LED 101

A helpful guide to better understand common lighting terminology.


A Light Emitting Diode (LED) is a semiconductor device that converts electricity into light. Most white light LEDs are coated with phosphors to change the color characteristics of the emitted light.

LED Driver Icon
LED Driver

LED drivers (also known as LED power supplies) are similar to ballasts for fluorescent lamps or transformers for low-voltage bulbs: they provide LEDs with the electricity they require to function and perform at their best.

LED Lighting Specifications
Beam Angle

The angular dimension of the cone of light from reflectorized lamps encompassing the central part of the beam out to the angle where intensity is 50% of maximum. Categories from narrow angle to wider angle are Spot, Narrow Flood, Flood, Wide Flood.

Color Temperature

A specification of the color appearance of a lamp, measured in degrees Kelvin (K). For example: 2200K = "candle light", 2700K = "warm white", 3000K = "soft white", 3500K = "bright white", 4000K = "cool white", >5000K = "natural white", and >6000K = "daylight".

Color Rendering Index (CRI)

A measure of the correspondence between the color of an object and its appearance under a light source. CRI>60 or >70 is considered to be not good and CRI >80 is considered to be very good. CRI =100 is equivalent to natural sunlight!

Efficacy (Efficiency)

The lamp's ability to convert electrical power to light output. Simply put, lumens/watts.

Lumens (Luminous Flux)

The measure of the perceived power of light, measured in lumens. Simply put, brightness!

TRIAC Dimmable

TRIAC dimmers are designed for resistive loads such as incandescent or halogen lights and have a significant installed base in the United States and worldwide.


A unit of electrical power. Lamps are rated in watts to indicate the rate at which they consume electricity.

Types of LED Light Fixtures

A multi-arm, decorative, often ornate ceiling light fixture that holds a number of bulbs.


An ornamental hanging fixture with no multiple arms where the glass or diffuser opening faces down.

Flush Mount

A light fixture that is attached directly to the ceiling with no gap between the light and ceiling.

Semi Flush

A light fixture that attaches to the ceiling with a stem or part that creates a gap between the fixture and ceiling.


A decorative lighting fixture with a flat side to be hung on a wall, that holds candles or lights.

Recessed LED Fixture Icon

Recessed lights are a type of lighting fixture installed into a ceiling or wall, flush with the surface.


Recognized as an NRTL in the United States and, in a similar capacity, as a Testing Organization and Certifying Body in Canada by the Standards Council of Canada. A product bearing the ETL Listed Mark is determined to have met the minimum requirements of prescribed product safety standards.


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