What is LED?

A Primer in LED Lighting

Some common terms that are used in the field of lighting.

Incandescent Light:

A type of lamp with a tungsten filament that glows when it carries current. Incandescent lighting has a perfect color-rendering index of 100, comparable to that of the sun, but is among the least efficient types of lighting.


CFL stands for Compact Fluorescent Lamp, also called compact fluorescent light, energy-saving light and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent light bulb; some types fit into light fixtures designed for incandescent bulbs. 

What does “LED” mean:

LED are the initials for Light-Emitting Diode. LED bulbs differ from traditional lamps in the way they produce light. While incandescent light bulbs pass electricity through a filament, LEDs produce light through the use of a semi-conductor that emits light energy when an electrical current is passed through it.

  • LED bulbs use solid-chip technology and, therefore, can be made very small and in various configurations, from under the cabinet track lighting to, colored lights along the ceiling and floor.
  • LED lighting has moved far beyond its initial technology of the 1960s and the bluish hues associated with LED lighting of the early 2000s. LEDs are now available in a wide spectrum of intensities, colors, shapes and sizes.
  • And, bottom line, LED bulbs last longer and use less energy. Plus, LEDs don’t contain hazardous materials like mercury and lead which we’ve unfortunately lived with for years in fluorescent lighting. 

Lumens vs. Watts:

The big switch for consumers with LED lighting is moving beyond the concept of wattage — which is associated with brightness but, in fact, it measures energy use. Today’s bulb brightness is measured in lumens.

By comparison: Incandescent bulbs need about 60 watts and compact fluorescents (CFLs) need about 15 watts to produce 800 lumens of brightness. LED bulbs, by comparison, need only 10 watts to get to 800 lumens. 


Kelvin vs. Fahrenheit:

Another major change in our thinking about light bulbs is use of the color-temperature scale— which with LED is measured in Kelvin vs. Fahrenheit or Celsius. The higher the heat, the cooler the color (think of the color blue we see at the center of a flame).

The use of Kelvin is a more precise way to define the relative whiteness of a light source. To compare numbers, the light of a 60-watt incandescent bulb burns at about 2,700K (Kelvin) and 800 Lumens — for which, please note, you need only 10 watts of an LED bulb to get 800 Lumens. 

Take a look at the photo below. Can you see the difference. All the lamps have been retrofitted to 18W LED T8 tubes except the first three. The first three are 54W fluorescent T8 tubes


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