Lutron Glossary of Terms - LED Technology
Light Control Education
1% (architectural dimming)

A system that has a lowest achievable light level of 1% of its maximum measured light output; 1% measured light is perceived as being dimmed to only 10%. Used in applications such as conference rooms, theaters, restaurants, and retail spaces.

5% (high performance dimming)

A system that has a lowest achievable light level of 5% of its maximum measured light output; 5% measured light is perceived as being dimmed to only 22%. Used in applications such as residences, lobbies, and small meeting rooms.

10% (lighting management dimming)

A system that has a lowest achievable light level of 10% of its maximum measured light output; 10% measured light is perceived as being dimmed to only 32%. Used in applications such as private and open offices, classrooms, stairwells, and restrooms.


The grouping of LEDs (from production) according to specifications, such as light output, color, and voltage so that LEDs of similar light performance are grouped.

Dimming range

Ratio of minimum to maximum measured light, usually expressed as a percentage.


Auxiliary device(s) needed to operate and vary the intensity of light output from LED lamp source(s) by regulating the voltage and current powering the source.

Driver rating

Parameters that define the operating power level output. The rating also includes both input and output specifications (voltage, current, frequency, etc.).


Noticeably unstable light output, usually involving large, quick changes in light intensity.

General illumination

Lighting (usually white) that illuminates spaces or surfaces, as opposed to accent lighting or indicator lights.


A Lutron fluorescent ballast and LED driver family with a dimming range of 100–1%. Ballasts are available for most fluorescent lamp types.


The quantity of light, in candelas, emitted by a source in specific directions. Using these values, a diagram can be compiled that provides a direct impression of the light distribution from a lamp /luminaire combination.

LED (Light emitting diode)

A solid-state light source that uses multiple arrays of “white” or RGB (red/blue/green) light emitting diodes as a low wattage, low temperature source. LED arrays cannot operate without a driver, a fixture, and a control. These components must all be compatible in order to ensure that their integrity is maintained. It is an extremely long-lived light source, which also produces very little heat on the object being illuminated.

LED array (also called an LED light engine)

A device that incorporates LEDs into a package that may then be integrated into a fixture. It typically integrates multiple LEDs onto a PCB (printed circuit board) and may be replaceable.


Any device, which draws power from a power distribution system, such as a lighting fixture from a power circuit.

Lumen (lm)

A unit of measurement of light energy. Specifically, lumens measure the amount of light an electric source (lamp) produces in all (360 degrees) directions (e.g. a candle gives off ~12 lumens, while a 100 W A19 incandescent lamp gives off ~1,650 lumens and a 4 ft 32 W T8 fluorescent lamp gives off ~3,100 lumens). The higher the number, the more light is emitted.“Lumens per watt (lm/W)” measures the efficiency of a light source.

Luminous efficiency

The ratio of light emitted to the power required for a light source or luminaire (usually expressed in lumens per watt). Commonly used to measure energy efficiency, it is the lumens per watt from a light source (amount of light per watt of power).

Phosphor conversion

A method used to generate white light with LEDs and fluorescent lamps. A blue or near-ultraviolet LED is coated with a yellow or multi-chromatic phosphor, resulting in white light. A fluorescent lamp uses the same principles by converting an ultraviolet arc to visible light through the use of phosphors.

Red, Green, Blue (RGB)

A method used to generate white and other mixed colors with LEDs. It stands for red, green, and blue – the 3 primary colors of light. When the primaries are mixed, the resulting light appears white to the human eye.


Small changes in light intensity. This can usually only be noticed at medium to low light levels, and often only at the periphery of vision.

Smooth and continuous

Refers to the quality of the change in light level when the command control is varied. There should be no flicker or jumps in light level output.

Thermal management

The overall process by which the heat generated by the LED is directed away from the semiconductor device and eventually removed from the fixture. It can be any mechanical means, either active or passive.

UL listed

A product adhering to the standards of Underwriters Laboratories, a company nationally recognized for product safety testing (the product is not "approved" nor tested for performance). Underwriters Laboratories was initially created by insurance companies to reduce fire risks. In Canada, CSA is the listing required.