6 Terms
Contributors in Lighting
Lighting
ampere
Construction; Lighting
The standard unit of measurement for electric current that is equal to one coulomb per second. It defines the quantity of electrons moving past a given point in a circuit during a specific period. ...
contrast
Construction; Lighting
The relationship between the luminance of an object and its background.
luminaire efficiency
Construction; Lighting
The ratio of total lumen output of a luminaire and the lumen output of the lamps, expressed as a percentage. For example, if two luminaires use the same lamps, more light will be emitted from the ...
coefficient of utilization (CU)
Construction; Lighting
The ratio of lumens from a luminaire received on the work plane to the lumens produced by the lamps alone.
reflectance
Construction; Lighting
The ratio of light reflected from a surface to the light incident on the surface. Reflectances are often used for lighting calculations. The reflectance of a dark carpet is around 20%, and a clean ...
hot restart or hot restrike
Construction; Lighting
The phenomenon of re-striking the arc in an HID light source after a momentary power loss. Hot restart occurs when the arc tube has cooled a sufficient amount.
power factor
Construction; Lighting
The ratio of AC volts x amps through a device to AC wattage of the device. A device such as a ballast that measures 120 volts, 1 amp, and 60 watts has a power factor of 50% (volts x amps = 120 ...
