The lighting industry uses many terms that are not often used or known elsewhere. Familiarize yourself with several common terms used in the lighting industry with this comprehensive glossary guide.
A
Accent Lighting: Light that focuses on a particular space or object, often intended to create visual interest in an area or object.
Alternating Current (AC): An electric current in which the flow of electric charge reverses direction at regular intervals.
Amps (A): A unit of measurement used to calculate electric current.
B
Ballast: A device used to regulate the necessary current and voltage to start and operate a lamp.
Ballast Factor: An indicator of the percentage of rated light output and power that one can expect of a lamp. A higher ballast factor indicates greater light output and greater power consumption.
Beam Angle: The angle between two planes of light, where the intensity is at least 50% of the maximum intensity at the center beam.
C
Candela (cd): A measurement of luminous intensity in a given direction.
Center Beam Candle Power (CBCP): Luminous intensity at the center of a light source’s beam.
Color Rendering Index (CRI): The measure of a light source's ability to show colors accurately. CRI is measured on a scale of one to 100.
Correlated Color Temperature (CCT): A measurement of the hue of the light produced.
D
Diffuser: A device used to alter and scatter light to create softer light and minimal glare.
Dimmer: A device used to control the light output of a light source.
Direct Current: An electrical current that flows in only one direction without cycling. Direct current is most commonly used with batteries and PV cells.
Driver: An electrical or electronic circuit that controls other components. In LED systems, the driver regulates power to the LEDs.
E
Efficacy: Efficacy refers to the lumens per watt for a light source.
Electromagnetic Interference: The disruption of an electronic device by an external source through electromagnetic induction, electrostatic coupling, or conduction.
Electronic Ballast: A ballast composed of electronic components. Electronic ballasts are more efficient than magnetic ballasts.
F
Fluorescent Lamp: Low-pressure mercury-vapor-gas-discharge lamp that uses fluorescence to produce visible light.
Foot-Candle (FC): A unit of measurement used to calculate illuminance. One foot-candle is equal to one lumen per square foot.
G
Glare: Glare is an often-uncomfortable visual sensation caused by excessive brightness.
H
Halogen Lamp: A type of incandescent lamp that uses halogen to increase the average light output of the light source.
Heat Sink: A device incorporated in LED lighting systems to disperse heat away from the LED diode.
Hertz (Hz): The standard unit of measurement for frequency. One Hz equals one cycle per second.
High Bay: A type of light fixture typically used for commercial and industrial applications in areas with high ceilings.
High-Intensity Discharge Lamp: HID lamps are the family of electrical gas-discharge lamps that produce light through an electrical arc.
I
Illuminance: Illuminance is the total luminous flux on a surface. It is measured by lux for foot-candles.
Ingress Protection (IP) Ratings: A measurement of environmental protection for electronic equipment that utilizes digit rates for ingress of solid objects and liquids.
Initial Lumens: The luminous flux of a light source at the beginning of its life.
K
Kelvin Temperature (K): The unit of measurement for the CCT of a light source.
L
Lamp Base: The portion of a lamp that connects to the luminaire socket and power.
Light Emitting Diode (LED): A semiconductor device that emits light as electrical current passes through it. Light-emitting diodes are known as LED lights and are more efficient than other light sources.
Lumen: A standard unit of measurement of luminous flux, which is used to measure the quantity of visible light emitted by the light source.
Luminaire: A complete unit consisting of lamp, ballast, reflectors, lens, and other parts, also known as a light fixture.
Luminaire Efficiency: Luminaire efficiency refers to the lumens emitted by a light fixture compared to lumens emitted by the lamp source used in the fixture.
Lux: A unit to measure illuminance. One lux equals one lumen per square meter.
M
Magnetic Ballast: A magnetic ballast contains a magnetic core with copper windings. Magnetic ballasts typically have greater power losses than electronic ballasts and are commonly known as "Core-and-Coil" ballasts.
Mean Lumens: The average luminous flux produced by a light source over the duration of its rated life.
Mercury Vapor Lamp: A high-intensity discharge lamp that creates light by passing an electric arc through vaporized mercury.
Metal Halide Lamp: A high-intensity discharge lamp that creates light by passing an electric arc through a mixture of mercury and metal halide gases.
P
Photocell: The light control that turns a light source on and off, depending on daylight.
Power Factor: The ratio of real to apparent power supplied to a circuit. The power factor can range from zero to one.
R
Radio Frequency Interference: A form of electromagnetic interference in the radio frequency spectrum.
Reflection: The light bouncing off an object or medium.
Refraction: The bending of light as it passes through a medium, which is a result of the change of speed as the light passes from one medium to the next.
Restrike Time: The time it takes for a lamp to reach full brightness after being turned off and back on again.
Retrofit: Upgrading technology with new equipment to improve the efficiency of a light system. LED retrofit light kits are commonly used when retrofitting to switch to LED light sources.
T
Transformer: An electrical device that transfers electricity from one voltage to another. Step-down and step-up transformers are used to take high voltages to lower voltages and vice versa.
V
Voltage: The potential difference in charge between two points in an electrical field.
Voltage Drop: A loss of voltage caused by resistance, such as a wire that is too long or too thin.
W
Watt: A unit of measurement for power. One watt equals one volt-amp.
These are all common terms used in the lighting industry. Familiarize yourself with these terms to gain a greater understanding of what to expect when improving your home or business’ light sources.
