Knowledge about LED lighting

• LED Lifespan

  LEDs do not burn out like an incandescent light bulb.  Instead they get progressively dimmer over their lifetime until they no longer emit enough light to be useful. The time that this takes is often referred to as the “rated life” of an LED.  While some LEDs may have a rated life of 100,000 hours, this is usually only under perfect laboratory conditions.  Under real-world conditions most LEDs operating in light fixtures might last up to 60,000 hours.

• LED Color Temperature

  Color temperature is a measure of the color appearance of a light source which helps describe the apparent “warmth” (reddish) or “coolness” (bluish) of that light.  Light sources below 3200 Kelvin (3200K) are considered to be “warm;” while those above 4000K are considered to be “cool” light sources.  For comparison, a traditional household incandescent light bulb is 2800K.   White LEDs vary in color temperature. 
  

• LED Color Rendering

  Color rendering index (CRI) is the ability for any light source to render colors accurately.  The CRI scale goes from 1 (low pressure sodium) to 100 (the sun).  A CRI of 75 is considered to be good, a CRI of 85 is considered to be very good, a CRI of 95 is considered to be excellent. LEDs in a warm white color temperature are currently available with a CRI of 80.

• LED Drivers

  Fluorescent light bulbs require a ballast in order to function.  The ballast provides a starting voltage and limits the electrical current to the light bulb.  LEDs also require a similar electronic power source.  For LEDs, this electronic power source is usually called an LED driver.  The LED driver converts line power to the appropriate voltage and current , and may also include dimming and/or color correction controls. 
  

• LED Brightness

  A single high power LED is not as bright as a 60 watt incandescent light bulb.  In order to produce adequate lighting, therefore, an LED fixture must contain groups of LEDs.  However, the future is bright, pun intended, for LEDs.  The lumen output of LEDs has almost doubled in the last two years.
  

• Infrared and UV Radiation

  LEDs do not emit infrared, or heat, radiation like an incandescent light bulb.  In addition, LEDs do not create ultraviolet radiation (UV rays) like a fluorescent light bulb.