Fluorescent lamps are identified by a standardized code that reveals valuable information about operating characteristics and physical dimensions. Manufacturers' codes, found on the lamps and in catalogs, may vary slightly from the generic designations. However all major lamp manufacturers base their codes closely on the identification system discussed below.
The best way to learn lamp identification is through example. Below is a range of fluorescent lamps, one for each popular starting method:
Rapid-Start (40 Watts or Less) and Preheat Lamps
Rapid-start lamps are the most popular fluorescent lamp type used in commercial applications such as office buildings.
To learn more about what "cool" and "warm" means in terms of the color quality of light sources, see Color Metrics.
Note that some lamps may be designated F40T12/ES, but the lamp draws 34 instead of 40 watts; the "ES," a modifier which stands for "energy-saving," indicates this. ES is a generic designation; actual manufacturer designations may be "SS" for SuperSaver, "EW" for Econ-o-Watt, "WM" for Watt-Miser and others.
After the mode of starting, another number may be added to indicate color rendering and color temperature if the lamp's color (CW, WW, WWX, etc.) is not indicated. The number will often be three digits, the first indicating color rendering (a "7" standing for "75," for example) and then the next two indicating color temperature (a "41" standing for "4100K," for example).
High-Output Rapid-Start Lamps
Very High-Output Rapid-Start Lamps
Other Fluorescent Lamps
"FC" instead of "F" means the lamp is circular.
"FB" or "FU" instead of "F" means the lamp is bent or U-shaped. The suffix "U" can also be used for U-shaped lamps, followed by a "/" and a number that indicates the distance between the lamp's legs in inches. "FT" instead of "F" is used for twin-tube T5 lamps.
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