Electrical Glossary

Electrical Glossary

    

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Electrical Glossary A
Amp – A measurement of the amount of electrical current flowing in a circuit at any moment.
Antioxidant – A paste applied to aluminum wires to inhibit corrosion and maintain safe connections.
Armored cable – Two or more insulated wires wrapped in a protective metal sheathing.

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Electrical Glossary B
Ballast – A transformer that regulates the voltage in a fluorescent lamp.
Battery backup – A device that provides a short duration of emergency power to connected equipment in the event of a power failure. This is intended to allow sufficient time to bring power back on line or to properly shut down equipment.
Bell wire – A thin, typically 18-gauge, wire used for doorbells.
Bi-pin base – A standard base used on many small incandescent light bulbs (especially halogen lamps), and on most fluorescent lights as well, where the filaments are involved in starting the tube when it is turned on.
Box – A metal or plastic enclosure within which electrical connections are made.
Building code – A set of rules that specify the minimum acceptable level of safety for constructed objects such as buildings and nonbuilding structures. The main purposes are to protect public health, safety and general welfare as they relate to the construction and occupancy of buildings and structures.
Bulb life – The average rated time period of the operation of a bulb before it fails to product light.
Bus bar – A main power terminal to which circuits are attached in a fuse or breaker box. One bus bar serves the circuit's hot side; the other, the neutral side. Some service panels and all subpanels have separate neutral and ground bus bars.
BX – Armored cable containing insulated wires but no ground wire.

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Electrical Glossary C
Cable – Two or more insulated wires wrapped in metal or plastic sheathing.
Cable f-connector tool – A specialized screwdriver used by telecommunications and network technicians to loosen/tighten f connectors on splitters and female f ports.
Candelabra bulb – Small-based incandescent light bulbs used in chandeliers and other lighting fixtures that provide decoration as well as illumination.
Carbon monoxide alarm – Detects the presence of carbon monoxide (CO) in the air. The CO alarm monitors the CO concentration in the surrounding environment over time.
Charge-coupled device (CCD) – An image sensor, common in surveillance cameras, which produces a high quality image with low noise.
Circuit – The path of electrical flow from a power source through an outlet and back to ground.
Circuit breaker – A switch that automatically interrupts electrical flow in a circuit in case of an overload or short.
Closed-circuit TV (CCTV) – System of transmitting a video signal through a closed network of surveillance cameras.
Color rendering index (CRI) – A measure of color accuracy. A lamp’s light spectrum may change the color appearance of objects.
Codes, electrical – Laws and regulations governing safe wiring practices.
Color temperature – The measurement of color expressed in Kelvin (K).
Combination arc fault circuit interrupter (CAFCI) – A circuit breaker that protects against hazardous electrical arcing caused by frayed wires, damaged insulation, etc. The 2008 National Electrical Code requires CAFCIs on all circuits that supply a dwelling unit living area.
Combination smoke alarm – Includes a smoke and a carbon monoxide (CO) alarm in one unit.
Common – A terminal on a three-way switch, usually with a dark-colored screw and marked COM.
Compact fluorescent light bulb (CFL) – A high efficiency fluorescent lamp type.
Conductor – A wire or anything else that carries electricity.
Conduit – Rigid (metal or PVC) or flexible tubing through which wires are run.
Continuity tester – An instrument that tells whether a device is capable of carrying electricity.
Cord reel – A device for winding a self-contained cord either manually or automatically.
Cord strap – A pliable, plastic strap with a carry handle that bends around a cord and self locks.
Cord winder – A portable device with a spool to manually wind a cord around for storage.
Cord wrap – A rigid plastic holder with a carry handle and cord end lock on which a cord is wrapped.
Cutting pliers – Pliers intended for cutting wire. They are generally not used to grab or turn anything.

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Electrical Glossary D
Device – A unit of an electrical system that carries or controls electric energy as its principle function.
Digital video monitoring system – System employing one or more surveillance cameras and a monitor for viewing. Typically, systems also employ a digital video recorder (DVR) for recording, playing back and archiving surveillance video.
Dimmable CFL – A high efficiency light bulb that can be dimmed using a matching dimming ballast and dimmer.
Dimmer – A rotary or sliding switch that lets you vary the intensity of a light.
Drywall saw – A saw with teeth used to cut drywall or ceiling tile.
Duplex receptacle – A device that includes two plug outlets. Most receptacles in homes are duplexes.

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Electrical Glossary E
Electrical metallic tubing (EMT) – Thin-walled, rigid conduit suitable for indoor use.
Electronic low frequency (ELV) bulbs – A lighting source that uses a solid-state electronic transformer to step down the incoming line voltage to the voltage required by the lamp (typically 12 V). Track lights are usually electronic low-voltage.
End-of-the-run – An adjective used to describe devices located at the end of a circuit. No wires continue from its box to other devices.
ENERGY STAR – A government-backed program helping businesses and individuals protect the environment through superior energy efficiency.
ETL mark – Proof of product compliance to North American safety standards.

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Electrical Glossary F
Feed wire – A wire that brings household current to a device.
Fishing – Pulling cables through finished walls and ceilings.
Fish tape – A hooked strip of spring steel used for fishing cables through walls and pulling wires through conduit.
Fixture – Any light or other electrical device permanently attached to a home's wiring.
Flexible metal conduit – Tubing that can be easily bent by hand.
Flood lights – Any directional lighting source that floods a wide area or wall surface with light.
Fluorescent tube – A light source that uses an ionization process to produce ultraviolet radiation, which becomes visible light when it hits the coated inner surface of the tube.
Four-way switch – A type of switch used to control a light from three or more locations.
Fuse – A safety device designed to stop electrical flow if a circuit shorts or is overloaded. Like a circuit breaker, a fuse protects against fire from overheated wiring.

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Electrical Glossary G
Ganging – Assembling two or more electrical components into a single unit. Boxes, switches and receptacles are often ganged.
Greenfield – Flexible metal conduit through which wires are pulled.
Ground – Refers to the fact that electricity always seeks the shortest path to the earth. Neutral wires carry electricity to ground in all circuits. An additional grounding wire, or the sheathing of metal-clad cable or conduit, protects against shock from a malfunctioning device.
Ground fault circuit interrupter (GFCI) outlet – A safety device that senses any shock hazard and shuts off a receptacle.
Ground fault circuit interrupter (GFCI) breaker – Circuit breaker that de-energizes a circuit or portion of a circuit within a set period of time when it is tripped by an overload of current, a short circuit or a line-to-ground fault, which occurs when an unwanted path forms between an electrical current and a grounded element.

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Electrical Glossary H
Heat alarm – A device that senses fire by air temperature, rather than particulate matter, which can help avoid false alarms in spaces where airborne contaminants may be a problem.
High-intensity discharge (HID) – A type of lighting, including lamps such as halogen, mercury vapor, metal halide and sodium. All HIDs produce a bright, economical light.
Hot wire – The conductor of current to a receptacle or other electrical device.

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Electrical Glossary I
Incandescent bulb – A light source with an electrically charged metal filament that burns at white heat.
Insulation – A nonconductive covering that protects wires and other electricity carriers.
Ionization smoke alarm – An alarm that sounds when electrically charged particles released during a fire interfere with the electrical current that flows through the alarm's detection chamber.

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Electrical Glossary J
Joule rating – A joule is a measurement of energy. The joule rating on a surge protector indicates the amount of energy that a device is capable of absorbing. In general, the higher the joule rating, the better the unit is able to protect your equipment and the longer it will last.
Jumbo wallplates – Wallplates approximately 3/4" higher and wider than standard plates and used to conceal greater wall irregularities than those hidden by midway wallplates.
Junction box – An enclosure used for splitting circuits into different branches. In a junction box, wires connect only to each other, never to a switch, receptacle or fixture.

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Electrical Glossary K
Kilowatt (kW) – One thousand watts. A kilowatt hour is the standard measure of electrical consumption.
Kilowatt hour – A unit of energy equivalent to one kilowatt of power expended for one hour of time.
Knockouts – Tabs that can be removed to make openings in a box for cable or conduit connectors.

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Electrical Glossary L
LB connector or fitting – An elbow for conduit with access for pulling wires. Connections cannot be made within this fitting.
Lead – A short wire coming from a fixture, typically stranded, to which a household wire is spliced. It is used instead of a terminal.
Light-emitting diode (LED) – A solid-state, long-lived light source that produces very little heat.
Light-emitting diode (LED) bulb – A collection of LEDs in a single housing, used as an alternative to an incandescent lamp.
Lineman's pliers – A type of plier designed to grip and cut standard electrical wire.
Long-nose pliers – A gripping and cutting plier for reaching into cavities where materials are unreachable by fingers or other means.
Lumens – A unit of measurement of light energy. Specifically, lumens measure the amount of light a lamp produces in all directions.
Lumens per watt – A unit of measurement of light energy that measures the efficiency of a light source. The higher the number, the more light is emitted.

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Electrical Glossary M
Magnetic low frequency (MLV) bulbs – A low-voltage incandescent lighting source that uses a magnetic transformer to step down the incoming line voltage to that required by the lamp (typically 12 V). Track and recessed lights can be magnetic low-voltage.
MC cable – Armored cable containing at least two insulated wires and an insulated ground wire.
Metal oxide varistor (MOV) – A component in surge protectors that absorbs excess electrical energy and clamps the voltage to a safe level.
Metal raceway – A decorative metal channel used to extend line voltage wiring for outlets, switches and fixtures across the surface of walls in dry/indoor locations.
Meter – A device that measures the amount of electrical energy consumed by a residence, business or an electrically-powered device.
Meter socket – The meter socket is the heart of all metering products. The most common meter socket consists of an assembly of matching jaws to accommodate the blades of a detachable watt-hour meter and a base for proper support and positioning of these jaws.
Middle-of-the-run – An adjective used to describe devices located between two other devices on a circuit. Wires continue from its box to other devices.
Midway wallplates – Wallplates that are approximately 3/8" higher and wider than the standard size that can be mounted onto larger volume outlet boxes and/or used to hide wall surface irregularities.
Multi-location dimmer – A dimmer that allows full-range dimming from all locations in three-way and four-way circuits.
Multitester – A device that measures voltage in a circuit and performs other tests.

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Electrical Glossary N
Neon tester – A voltage sensing device used to detect energized circuits or equipment.
Neutral wire – A conductor that carries current from an outlet back to ground, clad in white insulation.
New-work box – A metal or plastic box attached to framing members before the wall material is installed.
Nonmetallic raceway – A decorative plastic channel used to extend line voltage wiring across the surface of walls for outlets, switches and fixtures in dry/indoor locations.
Nonmetallic (NM) sheathed cable – Two or more insulated wires and a bare ground wire clad in a plastic covering.

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Electrical Glossary O
Old-work box – A metal or plastic box, sometimes called a remodel box, designed for a hole cut in drywall or plaster and lath.
Outlet – Any potential point of use in a circuit, including receptacles, switches and light fixtures.
Ohm – Measure of electrical resistance in a material.
Overload – A condition that exists when a circuit is carrying more amperage than it was designed to handle. Overloading causes wires to heat up, which in turn blows fuses or trips circuit breakers.

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Electrical Glossary P
Photoelectric smoke alarm – An alarm that sounds when smoke particles interfere with and reflect the alarm's light beam.
Pigtail – A length of wire, stripped at both ends, spliced with one or more other wires. It is used instead of attaching two or more wires to a terminal, an unsafe connection.
Plug-in dimmer – A dimmer that attaches to the plug of a table lamp or floor lamp. No installation is necessary.
Polarized plugs – Plugs designed so the hot and neutral sides of a circuit can't be accidentally reversed. One prong of the plug is a different shape than the other.
Power – The rate at which energy is converted.
Power inverter – An electrical device that converts direct current (DC) to alternating current (AC).
Punch-down tool – A hand tool used by telecommunications and network technicians to terminate cable runs and cross-connect jumpers.

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Electrical Glossary R
Raceway wiring – Surface-mounted channels for extending circuits.
Receptacle – An outlet that supplies power for lamps and other plug-in devices.
Recessed can light – A light fixture set into a wall cavity so the lens and trim are flush with the ceiling.
Remodel box – A metal or plastic box, sometimes called an old-work box, designed for a hole cut in drywall or plaster and lath.
Rigid conduit – Wire-carrying metal tubing that can be bent only with a special tool.
Rocker dimmer – A style of dimming control that coordinates with a standard paddle switch for lighting. The rocker switch is designed to turn the lights on and off while the dimming function enables the user to select a desired light level.
Romex – A trade name for nonmetallic sheathed cable.
Rotary dimmer – A style of dimming control in which a dial knob allows the user to adjust the lights to suit any activity.

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Electrical Glossary S
Scene selector dimmer – A style of dimming control where the lighting effect is achieved by adjusting one or more zones of lighting to the desired intensity.
Screwless wallplate – Wallplate that utilizes a subplate for mounting and does not require screws.
Service entrance – The point where power enters a home.
Service panel – The main fuse box or breaker box in a home.
Short circuit – A condition that occurs when hot and neutral wires contact each other. Fuses and circuit breakers protect against fire, which can result from a short.
Single-pole dimmer – A dimmer that controls a lighting circuit from one location only.
Slide dimmer – A style of dimming control in which a small slider allows the user to adjust the lights to suit any activity.
Spotlights – Directional lighting to emphasize an object or draw attention to specific features, areas or displays.
Standard wallplate – A plate designed to enclose an electrical box, with or without a device installed in the box.
Stripping – Removing insulation from wire or sheathing from cable.
Strut – A strut is a structural component designed to resist longitudinal compression. Struts provide outwards-facing support in their lengthwise direction, which can be used to keep two other components separate, performing the opposite function of a tie. They are commonly used in architecture and engineering.
Subpanel – A subsidiary fuse box or breaker box linked to a service panel that has no room for additional circuits.
Suppressed voltage rating – An Underwriters Laboritories rating for surge suppressors. The rating measures fire, electric shock and personal injury hazards, and categorizes devices by how much voltage they can clamp, a measure of how much voltage they prevent from passing through to electronic equipment.
Surge protector – A device inserted in an alternating current (AC) line and/or telephone line to prevent damage to electronic equipment from voltage spikes called transients.
System ground – A wire connecting a service panel to the earth. It may be attached to a main water pipe, to a rod driven into the ground or to a plate embedded along a footing.

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Electrical Glossary T
Tap dimmer – A style of dimming control with a flat button that, when pressed, allows lights to return to a desired preset level. In addition, a small slider adjusts lights to suit any activity.
Three-way dimmer – A dimmer that should be used when a lighting circuit is controlled from more than one location.
Three-way switch – Operates a light from two locations.
Time-delay fuse – A fuse that does not break the circuit during the momentary overload that can happen when an electric motor starts up. If the overload continues, the fuse blows, shutting off the circuit.
Toggle – A switch with a lever-type actuator that makes or breaks switch contact as its position is changed.
Toggle dimmer – A style of dimming control where a switch is used to turn the light on or off. In addition, a small slider allows the user to adjust the lights to suit any activity.
Torpedo level – A tool that indicates whether a surface is level or plumb.
Transformer – A device that reduces or increases voltage. In home wiring, transformers step down current for use with low-voltage equipment such as thermostats and doorbell systems.
Travelers – Two of the three conductors that run between switches in a three-way installation.

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Electrical Glossary U
Underwriters knot – A knot used as a strain relief for wires in a lamp socket.
Uninterruptible power supply (UPS) – Also called battery backup, it's a device that provides a short duration of emergency power to connected equipment when there is a power failure. This is intended to allow sufficient time to bring power back on line, or to properly shut down equipment.

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Electrical Glossary V
Volt – A measure of electrical pressure.
Voltage protection rating – A rating selected from a list of preferred values as given in Table 63.1 of ANSI/UL 1449 and assigned to each mode of protection.
Voltage tester – A piece of electronic test equipment used to determine the presence or absence of an electric voltage in a piece of equipment.

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Electrical Glossary W
Watt – A measure of the power an electrical device consumes. Watts = Volts x Amps.
Wire cutters – A hand tool that cuts any type of steel and non-ferrous wire, bar, spring, chain, ground and anchor rod, wire rope, fasteners, bolts and cable.
Wire/cable crimper – A hand tool designed to attach electrical connectors, lugs and terminals.
Wire/cable stripper – A hand tool designed for cutting and removing the outer layer of insulation found on wire or cable.
Wire nut – A screw-on device used to splice two or more wires.

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