More Lighting Terms!

Ibulbsn continuing with our theme from our last blog post, we’ve found some more lighting terms that are widely used and rarely fully understood by our lighting consumers.




Total Radiant Energy

Previously, we spoke about the three different wavelengths of light, visible light, infrared and ultraviolet. Total Radiant Energy is the measurement that is used to describe the total of these three wavelengths.

Lumens per Watt

Lumens are a measurement tool to determine the amount of light that is produced in the visible spectrum. Lumens per Watt is the number of lumens divided by the total watts used to create the light. It can be helpful to use this number to know how bright the light will be.

Rated Lamp Life

Rated lamp life is a measurement tool used to determine how long the light source will last. The longevity of a light source is established through laboratory testing.  The scientists determine the “rated lamp life” by collecting a sample group of lamps and testing the source, subjecting it to several starts per day.  The length of time required for half of the lamps to burn out determines the rated lamp life.

This process is done differently for LED light sources. LEDs do not burn like the rest, and over time their brightness can diminish. The rated lamp life (example 50,000 hours) for an LED isn’t for when it burns out, it’s for when the LED will likely be shining at only 70 percent of it’s original brightness.


Many energy efficient light bulbs are made with the ingredient Mercury. Fluorescent lamps and high intensity discharge lamps are the most common types of bulbs with mercury in them. The ingredient can be harmful and toxic to humans in large amounts so caution when handling these products is always advised.