Common Terms Used in the Lighting Industry

Common Terms Used in the Lighting Industry

  • Adorn Themes Collaborator

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.  

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. 

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. 

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. 

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. 

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. 

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. 

Glare: Glare is an often-uncomfortable visual sensation caused by excessive brightness.  

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.   

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.  

Kelvin Temperature (K): The unit of measurement for the CCT of a light source. 

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. 

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.  

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. 

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. 

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.  

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.  


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.

Common Terms Used in the Lighting Industry


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