Electrical and Lighting Glossary

A-Line Lamp: An incandescent lamp generally used in most indoor residential homes.
Accent Lighting: Lighting used to accent or highlight a particular object and is four or five times the level of ambient light in an area.
Alternating Current (AC) : An electric current that changes direction with regular frequency.
Alternator: An electric generator that produces alternating current.
Ambient Lighting: Light that illuminates a space.
American Wire Gauge (AWG) : A standard measure representing the size of a wire (a larger number represents a smaller wire).
Ampacity: The current a conductor can carry continuously.
Ampere: A type of electric current that is produced by one volt applied across one ohm.
Analog: A unit of measure that utilizes varying physical restrictions.
Arc Tube: A tube enclosed by a glass made of clear quartz that contains an arc stream.
Ballast: An electrical device used with fluorescent lamps to supply sufficient voltage to operate the lamp but also then limits the current during operation.
Ballast Cycling: An adverse condition where the ballast turns a lamp on and off due to overheating.
Battery: Two or more cells connected together to provide electrical current.
Blower Doors: Devices used to see how much air leaks through windows, doors, and other places in a house.
Branch Circuit: Conductors that protect circuits and outlets.
Brownout: A reduction in power when the demand for electricity exceeds its generating ability.
BTU (British Thermal Unit) : The standard unit for measuring heat quantities.
Cable Lighting System: A low voltage lighting system where electricity is conducted through cables.
Candlepower/Candela: Unit of light intensity in a specific direction, measured in "Candelas."
Capacitor: A device that stores electrical charge.
Cathode: An electrode that emits electrons.
Cell: A device that converts chemical energy into electrical current in a battery.
Circuit Breaker: A device designed to open and close a circuit without causing damage to itself.
Circuit Extensions: Items used to extend or add on to an existing circuit to provide an additional power source.
Code Corrections: Procedures used to correct wiring that does not meet proper safety conditions.
Colored Glass Filter: Glass formed with the color in the glass as opposed being coated on the surface.
Color Temperature: A measure of the color appearance of a light source often described with terms such as "warm" (orange) or "cool" (white).
Compact Fluorescent Lamp (CFL) : A family of small fluorescent lamps made with a glass tube design and high color illumination.
Constant Wattage (CW) Ballast: A HID ballast where primary and secondary coils are isolated.
Continuous Load: A load who?s maximum current is expected to continue for 3 hours or more.
Contrast: The relationship between the illumination of an object and its background.
Controller: A device that serves to regulate the electric power delivered to a connected apparatus.
Cornice Lighting: Light sources shielded by a panel parallel to the wall and attached to the ceiling.
Cove Lighting: Light sources shielded by a recess and distribute light over the ceiling.
Current: The flow of electricity measured in amperes.
Cut-off Angle: The angle where a light fixture or other shielding device cuts off direct visibility of the lamp itself.
Daylight Compensation: An energy-saving dimming system that reduces lamp output when in the presence of natural light.
Diffuse: Dispersed light distribution that softens illumination.
Dimmer: A device used to vary the brightness of lamps.
Diode: An electronic semiconductor device that allows a current to flow in just one direction.
Direct Current (DC) : Circuit allowing electrons to flow in only one direction.
Downlight: A light fixture recessed into the ceiling and illuminates in a downward direction.
Efficacy: A measure used to compare light output to energy consumption.
Electroluminescent: A light source technology that provides long lamp life while still consuming very little energy.
Electric Resistance Heating: A type of heating system that generates heat by passing current through a conductor, often used in baseboard heating systems.
EMI: Electromagnetic Interference: High frequency interference caused by electronic components that interfere with the operation of electrical equipment.
Emergency Lighting: Lighting for when normal lighting fails.
Energy: The ability to do mechanical work; it is measured in kilowatt-hours.
Energy Efficiency Ratio (EER) : The ratio of the cooling capacity of the air conditioner to the total electrical input in watts.
Energy-saving Ballast: A magnetic ballast designed to operate more efficiently than "standard magnetic" ballasts.
Fault: A short circuit in an electrical system.
Filament: A tungsten wire that lights when electric current runs through it.
Flexible Track Lighting System: A low-voltage lighting system where the track holding the light fixture is able to bend.
Fluorescent Lamps: Devices that produce light by passing electricity through a gas.
Foot-Candle: The amount of light reaching an object.
Four-Way Switch: A wall switch allowing three switches to control one lighting system.
Frequency: The rate at which a current changes direction.
Generator: A rotating machine that converts mechanical energy into electrical energy.
Glare: A condition caused by light coming directly into the eye from a light source.
Grid: An electrical distribution network.
Ground: A connection between an electrical circuit and the earth.
Halogen Lamp: An incandescent lamp that contains halogen gases which slow the evaporation of the tungsten filament.
Hard Wired: A light fixture permanently connected to an electrical source with a cord.
Hertz (Hz) : The unit of frequency.
HID Lamp: High Intensity Discharge lamps have a longer life and tend to provide more light than most light sources.
High Bay: A type of lighting where the ceiling is 20 feet or higher.
High Output (HO) : A lamp or ballast designed to operate at higher currents in order to produce more lumens.
High-Tech Troubleshooting: A procedure used to identify any electrical problems.
Horsepower: A unit of power equal to 746 watts.
Hot Restart/Hot Restrike: The automatic restarting of a HID light source after a momentary loss in power.
Illuminance (Light Level) : The light incident on a surface.
Impulse: A current?s surge.
Incandescent Light Bulbs: Light bulbs that produce light by passing electricity through a thin filament.
Infrared Cameras: Cameras used to see any heat leaking out of a building.
Infrared Radiation: An invisible radiation where wavelengths are longer and lower than that of visible radiation.
Instant Start: Fluorescent lamps that start instantly without pre-heating their cathodes.
Insulation: Materials that have a high resistance to electrical currents.
Inverter: A device that converts direct current into alternating current.
Ion: A positively or negatively charged atom or molecule.
Joule: A unit of energy equal to one watt for one second.
Kilovolt (kV) : A unit of electrical potential equal to 1,000 volts.
Kilowatt (kW) : Real power delivered to a load.
Kilowatt-hour: A unit of energy equal to one kilowatt for one hour; the typical unit used to measure energy and for billing customers.
Layers: Layers of light in a given space that are created by several different kinds of lighting (a combination of task, general, ambient, and accent lighting systems, etc).
LED: Light Emitting Diode: a small, energy-efficient electronic light that has a very long life.
Light Loss Factor (LLF) : Factors that allow a lighting system to operate at less than initial conditions.
Light Trespass/Spill Light: Light emitted into an unintended area.
Life Cycle Cost: Total costs associated with purchasing and operating a system over its lifetime.
Limit Switch: A switch used to alter the electric circuit.
Liquid-Filled Transformer: A transformer immersed in a liquid that acts as both a cooling and insulating method.
Live Parts: Electric components that are uninsulated or exposed and are therefore hazardous.
Load: The amount of power supplied by an electrical device.
Loadbreak: Disconnecting a load without damage.
Load Center: The source for all power to a structure.
Load Curve: A way to plot the electronic demand versus time.
Load Factor: Measures how efficiently an electrical system?s capacity is utilized.
Load Switching: Transferring a load from one source to another.
Louver: A screen made of opaque material to minimize glare from a light source.
Low Voltage: A wiring system that provides power to an electronic device operating on a voltage level lower than the standard 110 volts.
Lumen: A unit of measure used to describe the amount of light a lamp emits.
Luminaire: A light fixture.
Mercury Vapor Lamp: A HID lamp where light is produced by radiation from mercury vapor.
Metal Enclosed/Metalclad: A device that is surrounded by a metal casing.
Metal Halide: A HID lamp where the light is produced by radiation of metal halide and mercury vapors.
Motors: Electronic device used to move, switch, or adjust one or more of the systems within a dwelling.
National Electrical Code (NEC) : A guideline used for safeguarding people/property from electrical hazards.
Neodymium: A silvery metal used to make purple glass for incandescent light bulbs, eye protection goggles, laser rods, filters, and lenses.
Occupancy Sensor: Control device that turns lights off after a space becomes unoccupied.
Ohm: The unit used for measuring resistance.
Opaque: A material that does not transmit visible light.
Optics: The components of a light fixture; the light emitting performance of a fixture.
Outlet: Where a current is taken to supply something outside the wiring system.
Overload: The excess of normal capacity that could cause damage due to overheating.
Overvoltage: A voltage that is above the normal rated voltage for a circuit.
PAR Lamp: A parabolic aluminized reflector lamp.
Pendant: Lamps equipped with shades to avoid glare that are suspended from the ceiling.
Phase: Classification of an AC circuit.
Photocell: A light-sensing device that controls light fixtures and dimmers in response to detected light levels.
Power: The rate at which energy is transferred.
Power Outage: An interruption in power.
Power Outlet: An assembly intended to distribute power to temporary equipment.
Preheat: A ballast that uses a starter to heat up a fluorescent lamp before high voltage starts it.
Puncture: A disruptive discharge that occurs in a solid dielectric.
Radio Frequency Interference (RFI) : Interference to a radio frequency band caused by other high frequency equipment in the area.
Rapid Start: A fluorescent system that does not require starters and emits light very quickly.
Rated Life: The time at which half of a certain kind of lamp will burn out.
Reactive Power: The product of voltage and current consumed by reactive loads.
Real (Active) Power: The rate at which energy is transferred, often measured in watts or kilowatts.
Receptacles: Power sources in a structure that provide electricity.
Reflector/Refractor: The device on a light fixture that shrouds the lamp and redirects the light emitted from it.
Regulation: The ballast?s ability to hold a constant output despite fluctuations in voltage.
Relay: A device that switches a load on or off due to small changes in its current.
Resistor: Anything that limits a current's flow.
Retrofit: Upgrading a preexisting fixture by installing new parts.
Sconce: A light fixture attached to a wall.
Semi-specular: Light reflection characteristics of a material.
Service: Equipment used for delivering electric energy from a utility to a wiring system.
Series Gap: Internal gap(s) where voltage is supposed to appear.
Series/Multiple: The winding of two coils that are connected for series/multiple operation.
Service Cable: Conductors transferred by cables.
Spacing Criterion: The maximum distance that interior fixtures may be spaced to ensure uniform illumination.
Specular: A mirrored or polished surface.
Starter: An electrical device used to start a fluorescent lamp.
Stroboscopic Effect: When rotating machinery appears to be standing still due to the alternating current supplied to multiple light sources.
Switchboard: A large assembly of panels mounted with protective devices.
Switches: Circuit interruption devices that control the flow of electricity in the home.
Symmetric: The normal flow of current.
Systems Capacity: A system that has met a customer's need.
Tap: A connection made from outside the wiring system.
Tandem Wiring: An option where a ballast is shared by two or more luminaries, thereby increasing efficiency.
Task Lighting: Lighting that is specifically installed to illuminate an area where tasks are performed.
Three-Way Switch: A wall switch allowing two switches to control one lighting system.
Track and Accent Lighting: A lighting system that provides variable degrees of light in multiple directions.
Transfer Switch: An electronic device that can disconnect from one power source in order to connect to another.
Transformer: A device wherein electromagnetic induction transfers electrical energy from one circuit to another.
Transient: A high amplitude, short duration pulse overlaid onto the normal voltage.
Translucent: A material through which some light is transmitted but causes some distortion.
Transparent: A material that transmits visible light with very little distortion.
Troffer: A recessed light fixture that uses fluorescent lamps and is installed flush with the ceiling.
Turn Ratio: The number of turns in a high voltage winding in relation to that of a low voltage winding.
UL: Underwriters Laboratories, Inc: a not-for-profit safety organization.
Uninterruptible Power Supply: A device that provides a constant output in spite of interruption.
Uplight: Light directed from a light fixture at or above 90 degrees.
UV Radiation: Light that is invisible to the eye.
Vandal-resistant: Fixtures with break-resistant shielding and tamper-proof screws.
Vapor-Tight Luminaire: A light fixture that doesn?t allow water vapor or gas to enter its enclosure.
VCP: Visual Comfort Probability: a rating system for evaluating direct glare.
Very High Output (VHO) : A fluorescent lamp operating at a very high current and therefore creating more light than a standard lamp.
Volt: An electrical flow that carries a current of one ampere.
Voltage Drop: The loss of voltage due to electrical resistance of a wire and its light fixture.
Wall Grazing: Dramatic light and shadow effects on a surface.
Wall Washing: A special lighting method that produces an even level of light on a wall in order to reduce the surface?s texture.
Watt: A unit of power equal to one ampere.
Wiring: A distribution network conducting electricity throughout a building.
Whole-House Fan: A fan used to ventilate an entire building.