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What is a lamp code? How do I read one for a fluorescent bulb?

Last Updated: Jan 06, 2017 12:53PM EST
Lamp codes are an easy way to identify the characteristics and physical dimensions of fluorescent bulbs. These codes are universal and used by every manufacturer. Below is a quick reference guide on how to read a fluorescent bulb's lamp code.

Example: F25T8/730/ECO

The first letter, which is "F," identifies the bulb as a fluorescent. This is followed by two numbers that represent the wattage of the bulb. In the above example, it is 25 watts. The “T8” describes the shape of the bulb, which is a tube 8/8th in diameter or 1".

In the middle set of numbers, the “7” refers to the CRI. Also known as the color rendering index, this CRI means that this bulb is in the 70’s. It actually has a CRI of 75. Furthermore, the “30” refers to the Kelvin temperature. The bulb in this example is 3000K.
“730” = 75 CRI / 3000K – Warm White (WW)
“735” = 75 CRI / 3500K – White Light
“741” = 75 CRI / 4100K – Cool White (CW)
“750” = 75 CRI / 5000K – Natural Light
“765” = 75 CRI / 6500K – Day Light

Linear Fluorescent Suffix
“ENV” = Environment. This bulb has passed the test for low mercury.
“RS” = Rapid-Start. Preheat bulbs do not have “RS” as a suffix.
“HO” = High Output. This bulb operates on 800mA current.
“VHO” = Very High Output. This bulb operates on 1500mA current.

Other Fluorescent Bulbs
“FC” instead of “F” means the bulb is circular. “FB” or “FU” instead of “F” means the bulb is bent or U-shaped. The suffix “U” can also be used for U-shaped bulbs, followed by a “/” and a number that indicates the distance between the bulb’s legs in inches.

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