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What do Bulb Letters Mean?


Strip Light

Strip Light

Question: What do Bulb Letters Mean?
Answer: In answer to the reader question:
"I recently purchased a used strip light at a flea market and have no manual for it. I know it's florescent, and I can measure the length of the light, but that's all the info I have. The light bulb inside has some letters and numbers, which I assume mean the kind of bulb I should use. Can you tell me what the bulb letters mean? Thanks."

Like most lamps, yours has been stamped with a series of letters and numbers that provides information about it. Although each manufacturer has their own set of codes, they follow some basic standards that should allow us to determine exactly what kind of lamp you have.

Type and Length
Odds are your light is fluorescent, since that majority of strip lights are. You can tell easily enough by looking at those bulb letters you mentioned. Fluorescent lamps all begin with an F to indicate they are fluorescent, generally followed by a number indicating the length in inches. So an F48 would be a fluorescent lamp that is four feet (48 inches) in length. Circular fluorescent lamps will have an FC designation, and U-shaped or bent lamps will be labelled FU or FB.

Shape and Diameter
The shape of the lamp is often the next designation. In your case you should have a T, which indicates you have a tube shaped lamp (the type found in strip lights). The number following the T indicates the diameter of the tube. Generally you can divide the number by 8 to determine the diameter in inches. Thusly, a T8 tube would be one inch in diameter.

The diameter is important due to the fact that tubes of the same length may not fit in the same fixture due to the diameter of the tube. When purchasing an aquarium fixture (new or used) it's wise to find out what diameter tubes it will take.

With the advent of mini-aquariums, smaller tubes are becoming more widely available. However, T8 is still the most common small sized used in aquariums, while T12 is the largest size typically seen in aquarium use. Here are some common tube sizes:

T6 = 3/4 inch in diameter
T8 = 1 inch in diameter
T10 = 1 1/4 inches in diameter
T12 = 1 1/2 inches in diameter

Additional Parameters
On some tubes you may also see other letters indicating the light type (ie: warm or cool), output of the lamp, type of start (ie: rapid-start lamp), and even an energy-savings designation. Those types of designations will vary somewhat from one manufacturer to the next.

Some examples of such codes are C for cool, W for warm as well as white (ie: CW indicates cool white, while WW indicates warm white), HO for high output, RS for rapid-start, and ES for energy saving lamp (one that draws fewer watts).

Hopefully this helps identify your lamp. You might also find this Aquarium Fixture Guide helpful to determine what size tank your strip light is intended to fit. Good luck!
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