Glossary of Lighting Terms

BALLAST:
A magnetic or electronic device used to control the starting and operation of discharge lamps. 2) an electrical device used with fluorescent or HID lamps to supply sufficient voltage to start and operate the lamp but then to limit the current during operation.

COMPACT FLUORESCENT LAMP (CFL):
A generic name used for a whole family of small, single-ended fluorescent lamps with a folded, bridged, or spiral glass tube design and with high color rendering and a long life (>8,000 hours) An alternative to incandescent lighting.

ENERGY:
A measure of work done by an electrical system over a given period of time, often expressed in kilowatt-hours (kWh).

FLUORESCENT LAMP:
A discharge lamp in which a phosphor coating transforms ultraviolet energy into visible light. 2) a low-pressure mercury electric-discharge lamp in which a phosphor coating on the inside of the glass tubing transforms some of the ultraviolet energy created inside the lamp into visible light.

FOOT-CANDLE:
A standard measurement of illuminance, representing the amount of illuminance on a surface one foot square on which there is a uniformly distributed flux of one lumen. 2) Foot-Candle: the amount of light reaching a subject.

HID LAMP:
Abbreviation for high intensity discharge. Generic term describing mercury vapor, metal halide and high pressure sodium lamps.

HIGH-BAY:
Pertains to the type of lighting in an industrial application where the ceiling is 20 ft. or higher. Also describes the application itself.

HIGH OUTPUT (HO) LAMP:
A lamp or ballast designed to operate at higher currents (800 mA) and produce more light.

INCANDESCENT LAMP:
Generally an inefficient lamp type in which light is produced by means of an element heated to the point of incandescence by the passage of an electric current.

INSTANT START:
Refers to fluorescent lamps that start instantly without pre-heating the cathodes and without the need for starters. 2) A type of ballast designed to start fluorescent lamps as soon as the power is applied. Most T8 fluorescent lamps are being operated on electronic instant-start ballasts.

KILOWATT HOUR (kWh):
The standard measure of electrical energy and the typical billing unit used by electrical utilities for electricity use. A 100-watt lamp operated for 10 hours consumes 1000 watt-hours (100 x 10) or one kilowatt-hour. If the utility charges $.10/kWh, then the electricity cost for the 10 hours of operation would be $0.10.

LAMP LIFE:
An average rating, in hours, indicating when 50% of a large group of lamps have failed, when operated at nominal lamp voltage and current; every lamp type has a unique mortality curve that depicts its average rated life.

LIGHTING UPGRADE:
A term which can apply to either an energy efficiency or light level improvement project.

OCCUPANCY SENSOR:
Control device that turns lights off after the space becomes unoccupied. May be ultrasonic, infrared, combination or other type.

POSITIVE CASH FLOW:
When referred to as part of a lighting upgrade, this is a comparison of estimated savings to cost. With 100 percent project financing it is possible to have an immediate positive cash flow once the project starts.

RAPID START:
A fluorescent system that does not require starters and takes 1 to 2 seconds to emit light. The ballast preheats the electrodes within the fluorescent lamp and initiates the arc without a starter or the application of high voltage.

RELAMPING:
A project where the existing lighting fixtures at a facility are, as a group, cleaned and new lamps are installed. This is typically scheduled around projected life expectancy to reduce the day-to-day interruptions of failing aged lamps.

SHARED SAVINGS:
A project where a building owner pays a lighting contractor a portion of the savings realized through the installation of energy efficiency products at the owner's facility. The term of the program varies based on existing technology currently in use.

T8 LAMP:
Industry standard for a fluorescent lamp that is eight one-eights (one inch) in diameter. Other typical sizes include T10 (1.25 inches) and T12 (1.5 inches) in diameter. The Color Rendering Index (CRI) is usually higher than a standard T12 lamp.

T12 LAMP:
Industry standard for a fluorescent lamp that is 12 one-eighths (1.5 inches) in diameter. Other typical sizes include T10 (1.25 inches) and T8 (1 inch) lamps.

TROFFER:
A large recessed luminaire (light fixture) that often uses several fluorescent lamps, measures 24in by 48in, and is usually installed with the opening flush with the ceiling. 2) The term used to refer to a recessed fluorescent light fixture (combination of trough and coffer).