Linear Fluorescent Tubes

Fluorescent lamps convert more of the input power to visible light than incandescent lamps. A typical fluorescent lamps convert about 22% of the power input to visible white light. The efficacy of fluorescent tubes ranges from about 16 lumens per watt for a 4 watt tube with an ordinary ballast to as high as about 100 lumens per watt for a 32 watt tube with modern electronic ballast, commonly averaging 50 to 67 lm/W overall. Linear Fluorescent Tubes must have ballasts inside of the fixtures in order to make them work.

The size and shape of a bulb is designated by a letter or letters followed by a number. The letter indicates the shape of the bulb while the number indicates the diameter of the bulb in eighths of an inch. For example, “T12” indicates a tubular shaped bulb having a diameter of 12⁄8 or 11⁄2 inches. The following are some of the more popular bulb shapes and sizes.