SOLUTIONS MANUAL for Electrical Wiring Industrial 18th Edition by Stephen Herman, Derrick Atkins

Electrical Wiring Industrial 18th Edition Stephen L. Herman, Derrick Atkins

CHAPTER 1 REVIEW

All answers should be written in complete sentences, and calculations should be shown in detail.

1.

In a set of construction drawings, where would an electrician find information about the location and placement of a building?

2.

From information on the composite site plan, where is the lowest area on the site and what is the elevation?

3.

What device is generally used to measure length on a plot or building plan?

4.

What would be the elevation, at the pole, of the bottom of a trench being dug to install telephone service using rigid nonmetallic conduit?

5.

Which of the methods for measuring ground resistance is used to measure resistance over a wide area?

6.

What is the difference, in SI units, between the lowest and the highest contours?

To answer the following questions, examine the composite site plan, the north and west elevations, the site plan symbols, and the NEC. 7.

What is the elevation of the manhole rim where the benchmark is established?

8.

What is the elevation of the first floor of the industrial building?

9.

What is the vertical distance from the manhole rim to the first floor of the industrial building? (Measure in decimal feet.)

10.

What is the vertical distance from the manhole rim to the first floor of the industrial building, measured in feet and inches accurate to 1⁄16 inch?

11.

Where is the preferred area for location of the construction trailer? Why did you choose that area?

12.

It was determined that the rigid nonmetallic conduit for the telephone service could be installed in a trench with a bottom elevation of 743.65 ft. If the conduit is allowed to rise a distance of 1 ft, how deep is the trench at the building?

13.

Refer to plan E1 on page 2 of the plans. What is the height of the boiler room floor?

14.

A cable containing two insulated conductors and a bare grounding wire is installed to a lighting standard mounted on a base similar to the one shown in Figure 1-22. Assume you are the electrician in charge. What instruction

would you give to a first-year apprentice who will make up the grounding connection?

15.

Why is it necessary to have a good grounding system for the building?

16.

What are the three most common methods of determining ground resistance?

17.

Explain the difference between a soft metric conversion and a hard metric conversion.

CHAPTER 2 REVIEW All answers should be written in complete sentences, and calculations should be shown in detail.

1.

What is the available fault current on the secondary of a three-phase, 225-kVA, 480//208/120-volt transformer with an impedance of 1.8%?

2.

What is the maximum standard size fuse permitted for a single-phase 25-kVA transformer with an impedance of 4%, installed in any location, with a primary voltage of 4160 V?

3.

Explain the operation of ground detectors and identify the situation that would require their use.

4.

Explain the reasoning for installation of the two meters.

5.

Two current coils are installed. What is their function and why was it not necessary to install three coils?

6.

If the secondary is ungrounded (such as that shown in Figure 2-11), what connections would likely be made to the grounding bus?

7.

If the secondary is grounded, what connection(s), in addition to those listed in problem 6, would be made to the grounding bus?

8.

What type of three-phase connection requires only two transformers?

9.

An installation requires a capacity of 86 kVA. The utility company intends to set two transformers as an open delta to supply this installation. What is the minimum kVA capacity of each transformer?

10.

Why do most three-phase transformer connections have at least one side (primary or secondary) connected in delta?

11.

What type of three-phase connection requires overcurrent protection in only two of the three phases?

Instructor Manual: Herman, Electrical Wiring Industrial 2024, Core ISBN; Chapter 1: Plans and Sitework

Instructor Manual Herman, Electrical Wiring Industrial 2024, Core ISBN; Chapter 1: Plans and Sitework

TABLE OF CONTENTS Purpose and Perspective of the Chapter ............................................................................................ 52 Chapter Objectives ........................................................................................................................... 52 What's New in This Chapter .............................................................................................................. 52 Chapter Outline................................................................................................................................ 52 Answers to EOC Review Questions .................................................................................................... 55

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51

Instructor Manual: Herman, Electrical Wiring Industrial 2024, Core ISBN; Chapter 1: Plans and Sitework

Purpose and Perspective of the Chapter The purpose of this chapter is to understand the information that is provided on construction plans. Construction plans have many symbols, legends, and scaling that the electrician must understand, and explanation is provided. Discussion of the requirements of the sitework is covered such as grounding and bonding and testing of the resistance of ground. With the initial site work, the electrician will install underground wiring methods and the requirements are covered.

Lastly, site drawings and the NEC will use Metric, English, and Trade Sizes for measurements and this chapter covers the usage and conversion of all three types of measurements.

Chapter Objectives After studying this chapter, the student should be able to 01.01 read site plans to determine the location of the specific items.

01.02 identify underground wiring methods.

01.03 perform International System of Units (SI) to English and English to SI conversions.

01.04 calculate metric measurements.

01.05 make measurements using a set of plans and a scale.

01.06 discuss different methods for determining ground resistance.

01.07 discuss the proper grounding of lighting standards and services.

What's New in This Chapter The following elements are improvements in this chapter from the previous edition: • NEC content is updated to the 2023 Code • Clarification on performance of grounding and bonding • Clarification on differences of grounding and bonding • Clarification on NEC Cover Requirements of wiring methods [return to top]

Chapter Outline The following outline organizes activities (including any existing discussion questions in PowerPoints or other supplements) and assessments by chapter (and therefore by topic), so that you can see how all the content relates to the topics covered in the text.

I. Construction Plans Topic (Slide 3) a. Contractor and Electrician need to inspect site plans b. Need to determine building locations c. Need to locate underground raceways, enclosures d. Need to locate staging areas such as trailers for material, tools, break areas II. Building Location (Slide 4) a. Reference to existing points such as centerline of a street b. Property lines and centerlines can locate the building and other site improvements

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Instructor Manual: Herman, Electrical Wiring Industrial 2024, Core ISBN; Chapter 1: Plans and Sitework

III.

IV.

V.

VI.

VII.

VIII.

IX. X.

XI. XII.

XIII.

c. Surveyors typically —stake out‖ the construction site and not the electrician Explanation of Plan Symbols (Slide 5) a. Discuss common symbols b. Compare and lookup symbols on the blueprints c. Activity: look at the symbols on the blueprints Contour Lines (Slide 6) a. Indicates existing and new grade levels b. Trenches need to have enough depth for cover requirements based upon grade level as determined by contour lines c. Ditch work is determined by the contract Benchmark (BM) (Slide 7) a. Reference point for all elevations b. Established by the surveyors c. Related to a city datum or mean sea level value for the site d. Activity: Locate the BM on the blueprints Elevations (Slide 8) a. Need to pay attention to the elevations of the building b. Plans provide need information on the building construction c. Elevation measurements can be plus or minus from the BM Invert Elevation (Slide 9) a. Level of lower edge of inside conduit entering a manhole b. Conduit is usually lower in installation Site Plan Scales (Slide 10) a. Scale used to take measurements on building plans b. Architectural scale uses fractions ¼‖ = 1’ c. Engineering scale uses factors of 10; 1‖ = 10’ d. Activity: determine the different scales used on the blueprints Traditional Scale (Slide 11) a. Discuss the various scales Reading the Scale (Slides 12 and 13) a. An example of a 1‖ = 10’ scale b. An example of a 1‖ = 50’ scale c. Activity: read some measurements on the blueprints Roller scale as typically used by estimators (Slide 14) Sitework (Slide 15) a. Need to review plans and specifications b. Be aware of all requirements c. Installations should be properly planned and times should not conflict with other trades Testing the site for grounding requirements (Slide 16) a. Proper grounding is essential for transient currents, electrical noise, lightning strikes to limit voltage spikes b. Effectiveness depends on resistivity of the Earth

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Instructor Manual: Herman, Electrical Wiring Industrial 2024, Core ISBN; Chapter 1: Plans and Sitework duplicated, or posted to a publicly accessible website, in whole or in

Instructor Manual: Herman, Electrical Wiring Industrial 2024, Core ISBN; Chapter 1: Plans and Sitework

XIV.

XV.

XVI.

XVII.

XVIII.

XIX.

XX.

XXI.

XXII.

c. Resistivity varies even within small areas due to soil types, moisture levels, electrolyte content, and temperature Testing (slides 17 and 18) a. Ground resistance testers b. Three main types I. Wenner four point II. Three-point fall-of-potential III. Clamp-on ground rod tester Wenner four point method (Slide 19) a. Uses four probes b. Uses a voltage and current measurement c. Activity: Research on the internet, cost and manufactures Three-point fall-of-potential test (Slide 20) a. Uses three probes b. Uses a voltage and current measurement c. Activity: Research on the internet, cost and manufactures The Clamp-on ground resistance test (Slide 21) a. Uses a clamp on style meter b. Utilizes a voltage and current measurement c. Activity: Research on the internet, cost and manufactures Grounding and bonding considerations (Slides 22 and 23) a. Establishes a common reference and connection to ground b. Reference for electrical systems and equipment c. Connects to earth to maintain at earth potential, zero volts, to eliminate shock hazards and prevent overvoltages which can damage insulation d. High frequency circuits grounded with large surface conductors due to skin effect Safety (Slide 24) a. Grounding and bonding conductors provide low-impedance connection to ground b. Also provided low-impedance fault current paths back to the source Bonding (Slides 25 and 26) a. Connects metal parts together b. Provides low-impedance fault current paths c. Allows high fault currents to facilitate operation of overcurrent protective devices d. Slide 26 displays the relevant grounding and bonding conductors Interpreting Site Plans (Slide 27) a. Textbook convention for plan Z1 b. Section of elevation to be changed, indicated with hash mark c. New elevations shown with dark heavy lines d. Activity: refer to blueprints Telephone Service (Slide 28)

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Instructor Manual: Herman, Electrical Wiring Industrial 2024, Core ISBN; Chapter 1: Plans and Sitework

XXIII.

XXIV.

XXV. XXVI.

XXVII.

XXVIII.

XXIX.

a. Discuss the drawing on the slide Direct burial wiring (Slide 29) a. Note the cover requirement of measurement is to the top of the wiring method b. Activity: Refer to NEC Table 300.5 for various cover requirements Underground Raceways (use slides 30 and 31) a. Refer to NEC 300.5 and 300.6 for requirements b. Refer to Article 344 and 352 for common raceways used for direct burial Manholes, discuss the picture in the slide (Slide 32) Lighting Standards, discuss the picture (Slide 33) a. Note the anchor bolts b. Note the conduits for the supply to the lighting standard c. Note the installation of the grounding electrode Metrics (SI) and the NEC (use slides 34 and 35) a. Discuss common conversions b. Cover soft and hard conversions and refer to NEC 90.9 c. Activity: Perform some common conversions such as meters to feet Trade Sizes (Slide 36) a. Discuss the Table b. Discuss the difference between actual size and Nominal Trade Values Guide to Metric Usage, discuss the prefixes (Slide 37)

[return to top]

Answers to EOC Review Questions 1. To find information about the location and placement of a building, the electrician should examine the site plans.

2. The southeast comer of the site is the lowest area, with an elevation of 745 ft.

3. A device called a scale is generally used to make measurements of building plans such as an architect or engineer scale. For example, the footprint is measured as 5.3 in. long. The scale is 50 ft per in.; thus, the length of the building is 5.3 in.  50 ft/ in. = 2.65 ft. In metric terms, the scale would remain unchanged; i.e., 600:1. The footprint would measure 5.3 in.  25.4 mm/in. = 134.6 mm. The actual length would be 134.6 mm  600 = 80,760 mm. Checking the accuracy by converting to feet, 80,760 mm/304.8 ft/mm = 265 ft.

4. The original surface at the location of the telephone service pole can be assumed to be at an elevation of 745.4 ft. The surface rise between the two contours (745 and 746) is 1 ft in a distance of 100 ft (2 in. on the plans). The pole is approximately four-tenths of the distance from the south contour; thus, the surface would rise 0.4 ft. The top of the pipe must be

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Instructor Manual: Herman, Electrical Wiring Industrial 2024, Core ISBN; Chapter 1: Plans and Sitework

at least 18 in. (1.5 ft) (450 mm) below grade according to NEC Table 300.5. Adding a generous 3 in. (0.25 ft) (75 mm) for the size 2 conduit would give the minimum elevation for the bottom of the trench. At the pole, the elevation of the bottom of the trench should be: 745 ft + 0.4 ft – 1.5 ft – 0.25 ft = 743.65 ft or less.

5. The Wenner four-point test measures ground resistance over a wide area. It utilizes four ground rods driven in the earth equally spaced apart.

6. The lowest contour is 745 ft and the highest is 751 ft. The difference is 751 – 745 = 6 ft. In SI units this is 6 ft  0.3048 m/ft = 1.8288 m (1828.8 mm).

7. The elevation of the manhole rim is 745.68 ft, taken directly from plans, in the upper left comer (BM 745.68 MH RIM).

8. The elevation of the first floor of the industrial building is 751.5 ft, taken from north elevation, west elevation, or from under the building name in the center of the building.

9. The first floor of the industrial building is 5.82 ft (1.77 m) above the manhole rim (751.5 – 745.68 = 5.82 ft).

10.

The first floor of the industrial building is 5 ft 9 and 13/16 in. (1.773 m) above the manhole rim. From the previous question, the first floor is 5.82 ft above the bench mark (12 in. per ft  0.82 ft = 9.84 in. 16 segments/in.  0.84 in. = 13.44 segments or 13/16 in.).

11.

The preferred location would be along the east property line at the north end of the property. The original contours are to remain; thus no grading will take place. A trailer located there would not need to be relocated.

12.

If the conduit were to rise 1 ft from the pole, the bottom would be at 744.65 ft (743.65 ft + 1 ft = 744.65 ft).

13.

The height of the boiler room floor is 732.5 ft.

14.

A cable containing two insulated conductors and a bare grounding wire is installed to a lighting standard mounted on a base similar to the one shown in Figure 1-23. The grounding wire should be connected to all of the metal parts of the standard and its base, which includes connecting to the metal conduits, the anchor bolts, and the wire to the ground rod. If the standard base is metal, the bolts would not need to be individually connected.

(Note NEC 250.110.)

15.

Proper grounding helps protect against transient currents, electrical noise, and lightning strikes.

16.

The three most common methods for determining ground resistance are: (i) the Wenner four-point method; (ii) the three-point fall-of-potential test; and (iii) the clamp-on ground resistance test.

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Material Instructor Manual: Herman, Electrical Wiring Industrial, 18e, ISBN 9780357767245; Chapter 2: The Unit Substation

17.

Soft Metric Conversion: dimensions of a product already designed and manufactured to the English system have their dimensions converted to SI metric dimensions. The product does not change in size. Hard Metric Conversion: an existing product is redesigned into a new size. [return to top]

Instructor Manual Herman, Electrical Wiring Industrial, 18e, ISBN 9780357767245; Chapter 2: The Unit Substation

TABLE OF CONTENTS Purpose and Perspective of the Chapter ............................................................................................ 58 Chapter Objectives ........................................................................................................................... 58 What's New in This Chapter .............................................................................................................. 58 Chapter Outline................................................................................................................................ 58 Answers to EOC Review Questions .................................................................................................... 61

© 2024 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in

57