Electricians' toolbox

Lighting Definitions

Accent Lighting - Directional lighting to emphasize a particular object or draw attention to a part of the field of view.

Ambient Temperature - Temperature surrounding a lamp, luminaire,etc.

Andonizing - Any electrolytic or chemical process by which a protective or decorative film is released on a metal surface.

Asymmetric - Unequal distribution about one or more axes.

Ballast - An auxiliary electrical device for fluorescent and other discharge light sources.

Candlepower (or Candela) - Basic unit for measuring luminous intensity from a light source in a given direction.

Coefficient of Utilization - The amount of light (lumens) delivered in a workplane as a percent of the rated lumens of the lamp.

Cold Cathode Lamp - An electric-discharge lamp whose mode of operation is that of a glow discharge (Neon Lights).

Cove Lighting - Distributes light over the ceiling and upper wall.

Diffuser - A device to redirect or scatter the light from a source.

Footcandle (fc) - The unit of illumination when the foot is taken as the unit of length. It is the illumination on a surface one square foot in area on which there is a uniformly distributed flux of one lumen.

Footlambert (fl) - A unit of luminance (photometric brightness) equal to one candela per square foot.

High Intensity Discharge Lamps (H.I.D.) - A general group of lamps consisting of mercury, metal halide, high pressure sodium, and low pressure sodium lamps.

High-pressure Sodium Lamps - A sodium vapor in which the partial pressure of the vapor during operation is the order of 0.1 atmospheres.

Hot Cathode Lamp - An electrical discharge lamp whose mode of operation is that of an arc discharge.

Illumination - The density of the light flow incident on a surface.

Infrared Lamp - An electrical device that emits infrared rays - invisible rays just beyond red in the visible spectrum.

Incandescent Filament Lamp - A lamp in which light is produced by a filament heated to incandescence by an electrical current.

Kilowatt Hour (KWH) - The work performed by one kilowatt of electric power in one hour. The unit on which the price of electrical energy is based.

Louver - A series of baffles used to shield a source from view at certain angles or to absorb unwanted light.

Lumen - The derived SI unit for luminous flux; unit measure of light.

Mercury Lamps - An electric discharge lamp in which the major portion of the radiation is produced by the excitation of mercury atoms.

Metal Halide Lamps - A discharge lamp in which the light is produced by the radiation from the mixture of metallic vapor and the products of disassociation.

Reflector - A device used to redirect the light flow from a source by bouncing it off the surface.

Refractor - A device used to redirect the light flow from a source, primarily by bending the wave light.

Symmetric - Equal distribution about one or more axes.

Troffer - A recessed lighting unit, installed with the opening flush with the ceiling.

Tungsten-Halogen Lamp - A gas filled tungsten incandescent lamp containing proportion of halogens.