Lighting Terminology for Dummies

Lighting Terminology for Dummies

By oeo2018 • Jan 8th 2018



Accent Lighting:  Focusing light on a particular space or object.   Intended to create visual interest in an area or object.   


Alternating Current (AC):  Electric Current in which the flow of electric charge reverses direction at regular intervals.  


Amps (A): Standard Unit of  Measurement of electric current.




Ballast: A device used to regulate current and voltage to start and operate a lamp.   Ballasts are used with HID and Fluorescent light sources.

Ballast Factor: Indicates the percentage of rated light output and power that can be expected of a lamp.




Candela (cd):  Measurement of luminous intensity of a source in a given direction.


Center Beam Candle Power (CBCP): Luminous intensity at the center of a light source beam


Color Rendering Index (CRI): A Measure of a light sources ability to show colors accurately.  The Scale is from 1 to 100.  The sun is considered 100.


Color Temperature: Correlated Color Temperature (CCT).  A measurement of hue of the light produced by a source.  




Diffuser: A device used to alter light by scattering it in order to create softer light with minimal glare


Dimmer: A device used to control the light output of a light source.


Direct Current: Electrical current that flows in only one direction without cycling.  DC current is most commonly used with batteries and PV cells.


Direct Replacement: it's as simple as Plug-N-Play! Direct replacement LED lamps from OEO screw into your existing fixture without the need to rewire or upgrade while helping to save you up to 84% on energy costs.


Driver: Electrical or electronic circuit that controls other components.  In LED Lighting Systems, the driver regulates the power to the LEDs.




Efficacy: Lumens per Watt of a light source


Electromagnetic Interference: Disruption of an electronic device by an external source by electromagnetic induction, electrostatic coupling, or conduction.


Electronic Ballast: Ballast composed of electronic components instead of the core-and-coil transformer.  Electronic ballasts do not experience as much power loss as magnetic ballast.




Fluorescent Lamp: Low Pressure Mercury-Vapor-Gas-Discharge Lamp that uses fluorescence to produce visible light.   Fluorescent lamps require a ballast for current and voltage regulation.




Glare: Glare is a visual sensation caused by excessive brightness.  It can be discomforting or disabling.  




Halogen Lamp: Halogen Lamp is a type of incandescent lamp that incorporates halogen in order to increase the average life and light output of the light source.


Heat Sink: 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: Type of Light Fixture typically used for commercial and industrial applications with high ceilings (>20 ft).


High Intensity Discharge Lamp: HID Lamps.   Family of electrical gas-discharge lamps that produce light by means of electrical arc.  


High Pressure Sodium Lamp (HPS): Type of High Intensity Discharge Lamp.  Frequently used in street and outdoor lighting applications.  




Illuminance: Measured in Lux or Footcandles,  Illuminance is the total luminous flux on a surface.  


Initial Lumens: Total luminous flux of a light source at the beginning of its life.




Kelvin Temperature (K): Unit of measurement of the Correlated Color Temperature 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 more efficient than other light sources and offer exceptionally long life


Lumen: Standard unit of measurement of luminous flux.  Used to measure the total quantity of visible light emitted by a light source.


Luminaire: Light Fixture.  A complete unit consisting of lamp, ballast, reflectors, lens, and other parts.   




Magnetic Ballast: Often Called "Core-and-Coil" ballast. Magnetic ballasts contain a magnetic core with copper windings.  Magnetic ballast typically have greater power losses than electronic ballasts.


Mean Lumens: Average luminous flux produced by a light source over the duration of its rated life.


Metal Halide Lamp: High intensity discharge lamp that generates light by passing an electric arc through a mixture of mercury and metal halide gases.








Photocell: Light Control that turns a light source on/off depending on daylight


Power Factor: The ratio of real to apparent power supplied to a circuit.   Power factor can range from 0 to 1.   






Reflection: Light bouncing off a Medium.


Refraction: Bending of light as it passes through a medium.  The bending in light is a result of the change of speed as it 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.


Retrofit:  Upgrading old and inefficient technology with new equipment to improve the  efficiency of a light system










Voltage: Potential Difference in charge between two points in an electrical field.  Measured in Volts (V).


Voltage Drop: Loss of voltage caused by resistance.  Voltage Drops can be created by too long or too think wire.   




Wall Pack: The most widely used commercial outdoor lighting fixtures used today. Wall packs are powerful light fixtures that are installed in outdoor locations of commercial buildings.


Watt: Standard unit of measurement for power.   One Watt Equals one Volt-Amp.