent reduction is required to be applied to the conductor ampacity?

Answer: 0.88 See Table 310.15(B)(1).

STUDENT CALCULATIONS Note to instructor: A single-family dwelling service-entrance calculation form is in Appendix F of this text and may be copied for you to pass out multiple copies to your students. You can copy the line items on the front page and the explanation for the line items on the back side of the page.

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 28: INSTALLING FEEDERS AND SERVICE-ENTRANCE EQUIPMENT – GROUNDING AND BONDING TABLE OF CONTENTS Review .......................................................................................................................... 10

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REVIEW Note: Refer to the NEC, the text, and/or the plans where necessary.

645.

Define the Service Point. ________________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The service point is The point of connection between the facilities of the serving utility and the premises wiring.* For a typical underground service, the service point is in the meter base. For a typical overhead service, the service point is at the connection where the premise wiring service-entrance conductors are connected to the utility’s service-drop conductors. Refer to Definitions in the NEC. 646.

Define service-drop conductors. _________________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Service-drop conductors are The overhead conductors between the utility electric supply system and the service point.* The service drop is usually installed by the electric utility. Refer to Definitions in the NEC.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

647.

Who is responsible for determining the service location? ___________________________ Answer: The electric utility. They will know where and how they wish to supply the service to their customer.

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314

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

648.

a. The service head must be located (above) (below) the point where the service-drop conductors are spliced to the service-entrance conductors.

(Select the correct answer.)

b. What Code section provides the answer to part (a)?

Answer: a. Above b. NEC 230.54(C) 649.

What is a mast-type service entrance? ___________________________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The raceway containing the service-entrance conductors is run through the roof of a building to a height sufficient to obtain the necessary clearances of the service-drop conductors above the ground, fences, sidewalks, driveways, etc. See illustration in text.

650.

When a conduit is extended through a roof, when must it be supported by additional means, such as guy wires? ______________________________________________________ ________________________________________________________________ _______________ Answer: When the mechanical strength of the mast is not sufficient to support the weight of the service drop conductors. Depends upon the size of the conduit and the length of the service drop. A good rule of thumb is that anytime the service mast will extend more than 3 feet above the roof, you will need to verify if the mast strength is sufficient. The power company usually provides this information. See NEC 230.28. No other conductors are permitted to be attached to the mast.

651.

a. What size and type of conductors are installed for the service in this text? _______

______________________________________________________________ _____________ b. What size conduit is installed? ______________________________________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

c. What size grounding electrode conductor is installed? (not neutral) _____________ d. Is the grounding electrode conductor insulated, armored, or bare? ______________ Answer: Refer to the specifications. a. Two 2/0 AWG THWN, THW, or XHHW plus one 1 AWG neutral conductor b. A trade size 1 1 2 conduit is large enough for the service-entrance conductors.

If a service lateral is supplied by the electric utility, be sure to verify whether they have a minimum size and type of conduit for their conductors. c. 4 AWG copper d. Armored, though a bare copper grounding electrode conductor is typically installed to a concrete-encased grounding electrode.

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316

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

652.

How and where is the grounding electrode conductor attached to the water pipe? ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: The grounding electrode conductor is attached with a ground clamp to the metal water pipe supply on the first 5 ft (1.5 m) of where the piping enters the building, NEC 250.68©(1). In this residence, the water supply is from a deep well.

653.

What are the minimum distances or clearances for the following?

a. Overhead service conductor clearance over private driveway ____________________ b. Overhead service conductor clearance over private sidewalks ____________________ c. Overhead service conductor clearance over alleys ______________________________ d. Overhead service conductor clearance over a roof having a roof pitch of not less than 4/12 (Voltage between conductors does not exceed 300 volts.) ______________ e. Overhead service conductor horizontal clearance from a porch __________________ f. Overhead service conductor clearance from a fence that can be climbed on ______ Answer: a. 12 ft (3.7 m) b. 10 ft (3.0 m) c. 18 ft (5.5 m) d. 3 ft (900 mm). Can be reduced to 18 in. (450 mm) where the conductors pass over not more than 4 ft (1.2 m) of roof overhang. e. 36 in. (900 mm) f. 10 ft (3.0 m)

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317

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

654.

What is the minimum size ungrounded conductors using copper conductors that have Type THW insulation for the following residential electrical services? The terminals in the panelboard are marked 75°C. AMPERE RATING OF SERVICE

SERVICE-ENTRANCE CONDUCTORS SIZED PER TABLE 310.16

SERVICEENTRANCE CONDUCTORS SIZED PER 310.12

100 200 400

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Answer: AMPERE RATING OF SERVICE

SERVICE-ENTRANCE CONDUCTORS SIZED PER TABLE 310.16

SERVICE-ENTRANCE CONDUCTORS SIZED PER 310.12

100

3 AWG

4 AWG

200

3/0 AWG

2/0 AWG

400

Two 3/0 in parallel1

400 kcmil2

Note: 310.12 is for 120/240-volt, single-phase services and feeders. It also applies to two ungrounded and one grounded conductor feeders installed from 208Y/120-volt 3-phase, 4-wire systems. Some localities do not permit using this alternative sizing of service-entrance conductors.

1

By installing two raceways, no derating of the ampacity of the conductors is necessary.

2

Nothing in 310.12 explicitly permits connecting two 2/0 service-entrance conductors in parallel for a 400-ampere service. Verify any intention to do so with your local electrical inspector.

655.

What is the minimum size copper grounding electrode conductor for each of the following residential electrical services? Refer to Table 250.66. The ungrounded conductors are copper with Type THW insulation.

AMPERE RATING OF SERVICE

GROUNDING ELECTRODE CONDUCTOR WHEN THE SERVICE-ENTRANCE CONDUCTORS ARE SIZED PER TABLE 310.16

GROUNDING ELECTRODE CONDUCTOR WHEN THE SERVICE-ENTRANCE CONDUCTORS ARE SIZED PER 310.12

100 200 400 Answer: AMPERE RATING OF SERVICE

GROUNDING ELECTRODE CONDUCTOR WHEN THE SERVICE-ENTRANCE CONDUCTORS ARE SIZED

GROUNDING ELECTRODE CONDUCTORS WHEN THE SERVICE-ENTRANCE INDUCTORS ARE SIZED

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

PER TABLE 310.16

PER 310.12

100

8 AWG

8 AWG

200

4 AWG

4 AWG

400

2 AWG

1/0 AWG1

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320

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

Note: 310.12 is for 120/240-volt, single-phase residential services and feeders. It also applies to two ungrounded and one grounded conductor feeders installed from 208Y/120-volt 3-phase, 4-wire systems. This section does not apply to services and feeders other than residential.

1

Nothing in 310.12 explicitly permits connecting two 2/0 service-entrance conductors in parallel for a 400-ampere service. Verify any intention to do so with your local electrical inspector.

Grounding electrode conductors are sized according to 250.66.

When conductors are paralleled, an extra step is necessary. The note below the table states that for paralleled conductors, it is necessary to find the equivalent circular mil area of the conductors. The circular mil area of conductors is found in Table 8 of Chapter 9 of the NEC. The cross-sectional area of 3/0 AWG is 167,800 circular mils.

167,800 2 = 335,600 circular mils. Referring to Table 250.66, find that the minimum size grounding electrode conductor is 2 AWG copper.

656.

A surge protective device for the service is required to be of which of the following Types? (Select all correct answers.) a. Type 1

c. Type 3

b. Type 2

d. Type 4

Answer: 12, Type 1, Type3. This depends upon the local power company. The rule of thumb is eye level, normally 5 ft (1.5 m) to the center of the meter.

657.

What is the recommended height of a meter socket from the ground? _______________ 658.

a. Is the bare grounded neutral conductor of a service permitted to be buried directly in the ground? ______________________________________________________________

b. What section of the Code covers this? _________________________________________ Answer: a. Ys b. NEC 230.30. Check this out with the local inspector. There could be unusual soil conditions that might have a corrosive effect on bare copper.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

659.

How far must mechanical protection be provided when underground service conductors are carried up a pole? ________________________________________________ Answer: 8 ft (2.5 m). See NEC 300.5(D).

660.

a. A service disconnect is permitted to consist of not more than how many switches or circuit breakers? __________________________________________________________

b. Are these devices required to be in one enclosure? _____________________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

c. What type of main disconnect is provided in the residence in this book? __________ d. Does your city permit more than one service disconnect? _______________________ Answer: a. In general, one. However, the NEC will allow up to six service disconnects per service or set of service conductors. See NEC 230.71(B). b. No, in fact they are not permitted to be in the same enclosure. Each service disconnect must be in it’s own enclosure for safety reasons. See NEC 230.71(B). c. Two fusible switches are installed for the service disconnecting means.. See the Specifications in Appendix A for full details. d. Answer depends upon your local code requirements. Are they more stringent than the NEC? 661.

Complete the following table by filling in the columns with the appropriate information.

CIRCUIT AMPER CONDUCTO NUMBER POLES VOLTS R SIZE E RATING A. Living room receptacle outlets B. Workbench receptacle outlets C. Water pump D. Attic exhaust fan E. Kitchen lighting F. Hydromassage tub G. Attic lighting H. Counter-mounted cooking unit I. Electric furnace Answer: CIRCUIT

AMPERE POLES VOLTS

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CONDUCTO R

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

NUMBER

RATING

SIZE

A. Living room receptacle outlets

B17

15

1

120

14

B. Workbench receptacle outlets

A18

20

1

120

12

C. Water pump

A(5-7)

20

2

240

12

D. Attic exhaust fan

A10

15

1

120

14

E. Kitchen lighting

B7

15

1

120

14

F. Hydromassage tub

A9

15

1

120

12

G. Attic lighting

B10

15

1

120

14

H. Counter-mounted cooking unit

B(2-4)

40

2

240

8

I. Electric furnace

A(1-3)

70

2

240

4

662. a. What size conductors supply Panelboard A? _____________________________________ b. What size raceway? __________________________________________________________ c. Is this raceway run in the form of electrical metallic tubing or rigid conduit? d. What size overcurrent device protects the feeder conductors to Panelboard A? ____ ______________________________________________________________ ______________ Answer: a. 2 AWG Type THWN b. Trade size 1 c. Electrical metallic tubing (EMT) d. 125-ampere fuses in switch at service 663.

What size conductors supply Panelboard B? _______________ AWG __________________ a. What size raceway, if installed? _______________________________________________ b. Is this raceway run in the form of electrical metallic tubing or rigid metal conduit? electrical metallic tubing

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

c. What size overcurrent device protects the feeder conductors to Panelboard B? ____ Answer: 3 AWG a. Trade size 1 b. electrical metallic tubing c. 100 amperes 664.

How many electric meters are provided for this residence? _________________________ Answer: One 665.

a. According to the NEC, is it permissible to ground a residential rural electrical service to driven ground rods only when a metallic water system is available? _____________

______________________________________________________________ ______________ b. What sections of the Code apply? _____________________________________________ Answer: a. No b. NEC 250.50, 250.52(A)(1), 250.53(A)(2), 250.53(D)(2) 666.

What table in the NEC lists the sizes of grounding electrode conductors required for electrical services of various sizes? Table _________________________________________ Answer: Table 250.66

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

667.

NEC 250.53(D)(2) requires that a supplemental grounding electrode be provided if the available grounding electrode is: (Select the correct answer.) a. metal underground water pipe. b. building steel. c. concrete encased ground.

Answer: a. Metal underground water pipe 668.

Do the following grounding electrode conductors require mechanical protection? a. 8 AWG ______________________________________________________________ ______ b. 6 AWG ______________________________________________________________ ______ c. 4 AWG ______________________________________________________________ ______ Answer: Refer to NEC 250.64(B). a. Yes b. If free from physical damage, no. If subject to physical damage, yes. c. No, unless exposed to physical damage. This situation would not normally be found in a home, but certainly could be found in commercial and industrial applications.

669.

Why is bonding of service-entrance equipment necessary? ________________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Only overload protection is provided for the service-entrance conductors. See NEC 230.90. A fault on one or more of the service conductors in the service raceway, the meter base, or the main panel could result in very high fault current attempting to flow through metallic components. Proper bonding provides a low impedance fault-current path, rather than attempting to pass the

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326

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

fault current though loose locknuts, bushings, or eccentric and concentric knockouts. This could result in severe arcing and sparking. Proper bonding is essential.

670.

What special types of bushings are required on service entrances? __________________ ________________________________________________________________ _______________ Answer: Bonding bushings (grounding bushings) 671.

When insulated conductors 4 AWG or larger are installed in conduit, what additional provision is required on the conduit ends? _______________________________________ ________________________________________________________________ _______________ Answer: Insulated bushing must be provided. Use insulating bushings with double locknuts, combination insulating/metal bushings, insulating sleeves, or any other listed insulating means suitable for the purpose. Most electricians use combination bonding/insulating/metal bushings. See NEC 300.4(G).

672.

What minimum size copper bonding jumpers must be installed to bond properly the electrical service for the residence discussed in this text? __________________________ ________________________________________________________________ _______________ Answer: Minimum 4 AWG copper. NEC 250.90 states that Bonding shall be provided where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed.* NEC 250.28(D) tells us to size the main bonding jumper according to Table 250.102(C)(1). NEC 250.102(C) also tells us that the supply-side bonding jumper on the supply side of the service shall not be smaller than shown in Table 250.102(C)(1).

673.

a. Where is Panelboard A located? _______________________________________________

b. On what type of wall is Panelboard A fastened? ________________________________ c. Where is Panelboard B located? _______________________________________________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

d. On what type of wall is Panelboard B fastened? ________________________________ Answer: a. On the wall between the water heater and the workbench b. Concrete block c. On the wall in the Laundry room. d. Wood framed with sheetrock covering.

674.

When raceways pass through the wall from outside to inside, what measures must be taken to prevent air circulation through it? ________________________________________________________________ _______________ Answer: Sealed. NEC 300.7(A) 675.

Briefly explain why electrical systems and equipment are grounded. ________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Electrical systems are grounded to limit the voltage imposed by lightning, line surges, or unintentional contact with higher voltage lines, and that will stabilize the voltage to earth during normal operation, NEC 250.4(A)(1).

Non–current-carrying conductive materials enclosing electrical conductors or equipment are grounded to minimize the voltage to ground on that equipment, NEC 250.4(A)(2).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

676.

In general, systems are required to be grounded if it can be done so that the maximum voltage to ground does not exceed (Select the correct response.) a. 120 volts. b. 150 volts. c. 300 volts.

Answer: b. 150 volts 677.

To ensure a complete grounding electrode system (Select the correct response.) a. all grounding electrodes must be bonded together. b. all metal pipes and conduits must be isolated from one another. c. the service neutral is grounded to the water pipe only.

Answer: a. All grounding electrodes that are present at the service location must be bonded together to create a grounding electrode system. (NEC 250.50) 678.

When used as service equipment, a panelboard (load center) must be _______________ that it is suitable for use as service equipment, 230.66. If the panelboard (load center) contains the main service disconnect, it must be clearly marked _______________ _______________, 230.70(B).

Answer: Marked to identify it as being suitable for use as service equipment.

Typical markings may include MAIN DISCONNECT, MAIN SERVICE DISCONNECT, MAIN SWITCH. 679.

Here are five commonly used terms in the electrical industry. Enter the letter of the term that corresponds to its definition. a. Grounding electrode conductor b. Main bonding jumper

__________ The neutral conductor in a 120/240V single phase system.

d. Equipment grounding conductor

__________ The term used to define under-ground service-entrance conductors that run between the meter and the utilities connection.

e. Underground service conductors (Service Point at transformer)

__________ The conductor (sometimes a large threaded screw) that connects the neutral bar in the

c. Grounded circuit conductor

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 28: Installing Feeders and Service-Entrance Equipment – Grounding and Bonding

service equipment to the serviceentrance enclosure. __________ The conductor that runs between the neutral bar in the main service equipment to the grounding electrode (water pipe, ground rod, etc.). __________ The bare copper conductor found in nonmetallicsheathed cable.

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330

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 29: Overcurrent Protection—Fuses and Circuit Breakers

Answer: c, e, b, a, d

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331

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 29: Overcurrent Protection—Fuses and Circuit Breakers

680.

The electrician mounted the disconnect switch for a central airconditioning unit 8 ft. (2.5 m) above the ground. This was easy to do because the electrician only had to run the conduit across the ceiling joists in the basement, through the outside wall, and directly into the back of the disconnect switch. The electrical inspector turned the job down, citing NEC, which requires that the disconnecting operating handle must not be higher than ____________________ above the ground.

Answer: NEC 404.8(A); 6' 7" (2.0 m). Also see the NEC 440.14 requirement that the disconnect be within sight and readily accessible. The definition of readily accessible is Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to take actions such as to use tools (other than keys), to climb over or under, to remove obstacles, or to resort to portable ladders, and so forth.* 681.

a. According to the NEC definition of a wet location, a basement cement wall that is in direct contact with the earth is considered to be a wet location.

A panelboard mounted on this wall must have at least ( 1 4 in.) ( 1 2 in.) (1 in.) space between the wall and the panel. (Select the correct answer.)

b. How is this required spacing accomplished? ___________________________________ ______________________________________________________________ ______________ Answer: a.

1

4

in. (6 mm)

b. All metal panelboards and disconnect switches that are identified for wet locations have the necessary 1 4 -in. projections on their mounting holes.

Some electricians prefer to mount a piece of 3 4 -in. plywood to the wall behind the panel. If large enough, this makes for easy mounting of the panelboard and any other panel controls, relays, or electrical equipment that might be needed next to the panelboard.

682.

When using rebars as the concrete-encased electrode, the rebars must be (Select the correct answer.) a. insulated with plastic material so they will not rust, or b. bonded together by the usual steel tie wires or other effective means.

Answer: b. When using rebars as the concrete-encased electrode, the rebars must be bonded together by the usual steel tie wires or other effective means.

NEC 250.52(A)(3).

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332

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 29: Overcurrent Protection—Fuses and Circuit Breakers

683.

The circuit directory in a panelboard (may) (shall) be filled out according to NEC ____________________. Select the correct answer and enter the correct NEC section number.

Answer: Shall, NEC 110.22, 408.4.

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333

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 29: Overcurrent Protection—Fuses and Circuit Breakers

684.

A main service panel is located in a dark corner of a basement, far from the base- ment light. In your opinion, does this installation meet the requirements of 110.26(D)? Explain your answer. ___________________________________________________________ ________________________________________________________________ _______________ Answer: No. Illumination is required for all working spaces about service equipment and panelboards that are installed indoors so this equipment can be worked on safely if necessary.

685.

Does the electric utility in your area allow the location of the meter to be on the back side of a residence? ____________________________________________________________ Answer: The answer to this question will vary depending upon the local electric utility regulations.

686.

An equipment grounding conductor (is) (is not) required to be installed with feeder conductors to an outbuilding that is supplied by the service at the dwelling. (Select the correct answer.)

Answer: yes 687.

A ground rod is driven below the meter outside of the house. A grounding electrode conductor connects between the meter base and the ground rod. The ground clamp is buried under the surface of the soil. This is permitted if the ground clamp is for direct burial according to NEC. Answer: Listed; 250.70.

688.

Copper-coated steel ground rods are the most commonly used grounding electrodes. These rods are required to: a. if not listed, be at least ______________ in. (______________ mm) in diameter, 250.52(A)(5). b. be driven to a depth of at least ______________ft. (______________m) unless solid rock is encoun- tered, in which case the rod may be driven at a ______________° angle or may be laid in a trench that is at least ______________ft. (______________m) deep, 250.53(G). c. be separated by at least ______________ft. (______________m) when more than one rod is driven, 250.53(A)(3). d. have a ground resistance of not over ______________ ohms for one rod, 250.53(A)(2) Exception.

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334

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 29: Overcurrent Protection—Fuses and Circuit Breakers

Answer: a.

5

8

in. (15.87 mm), unless listed.

b. 8 ft (2.44 m); 45°; 2 1 2 ft (750 mm). c. 6 ft (1.8 m). d. 25 ohms.

689.

What section of the Code does not allow the use of sheet metal screws as a means of attaching grounding conductors to enclosures? NEC ____________________________ Answer: NEC 250.8. All connection devices must be listed. Sheet metal screws are not listed.

690.

Which section of the NEC prohibits using the space below and in front of an electrical panel as storage space? NEC ___________________________________________________ Answer: NEC 110.26(B) 691.

What section of the NEC prohibits using an underground metal gas pipe as the groundingelectrode for an electrical service? ______________________________________________ Answer: NEC 250.52(B)(1) 692.

When wiring a gas furnace, what additional steps, if any, are necessary in order to make sure that the gas piping supplying the furnace is adequately bonded? Explain. ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: Verify that the gas piping is in good electrical contact with the frame of the furnace that is grounded by the equipment grounding conductor that is run with the branch circuit. NEC 250.104(B) states that the equipment grounding conductor in the branch-circuit wiring is an acceptable bond. This could be EMT, the metal armor or equipment grounding conductor of Type AC or Type MC cable, or the equipment grounding conductor in nonmetallic-sheathed cable. See NEC 250.118 for a list of other acceptable equipment grounding conductors.

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335

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 29: Overcurrent Protection—Fuses and Circuit Breakers

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 29: OVERCURRENT PROTECTION—FUSES AND CIRCUIT BREAKERS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW 693.

What is the minimum size service for a one-family dwelling? ______________________ Answer: 100 amperes, 230.79(C) 694.

a. What is a Type S fuse? ______________________________________________________

______________________________________________________________ ______________ b. Where must Type S fuses be installed? _______________________________________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ Answer: a. A Type S fuse is a plug fuse that is nontamperable and noninterchangeable because of its special design. An adapter is inserted into the Edison-base fuseholder of the ampere rating of the Type S fuse to be installed. See NEC 240.53, 240.54. b. Edison-base fuses are permitted for replacement use where there is no evidence of overfusing or tampering, so Type S fuses are required for all new installations. NEC 240.51(B).

695.

a. What is the maximum voltage permitted between conductors when using plug fuses?

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 29: Overcurrent Protection—Fuses and Circuit Breakers

______________________________________________________________ ______________ ______________________________________________________________ ______________ b. Are plug fuses (Type S) permitted to be installed in a switch that disconnects a 120/240-volt clothes dryer? __________________________________________________ ______________________________________________________________ ______________

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337

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 29: Overcurrent Protection—Fuses and Circuit Breakers

c. Give a reason for the answer to (b). __________________________________________ ______________________________________________________________ ______________ ______________________________________________________________ ______________ Answer: a. Not over 125 volts between conductors unless the circuit has a grounded neutral and operates at not more than 150 volts to ground, NEC 240.50. b. Yes c. Because the voltage to ground does not exceed 150 volts.

696.

Will a 20-ampere, Type S fuse fit properly into a 15-ampere adapter? ________________ Answer: No. NEC 240.53(A) and (B).

697.

A time-delay, dual-element fuse will hold 500% of its rating for approximately (5 seconds) (10 seconds) (20 seconds). (Select the correct answer.)

Answer: 10 seconds 698.

What part of a circuit breaker causes the breaker to trip

a. on an overload? __________________ b. on a short circuit? ___________________ Answer: a. The bi-metal element b. The magnetic component 699.

What is meant by an ambient-compensated circuit breaker? _______________________ ________________________________________________________________ _______________ ________________________________________________________________ _______________ ________________________________________________________________ _______________

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338

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 29: Overcurrent Protection—Fuses and Circuit Breakers

Answer: A circuit breaker has two thermal elements. One element heats as a result of current passing through the element in addition to the heat of the surrounding air. The other element heats from the surrounding air only. The actions of these two elements oppose each other. This opposing action stabilizes the tripping point so that the current through the tripping element is the only factor that causes the breaker to trip.

700.

List the standard rating of fuses and circuit breakers up to and including 100 amperes. ________________________________________________________________ _______________ ________________________________________________________________ _______________ Answer: For fuses and circuit breakers: 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100. Additional standard ratings for fuses are: 1, 3, 6, and 10. See NEC 240.6(A) and Table 240.6(A).

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339

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 29: Overcurrent Protection—Fuses and Circuit Breakers

701.

When hooking up a 240-volt electric baseboard heater, you should use (Select the correct answer.) a. a 2-pole circuit breaker. b. two single-pole breakers and a handle tie.

Answer: Both a and b are acceptable. In 240.15(B)(1) and 240.15(B)(2), permission is given to use handle ties under certain conditions. The question asks about a 240-volt, 2-wire branch circuit to supply a baseboard electric heater.

Because the electrical system in a home is a grounded system, 240.15(B)(2) gives permission to use a handle tie. Handle ties are required to be identified and are available as an accessory from the circuit breaker manufacturer.

The preferred method certainly is to use a 2-pole circuit breaker.

702.

State four possible combinations of service equipment that meet the requirements of 110.9 and 110.10 of the Code. a. ________________________ _ b. ________________________ _ c. ________________________ _ d. ________________________ _

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340

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

Answer: Four possible combinations of service equipment that meet the requirements of 110.9 and 110.10 of the Code. a. Fully Rated: Fused main/fused branch circuits. All have interrupting rating adequate for the available fault current. b. Series Rated: Fused main/circuit breaker branch circuits. Has current-limiting fuses for the mains, and lower interrupting rated breaker for the branches. c. Fully Rated: Breaker main/breaker branch circuits. All have interrupting rating adequate for the available fault current. d. Series Rated: Breaker main/breaker branch circuits. As both open under a fault condition the dynamic impedances of the arcs inside both main and branch breaker are in series. The current that they are called upon to interrupt is within the limits of their capability. This is the most readily available and most commonly used type of panelboard (loadcenter) today.

Be sure to check the marking in the panelboard for its short-circuit current rating.

One way to be sure of a safe installation is to call the electric utility and ask, ―What is the available short-circuit current at my service?‖ The company will be happy to provide you with this information.

703.

Which Code section states that all overcurrent devices must have adequate interrupting ratings for the available fault current to be interrupted? _________________________________________________________________ ______________ Answer: NEC 110.9

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341

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

704.

All electrical components have some sort of ―withstand rating.‖ The NEC and UL Standards refer to this as the component’s short-circuit current rating.

This rating indicates the ability of the component to withstand a specified amount of fault current for the time it takes the overcurrent device upstream of the component to open the circuit. NEC _______________ refers to short-circuit current rating.

Answer: NEC 110.10 705.

Arc-fault damage is closely related to the value of ________________________________.

Answer: Ampere-squared seconds (I2t) 706.

The utility company has provided a letter to the contractor stating that the available fault current at the line side of the main service-entrance equipment in a residence is 17,000 amperes RMS symmetrical, line to line. In the space following each statement, write in ―Meets Code‖ or ―Violation‖ of 110.9 and 110.10 of the Code. a. Main breaker has a 10,000-ampere interrupting rating; branch breakers have a 10,000-ampere interrupting rating. ____________________________________________ b. Main current-limiting fuse has a 200,000-ampere interrupting rating; branch breakers have a 10,000-ampere interrupting rating. The panel is marked ―Series-Rated.‖ ______________________________________________________________ _______ c. Main breaker has a 22,000-ampere interrupting rating; branch breakers have a 10,000-ampere interrupting rating. The panel is marked ―SeriesConnected.‖ ______________________________________________________________ ______________ Answer: a. Violation b. Meets Code c. Meets Code 707.

NEC ______________________ generally prohibits the connecting of fuses and/or circuit breakers into the grounded circuit conductor.

Answer: NEC 240.15(A), 240.22

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

708.

In general, overcurrent protective devices are inserted where the conductor receives its ________________________________________________________________ ____________ Answer: Supply, NEC 240.21.

709. a. Does the NEC permit panelboards to be installed in clothes closets? _____________ b. Does the NEC permit panelboards to be installed in bathrooms? _________________ Answer: a. No. NEC 240.24(D). b. No, not in dwelling units, dormitories and guest rooms or guest suites. NEC 240.24(E).

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343

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

710.

Overcurrent devices must be accessible. (True) (False) (Select the correct response.)

Answer: True. NEC 240.24(A).

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 30: SWIMMING POOLS, SPAS, HOT TUBS, HYDROMASSAGE BATHS, AND ELECTRICALLY P OWERED POOL LIFTS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the Code or the plans where necessary.

711.

Most of the requirements for the wiring of swimming pools are covered in NEC article ________________________________________________________________ ____________ Answer: Article 680. This article contains special requirements unique to swimming pools, spas, hot tubs, and similar water-related equipment. These requirements supercede and/or are in addition to the general Code requirements found in other articles of the NEC. 712.

People in swimming pools are particularly vulnerable to electric shock due to mixing _____________, _____________, and _____________ in the same environment.

Answer: people, water, electricity 713.

Name the two ways in which a person may sustain an electrical shock when in a pool. a. ______________________________________________________________ ____________ b. ______________________________________________________________ ____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

Answer: a. By actually touching a ―live‖ conductor or ―live‖ equipment. b. From the voltage gradients present in the pool water resulting from a ―live‖ conductor or ―live‖ equipment falling into the water.

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345

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

714.

Using the text, the Plans in the back of this text, and the NEC, determine whether the following items must be bonded together and connected to the equipotential zone. Place an ―X‖ in the correct space.

a. Wet-and-dry niche luminaires b. Electrical equipment located within 5 ft.

(1.52 m) of inside walls of pool c. Electrical equipment located within 10 ft.

(3.0 m) of inside walls of pool d. Recirculating equipment and pumps e. Luminaires and ceiling fans installed more than 15 ft. (4.5 m) from inside walls of pool f. Junction boxes, transformers, and GFCI enclosures that contain conductors that supply wet-niche luminaires g. Panelboards that supply the electrical equipment for the pool h. Panelboards 20 ft. (6.0 m) from the pool that do not supply the electrical equipment for the pool

True

False

________ __

_______ __

________ __

_______ __

________ __ ________ __

_______ __ _______ __

________ __

_______ __

________ __

_______ __

________ __

_______ __

________ __

_______ __

Answer: a. True b. True c. False d. True e. False f. True g. True h. False

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346

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

715.

It is permitted to run other conductors in the same conduit as the GFCIprotected conductors that run to underwater luminaires. (True or False) (Select the correct answer.)

Answer: False. NEC 680.23(F)(3). There are a few exceptions.

716.

NEC ________________________ regulates the burial depth of wiring methods around a pool.

Answer: NEC 680.11

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347

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

717.

What is the purpose of grounding and bonding around a swimming pool? ___________ ________________________________________________________________ _______________ Answer: NEC 250.4(A)(2): Grounding of Electrical Equipment. Normally non– current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials. * NEC 250.4(A)(3): Bonding of Electrical Equipment. Normally non–currentcarrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path. * 718.

Does the NEC require that, after all of the metal parts of a swimming pool are bonded together to form a common grounding grid, this grid must be connected to a ground- ing electrode? ________________________________________________________________ _ Answer: No. NEC 680.26(B).

719.

Are conductors permitted to be run above the pool? Explain. ______________________ ________________________________________________________________ _______________ Answer: Yes. Table 680.9(A) provides the minimum clearances that must be maintained.

720.

What is the closest distance from the inside wall of a pool that a receptacle may be installed? ________________________________________________________________ _____ Answer: NEC 680.22(A)(1). The general rule is that the 125-volt, 15- or 20ampere receptacle connected to a general purpose branch circuit be located not less than 6 ft (1.83 m) from the inside walls of the pool.

NEC 680.22(A)(2), for a receptacle that provides power for a circulating pump for a permanently installed pool is required to be located not less than 6 ft (1.83 m) from the inside walls of the pool.

NEC 680.22(A)(3). For other receptacles, not less than 6 ft. (1.83 m).

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

721.

Receptacles located within 20 ft. (6.0 m) from the inside wall of a pool must be_________________ protected.

Answer: GFCI protected, NEC 680.22(A)(4).

722.

Luminaires installed above a new outdoor swimming pool must be mounted not less than (10 ft. [3.0 m]) (12 ft. [3.7 m]) above the maximum water level. (Select the correct answer.)

Answer: 12 ft (3.7 m). NEC 680.22(B)(1).

723.

Junction boxes and enclosures for transformers and GFCIs have one thing in common. They all (are made of brass) (have threaded hubs) (must be mounted at least 8 in.

[200 mm] above the deck). (Select the correct answer.)

Answer: Have threaded hubs. NEC 680.24(A) and (B).

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349

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

724.

For indoor spas and hot tubs, the following statements are either true or false. Check one. Refer to 680.43(A), (B), and (C).

True a. Receptacles may be installed within 5 ft. (1.5 m) from the edge of the spa or hot tub. _________

_________

b. All receptacles within 10 ft. (3.0 m) of the spa or hot tub must be GFCI-protected. _________

_________

c. Any receptacles that supply power to pool equipment must be GFCI-protected. _________

_________

d. Wall switches must be located at least 5 ft. (1.5 m) from the pool. _________

_________

False

e. In general, luminaires above a spa are required to be not less than 7 ft. 6 in. (2.3 m) above the maximum water level if the circuit is GFCI-protected. _________ _________ Answer: NEC 680.43(A), (B), and (C) a. False (Between 6 ft (1.83 m) and 10 ft (3.0 m)). b. True c. True d. True e. True 725.

Bonding and grounding of electrical equipment in and around spas and hot tubs (is required by the NEC) (is decided by the electrician). (Select the correct answer.)

Answer: Is required by the NEC 726.

Where a spa or hot tub is installed in an existing bathroom or other suitable location, an existing receptacle outlet within 5 ft. (1.5 m) of the tub is permitted to remain, but only if the circuit feeding the receptacle has ___________________________ protection.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

Answer: GFCI protection. See NEC 680. There 43(A)(2). is no exception for existing receptacles. All 125-volt receptacles rated 30 amperes or less within 10 ft (3.0 m) from the inside wall of the spa or hot tub must be GFCI protected. Any existing non–GFCI-protected receptacles will have to be changed.

727.

Underwater pool luminaires are required to be installed so that the top of the lens is not less than ________________ in. below the normal water line unless they are listed for a lesser depth.

Answer: 18 in. (450 mm), NEC 680.23(A)(5).

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351

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

728.

a. Hydromassage bathtubs and their associated electrical components (shall) (shall not) be protected by a GFCI. (Select the correct answer.)

b. All receptacles located within 6 ft. (1.83 m) of a hydromassage tub (shall) (shall not) be protected by a GFCI. (Select the correct answer.)

Answer: a. Shall; NEC 680.71. b. Shall; NEC 680.71. * Source NFPA 70-2023 729.

The risks associated with voltage gradients in pools can create a shock hazard resulting in immobilization, resulting in drowning and potential electrocution. The pool walls and bottom are assumed to be part of the ___________________________ and at ground, or zero, potential.

Answer: equipotential grid 730.

Not considering exceptions, electrically power pool lifts are required to be ________________, ________________, and ________________ for swimming pool and spa use.

Answer: listed, labeled, identified 731.

Junction boxes connected to a conduit that extends directly to a forming shell for a luminaire that operates above the low-voltage contact limit is required to be installed: (Select the correct answer.) a. So the bottom is not less than 4 in. above the maximum water level b. So the top is not less than 8 in. above the maximum water level c. So the inside bottom is not less than 4 in. above the deck level. d. So the top is not less than 8 in. above the deck level.

Answer: c. So the inside bottom is not less than 4 in. above the deck level.

732.

Which of the following wiring methods IS NOT permitted in areas that are defined as corrosive? (Select the correct answer.) a. Electrical Metallic Tubing b. Rigid Metal Conduit c. Intermediate Metal Conduit d. Rigid Polyvinyl Chloride Conduit

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

Answer: a. Electrical Metallic Tubing 733.

Perimeter surfaces within 3 ft. (900 mm) of the inside walls of the pool are required to be bonded by ________________, ________________, or ________________.

Answer: structural reinforcing steel, copper ring, copper grid

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353

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

734.

If a hydromassage bathtub is cord-and-plug connected with access through a service access opening, the receptacle face is required to be ___________________________ and ___________________________.

Answer: within direct view, not more than 12 in. from the opening Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 31: W IRING FOR THE FUTURE: HOME AUTOMATION SYSTEMS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the Code or the plans where necessary.

735.

Name two of the organizations that are involved in standards or installation requirements for home automation systems: ___________________________________ ________________________________________________________________ _____________ Key is variable. See the list on Page 693.

Answer: The answer is variable. See the list on Page 693.

736.

Infrared controllers transmit _____________________. Key: line of sight

Answer: Beams of infrared light waves.

737.

One type of home automation system is referred to as (Select the correct answer.) a. X10. b. X20. c. HAS. Answer: a. X10 738.

When using an X10 system, which of the following statements is most correct? a. A totally independent wiring system must be installed.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

b. The devices generally are ―plug­and­play‖ (PnP), requiring no additional wiring. c. An X10 system is ideally suited for installations in new construction.

Answer: b. The devices generally are ―plug-and-play‖ (PnP), requiring no additional wiring.

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355

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

739.

A home automation system that requires a totally separate wiring system is referred to as a. an X10 system. b. a structured system. c. a DC-powered system.

Answer: b. A structured system 740.

The most recommended ―category­rated‖ cable for wiring from various outlets back to the main ―service­center‖ for the interconnection of computers is (Select the correct answer.) a. Category 1. b. Category 2. c. Category 3. d. Category 5e.

Answer: d. Category5e 741.

When installing Category 5–rated cable, the minimum bending radius generally recommended is (Select the correct answer.) a. 4 times the diameter of the cable. b. 6 times the diameter of the cable. c. 10 times the diameter of the cable.

Answer: a. 4 times the diameter of the cable 742.

When installing coaxial cable, the minimum bending radius generally recommended is (Select the correct answer.) a. 4 times the diameter of the cable. b. 6 times the diameter of the cable. c. 10 times the diameter of the cable.

Answer: c. 10 times the diameter of the cable 743.

When selecting cables for a structured wiring system or computer hookups, the best choice is to select a cable that has (Select the correct answer.) a. untwisted pairs of conductors. © 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

b. twisted pairs of conductors.

Answer: b. Twisted pairs of conductors.

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357

Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

744.

Match each of the following terms with its description by entering the number of the correct definition in the blank space provided. a. RG

_______ _

1. cycles per second

b. RJ

_______ _

c. bps

_______ _

3. registered jack

d. mbps

_______ _

4. fiber optic

e. Hz

_______ _

5. bits per second

f. bit

_______ _

6. shielded twisted pair

g. UTP

_______ _

7. radio grade

h. FO

_______ _

8. megabits per second

i. STP

_______ _

9. unshielded twisted pair

2. the smallest unit of measurement in the binary system

Answer: a.

7

RG means ―radio grade.‖

b.

3

RJ means ―registered jack.‖

c.

5

bps means ―bits per second.‖

d.

8

mbps means ―megabits per second.‖

e.

1

Hz (Hertz) means ―cycles per second.‖

f.

2

bit means ―the smallest unit of measurement in the binary system.‖

g.

9

―UTP means unshielded twisted pair‖

h.

4

―FO means fiber optic‖

i.

6

―STP means shielded twisted pair‖

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 32: STANDBY POWER SYSTEMS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the Code or plans where necessary.

745.

The basic safety rule when working with electricity is to ________________________ ________________________________________________________________ ____________ Answer: Turn the power off and establish an electrically safe work condition.

See Chapter 1 and NFPA 70E. 746.

Where would the logical location be for running a portable generator?

________________________________________________________________ ____________ Answer: Outside in open air 747.

The best advice to follow is to always use (listed) (cheapest) (smallest) equipment. (Select the correct answer.)

Answer: Listed. That way you are assured that the products safety issues have been tested and verified by a recognized testing laboratory. After passing such tests, the product is then ―listed.‖ 748.

How would you define the term standby power? _______________________________ ________________________________________________________________ ____________ Answer: Standby power provides electrical power in the event of a power outage.

749.

Describe in simple terms the three types of standby power systems.

________________________________________________________________ ____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

Answer: _________ The simplest standby power system is a motor/generator set that has a receptacle mounted on it. To operate in the event of a power outage, the gen set is placed outside in open air and started. An extension cord is plugged into the receptacle on the gen set to operate whatever electrical load is needed— within the load limitations of the generator’s rating. _________ The next step up in standby power is a motor/generator, simple transfer switch, critical power (generator) panel, power inlet receptacle, and a power cord between the gen set and the power inlet. To operate in the event of a power outage, the gen set is placed outside in open air and manually started. A power cord is connected between the gen set and the power inlet receptacle.

The transfer switch is manually switched over to standby power. This standby power position connects the critical (generator) panel supplying only those branch circuits preselected as being critical to be energized during a power outage. _________ The top-of-the-line standby power system is one that has all components permanently installed. The gen set automatically starts up in the event of a power outage, an automatic transfer switch transfers preselected loads to be supplied during the power outage and shuts down when the normal power is restored.

750.

Is it permitted to ground the neutral conductor of the standby generator to the metal en closure of the generator, transfer switch, or critical (generator) panelboard? Explain. ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: The answer to this simple question is fairly complex and it depends on what type of generator is installed. Fifteen kW and smaller generators are produced with the neutral bonded to the frame or floating (isolated from the frame). The general rule in NEC 250.34(C) is the neutral is to be bonded to the frame of the portable generator if it is a component of a separately derived system. See the following table.

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

System

Permitted to ground (bond) the neutral of the standby generator to the frame of: Generator

Portable Generator Permanently Installed Generator

Required Yes, if separately derived, No if not separately derived

Transfer Switch No

Panelboard

No

No

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No

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

751.

Briefly explain the function of a transfer switch.

________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: To provide a means of manually or automatically transferring the selected branch circuits, feeder or service to a standby generator in the event of a power outage 752.

When a transfer switch transfers to standby power, the electrical connection inside the switch: (Select the correct answer.) a. maintains connection to the normal power supply as it makes connection to the standby power supply. b. breaks the connection to the normal power supply before it makes connection to the standby power supply.

Answer: b. Breaks the connection to the normal power supply before it makes connection to the standby power supply 753.

A typical transfer switch for residential application is: (Select the correct answer.) a. a 4-pole, double pole switch (DP). b. a double-pole, double-throw switch (DPDT). c. a single-pole, double-throw switch (SPDT). d. a double-pole, single-throw switch (DPST).

Answer: b. a double-pole, double-throw switch (DPDT) 754.

The technical NEC term for a system in which the neutral conductor is switched by the transfer equipment is referred to as (Select the correct answer.) a. a separately derived system. b. a nonseparately derived system.

Answer: a. A separately derived system

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

755.

The NEC requires that a ___________________________ means be provided for standby power systems. In the case of portable gen sets, this might be as simple as pulling out the plug on the extension cord that is plugged into the receptacle on the gen set. For permanently installed standby power generators, this might be on the gen set and/or separately provided inside or outside of the home.

Answer: Disconnecting

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

756.

The conductors running from a permanently installed standby power generator to the transfer switch shall not be less than (100%) (115%) (125%) of the generator’s output rating if overcurrent protection of the conductors is not provided at the generator. (Select the correct answer.)

Answer: 115% 757.

NEC 590.6(A)(3) requires that all 125-volt and 125/250-volt, singlephase, 15-, 20-, and 30-ampere receptacle outlets used on a construction site that are a part of a portable generator rated 15 kW or less have listed (Select the correct answer.) a. ground-fault circuit interrupter protection for personnel. b. grounding-type receptacles. c. locking-type receptacles.

Answer: a. Ground-fault circuit interrupter protection for personnel

Solution and Answer Guide SIMMONS/VIGSTOL, ELECTRICAL W IRING RESIDENTIAL, 21E, ©2024, 9780357766972; CHAPTER 33: RESIDENTIAL UTILITY-INTERACTIVE PHOTOVOLTAIC S YSTEMS TABLE OF CONTENTS Review .......................................................................................................................... 10

REVIEW Note: Refer to the National Electrical Code when necessary. Where applicable, responses should be written in complete sentences.

758.

Article _________________ of the National Electrical Code contains most of the requirements for installation of photovoltaic systems.

Answer: Article 690 759.

NEC Chapters _________________ through _________________ apply to PV installations except as modified by Article _________________.

Answer: Chapters 1 through 4; Article 690 760.

Name four electrical hazards associated with photovoltaic systems:

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: 

Exposed conductors



Voltage up to 600 volts dc



Continuous currents



Low-fault currents

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

761.

Name five components of a utility-interactive photovoltaic system:

________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ ________________________________________________________________ ____________ Answer: 

Modules



Mounting racks



Combiner/transition boxes



Disconnects



Inverters

762.

Which conductor types are permitted to be installed exposed for array circuits? ________________________________________________________________ ____________ Answer: USE-2 and PV are conductor types permitted to be installed exposed for array circuits.

763.

To size conductors and overcurrent devices for source circuits, you must multiply the module string short-circuit current by ________________________________________.

Answer: 125% per NEC 690.8(A)(1) 764.

When is a metallic raceway required for photovoltaic source circuits?

________________________________________________________________ ____________ Answer: A metallic raceway (or Type MC cable that complies with NEC 250.118(10) or metal enclosures such as boxes) is required for photovoltaic

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Solution and Answer Guide: Simmons/Vigstol, Electrical Wiring Residential, 21E, ©2024, 9780357766972, Chapter 1: General Information for Electrical Installations

source circuits when the circuits enter the building before the disconnecting means. See NEC 690.31(D).

765.

Photovoltaic modules that also serve as an outer protective finish for a building are known as ________________________________________________________________ __.

Answer: Building integrated photovoltaic systems 766.

Grounding electrode system requirements for a utility-interactive photovoltaic system are found in Section ____________________________ of the NEC. Answer: NEC 690.47 767.

The two methods permitted for connection of a photovoltaic system to a premises wiring system are either a ______________ or ______________ connection with respect to the service disconnecting means.

Answer: Supply side; load side

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