Glossary

ABYC—American Boat & Yacht Council, Inc. The preeminent standard-making organization for the recreational boating industry. The ABYC’s

Standards and Technical Information Reports for

Small Craft covers all areas of small-boat construction and repair, not just electrical matters. alternating current (AC)—Current that reverses direction. In the United States, the current reverses direction at the rate of 60 times per second, at 60 cycles, or 60 Hz. In Europe and other parts of the world, the standard is 50 Hz. See also direct current (DC); frequency; Hertz (Hz). alternator—A machine that uses the principle of magnetic induction to produce electricity. Alternators produce AC, which must be rectified to

DC to recharge onboard batteries. ammeter—A meter used to measure the current flowing through a circuit. Conventional meters must be hooked up in series with the circuit.

Modern inductive-style meters simply clamp around a wire in the circuit. ampacity—The amount of amperage an electrical conductor or device can safely conduct. ampere—The unit of measure for electrical current, or rate of electrical flow past a point in a circuit.

One ampere is equal to one coulomb (6.24 10 to the 18th power) of electrons passing a given point per second. Amperage is the stuff that trips circuit breakers and fuses, and, if not controlled, can burn up your boat! amp-hour—A current of one amp flowing for one hour; a measure of the electrical energy stored in a battery. anode—The more positively charged electrode in an electrical cell. average-responding multimeter—A meter whose voltage and amperage readings are calculated with an averaging formula. battery—Anelectrochemicaldevicethatproduces voltage,oravoltagedifferentialacrossitsterminals. battery bank—A group of two or more batteries linked together electrically. battery combiner—Electronic, voltage-sensitive switching device for automatically combining and separating batteries. battery isolation switch—A mechanical switch used to connect single or multiple batteries in parallel to a load. battery isolator—An electronic device that uses heavy-duty diodes to block electrical flow in one direction, effectively keeping batteries that are combined separated from each other electrically to prevent the discharge of one into the other. battery reserve capacity—The number of minutes a new, fully charged battery at 80°F (26.7°C) can be discharged at 25 amperes and maintain a voltage of 1.75 volts or more per cell (10.5 volts for a 12-volt battery). blade-type (ATO) fuse—Common fuse type using a colored plastic case for the fuse element; widely used in automotive applications today. branch circuit—A subcircuit fed from a main or primary circuit. bus bar—Metal bar used as a termination point for multiple conductors and circuits. A common point for either grounding or positive power feed. bus (AGC) fuse—The traditional glass cylinder style of fuse. cable—Wiring of any type; also cabling. capacitive-discharge ignition (CDI) unit—The

“brain” of a CD ignition system. capacitor—An electronic component that stores an electrical charge when voltage is applied.

carbon tracking—The carbon path etched into plastic or other insulating material by high voltage. cathode—The negatively charged electrode of a cell.

See also anode. cell—The smallest unit of a battery. A 12-volt storage battery has six cells. charge coils—Coils within a CD ignition system used to step up voltage supplied to the ignition coils. chassis ground—The case ground for metallic-cased electrical equipment. circuit—A complete path for electrical flow from the positive power source or terminal to the negative or ground terminal. A complete circuit has the following key elements: a power source, circuit protection (most circuits), a switch, an electrical conductor, a load or an appliance, and a return conductor to ground (negative). circuit breaker—An automatic switch that “trips” when the rated current flow through it is exceeded. A bimetallic circuit breaker uses the differential thermal expansion of dissimilar metals to open the switch. circular mils (CM)—Cross-sectional area of a conductor. closed circuit—A complete circuit, one that is turned on. coaxial cable—Used typically for antenna leads and to interconnect marine electronic equipment.

This two-conductor cable consists of an inner conductor insulated by a dielectric shield that is surrounded by a braided wire conductor and then insulated on the outside by another layer of nonconductive sheathing. cold-cranking amps (CCA)—Thenumberofamps abatteryat0°F( 17.8°C)candeliverfor30secondsandmaintainavoltageof1.2voltspercellor more. color coding—One of several acceptable methods of identifying wiring in circuits. conductor—Any material that has a minimal amount of resistance to electrical flow through it. conduit—A pipe in which electrical wiring is routed. continuity—A complete path or circuit that will allow electrical current flow. continuous rating—Rated for continuous exposure as compared to intermittent exposure. corrosion—The process by which metals are destroyed. See also galvanic corrosion; stray-current corrosion. crimp—(n.) A type of connector used for terminating wire. As in captive, ring-eye, etc. (v.) To attach a crimp-type connector to a wire using an appropriate crimping tool. cross-induction—The inducement of electron flow in a conductor from the magnetic field surrounding a nearby current-carrying conductor. CRT—Cathode ray tube. Televisions and computers—before they went to flat screens—used to have CRTs. current—The movement of electrons through a material. cycles—In AC, the current shift from + to – and back to + is one cycle. DC ground conductor—A normally currentcarrying conductor connected to the side of the power source that is intentionally maintained at boat ground potential. DC grounding conductor—A normally noncurrent-carrying conductor used to connect metallic non-current-carrying parts of directcurrent devices to the engine negative terminal, or a bus attached directly to it. Its purpose is to help minimize what is known as stray-current corrosion and is also sometimes connected into a lightning protection system as well. This wiring, which is generally covered with green insulation and connects to things like seacocks and propeller-shaft struts, should never be used as a

DC ground return for an electrical appliance.

deep-cycle battery—A battery designed to withstand being deeply discharged at a moderate rate of current draw over an extended period. de-rating—Reduction of a nominal rating, typically used with ampacity and voltage drop tables. Deutsch plug—Trade name for a high-quality waterproof plug assembly. DGPS—Differential global positioning system using both satellite and land-transmitted data to calculate position. dielectric—An insulating material. diode—An electrical semiconductor that allows electrical flow through it in only one direction. direct current (DC)—Electrical current that flows in one direction. See also alternating current (AC). double-pole—A classification of switch or circuit breaker that allows for the opening of two separate connections simultaneously. dry-cell battery—A battery using a dry, paste-like electrolyte instead of a liquid. See also wet-cell battery. DVOM—Common acronym for digital volt-ohm meter, also known as a multimeter or VOM. earth ground—A point that is at the same voltage potential as the local earth. electrical potential—Voltage. electrolyte—The solution inside a battery, but can be any electrically conductive fluid, such as salt water. engine negative terminal—A bolt or stud on an engine where the negative battery cable is connected. ferro-resonant charger—Simple unit using a ferroresonant transformer to convert AC to a lower voltage before being converted to DC for charging batteries. field winding—The wire coils wound onto the rotor inside an alternator. When electrical current flows through these windings an electromagnetic field is created around the rotor assembly, which

induces current flow in the alternator’s stator windings as the rotor spins. float charge—The third and final phase of battery charging. Also known as the finish stage. flywheel—A wheel used to maintain an engine’s rolling inertia between firing strokes. frequency—The number of complete alternations per second of alternating current. fuse—A conductive device designed to melt when amperage flow through it exceeds a rated amount. galvanic corrosion—Corrosion resulting from dissimilar, electrically connected metals being immersed in an electrolyte. galvanicisolator—Adeviceinstalledinserieswith thegreengroundingconductoroftheACshorepowercabledesignedtoblockgalvanicDCcurrent flowbutpermitthepassageofACifrequired. galvanicpotential—Areferencetowhereagiven metalmayfallonagalvanicseriesofmetalstable.

“Anodes”and“zincs,”astheyarecommonly called,haveahighergalvanicpotentialthan

Monel,stainlesssteel,andbronze. gangplug—Plugassemblyusedforconnectingmultiple conductors. gapping—Adjustingtheairgapbetweentwoelectrodes. gel-cellbattery—Typeofbatterywiththeactive electrolytecontainedinagelatinousmedium. generator—Generally,amachinethatproduces electricity. GPS—Globalpositioningsystem. ground—AtthepotentialoftheEarth’ssurface.A surfaceormassattheelectricalpotentialofthe

Earth’ssurface,establishedatthispotentialby anelectricallyconductingconnection,eitherintentionaloraccidental,withtheEarth,including anymetalareathatformspartofthewettedsurfaceoftheboat’shull.

ground-fault circuit interrupter (GFCI)—Adevice intendedtoprotectpeoplethatfunctionstodeenergizeacircuitoraportionofacircuitwhena currenttogroundexceedsapredeterminedvalue (5 milliamps in the U.S.). harness—A group of conductors running together. heat-shrink tubing—Insulating sheath that shrinks to size when heated. heat sink—A mounting for an electronic component designed to dissipate heat generated by the component to the surrounding air. Hertz (Hz)—The unit of frequency of an alternating current. One Hertz is equivalent to one cycle per second. horsepower—A measure of power. One horsepower is equivalent to 746 watts. hot—Generally considered the power feed conductor in electrical circuitry. house battery—Used to supply DC loads other than the engine stater motor. hydrometer—A float-type device used to measure the specific gravity of a fluid relative to another.

In electrical work, the battery hydrometer is used to measure the specific gravity of the battery electrolyte relative to pure water. ignition protected—A critical designation for any electrical device that is to be used in an area where gasoline, battery, or CNG or LPG vapors may accumulate. The ABYC describes ignition protection as: “the design and construction of a device such that under design operating conditions: it will not ignite a flammable hydrocarbon mixture surrounding the device when an ignition source causes an internal explosion, or it is capable of releasing sufficient electrical or thermal energy to ignite a hydrocarbon mixture, or the source of the ignition is hermetically sealed.” It is important to note that unlike most of the ABYC standards, ignition-protection requirements are also mandated by USCG regulations, and compliance is not voluntary, but mandatory. impedance—A form of resistance, the ratio of voltage to current. inductance—See cross-induction. induction—See cross-induction. inductive pickup—Used with measuring instruments to sense electrical current flow through wires. in-line (fuses, etc.)—A series connection. insulator—Material with a high electrical resistance. intercircuit short—Anywhere two circuits inadvertently become connected. intermittent rating—See continuous rating. internal short—Short circuit within the case of an electrical appliance. inverter—A device that converts DC voltage to AC voltage. joule—A measurement of energy. One Joule equals one watt for one second. jumpers—Short lengths of conductors, either wire or strapping. key—To activate. kilo (k)—A common prefix meaning 10 to the third power, or 1,000. lead—A length of wire, usually fairly short. As in

“meter lead.” lead-acid battery—Typical battery using lead plates and sulfuric acid electrolyte. LED outlet tester—Tester used to verify AC plug outlet wiring connection status that uses lightemitting diodes (LEDs) to signal status of connections at the outlet and its connected wiring. life cycles—The estimated number of times a battery can be discharged to a specified level and brought back up to full charge before it fails. live—Meaning power is available. load—Any device in a circuit that dissipates power. lugs—Ashort,threadedstudusedforwiretermination.

magnetic circuit breaker—Breaker that uses the magnetic field generated by a current-carrying coil to open the circuit. magnetic field—Magnetic lines of flux, invisible but present around all conductors with electrical current flowing through them. The magnetic lines of flux surrounding the Earth are the basis for the function of a magnetic compass. magnetic separation—Insulating or moving away from excessive magnetism. mega (M)—Prefix meaning 10 to the sixth power, or one million. micro ( )—Prefix meaning 10 to the minus sixth power, or one millionth. milli (m)—Prefix meaning 10 to the minus third power, or one thousandth. As in milliamp or millivolt. multimeter—Electrical meter with multiple functionality. ohm ( )—The unit of measurement of electrical resistance. ohmmeter—Adevicethatmeasureselectricalresistance. Ohm’s law—The mathematical equation that explains the relationship between volts, amps, and ohms. open—See open circuit. overcharging—Forcing excessive current into a battery. Overcharging causes excessive battery gassing and loss of electrolyte, a dangerous situation in either event. open circuit—A break in a circuit that interrupts the flow of current. open-circuit voltage—The voltage reading across the terminals of a battery at rest, with no charge going in and nothing drawing power from it. overcurrent-protection device—A fuse, circuit breaker, or other device installed in a circuit and intended to interrupt the circuit when the current flow exceeds design ratings. overrating—Applying more voltage or amperage to a device or component than it was designed to take. panelboard—Electrical distribution panel. Includes branch circuit breakers or fuses, and both negative and positive bus bars. May also contain system volt and amp meters and in the case of AC panels, a reverse-polarity indicator. parallel circuit—A circuit that allows more than one path for current to flow. pie formula—P I =E, or W =V A pinging—Knocking noise from engine that sounds like marbles are bouncing inside. polarity—The distinction between + and – in a circuit or on a load device. potential—See electrical potential. power—The rate at which energy is used or converted. The unit of measurement is the watt, which equals amperage times the voltage. One horsepower equals 746 watts. See also horsepower. pulsar coils—See trigger coils. radome—See scanner. reference voltage—The open-circuit voltage of a power source. relay—An electromechanical switch. See also solenoid. reserve capacity—The time in minutes that a battery can deliver 25 amps before dying. resistance—Measured in ohms. The opposition to electrical current flow (amps). reverse polarity—Connecting battery cables backwards. Or, in AC, the reversal of the black and white conductors. RFI—Radio frequency interference, emitted by electrical devices. Can produce radio “noise,” and can cause navigation equipment to malfunction. ripple voltage—Small amount of AC voltage that typically leaks past rectifiers inside alternators.

root-mean-square (RMS) multimeter—One using peak AC voltage values to calculate its readings. rotor—The moving component inside an alternator that has the field winding wrapped around it. rpm—Revolutions per minute. scanner—Moving radar antenna (rotating). self-discharge—The gradual loss of a battery’s capacity as it sits in storage. self-limiting—An electrical power source whose maximum output is restricted by its magnetic and electrical characteristics. self-scaling (auto-ranging) ammeter—A meter that automatically selects its best range for a measurement. series circuit—A circuit having only one path for current to flow through. series-parallel circuit—A circuit combining elements of both a series and parallel circuit. sheath—A material used as an insulating protective cover for electrical wiring. shore power—Power delivered from the dock. short circuit—A circuit fault that effectively shortens the designed path of current flow through a circuit. Short circuits usually eliminate the load from the circuit, allowing excessive current to flow. shunt—A short electrical bypass, generally associated with an ammeter. single loads—An individual electrical load in a circuit, as compared to multiple loads supplied by a circuit. sine wave—The waveform made when alternating current is charted over time. slave relay—See solenoid. slow-blow (MDL) fuse—A fuse with a delayed action used in motor circuits and other circuits where start-up load is significantly greater than the continuous current draw on the circuit. smart charger—Computerized multistage battery charger. socket—The female part of a plug and socket connector. solenoid—An extra-heavy-duty relay. Used for switching high-current-draw circuits such as starter-motor circuits. specific gravity—The density of a fluid. In electrical terms, the density of battery electrolyte as compared to pure water. Indicates state of charge in a battery cell. spike—Sudden surge in voltage. starting battery—Cranking battery capable of delivering high amperage for brief periods. static charge—Surface charge on a battery. High voltage but no amperage to back it up. stator—The stationary armature on an alternator that the rotor spins inside of, where alternator current is produced. stray-current corrosion—Corrosive activity induced by electrical leakage. See corrosion. sulfation—The normal chemical transformation of battery plates when a battery discharges. If left unattended, the sulfate turns to a crystalline substance and attaches itself permanently to the battery plates, ultimately ruining the battery as less and less plate area is exposed to the surrounding electrolyte solution. surface charge—See static charge. surge (spike)—See spike. switch—A device used to open and close a circuit. tachometer—Revolution counter. terminal—A point of connection to any electrical device. As in battery clamp, ring eye connector, etc. tilt switch—Mercury switch designed to turn off the starting circuit on an outboard engine when it’s tilted up out of the water. timing—Engine’s ignition timing. Point at which the spark plug fires in a cylinder. transducer—Two-way sender-receiver used with depth-sounder.

transformer—An electrical device consisting of two or more coils used to magnetically couple one circuit or section of a circuit to another. Transformers come in three basic configurations: one-to-one, where voltage on both sides of the transformer (primary and secondary) stays the same; step-up, where the voltage is increased from the primary to the secondary side of the unit; and step-down, where the opposite occurs. trigger coils—Used to send an electrical charge to a

CDI’s control box to tell it which cylinder to fire next. trim gauge—Used to indicate relative IO drive or outboard engine trim angle. trip (breaker)—To open the circuit. trip-free circuit breaker—A breaker designed in such a way that the resetting means cannot be manually held in to override the currentinterrupting mechanism. underrating—Not having adequate ampacity. See also ampacity. ungrounded conductor—A current-carrying conductor that is insulated from ground. Often thought of as the “hot” wire in a circuit. volt—The unit of voltage or potential difference from one side of a circuit to another. voltage drop—The loss of voltage as it works its way through a circuit. Excessive voltage drop indicates unwanted resistance in a circuit or circuit component. voltage regulation—Maintenance of voltage output despite variation in output current within engineered parameters. watt—A unit of power. The English unit of measurement is the horsepower, which equals 550 foot-pounds per second or 746 watts. waveform—Voltage as a function of time of a recurring signal. The waveform of AC voltage is the sinusoid, much like that of an ocean wave. wet-cell battery—A typical cranking or deep-cycle battery, as compared to a dry-cell flashlight battery. Wet-cell batteries can be recharged; most dry-cells cannot.