What Are T12 Lamps?

T12 Lamps

• The diameter of the lamp tube determines its size and name. A T12 lamp has a diameter of 1 1/2 inches and is available in a number of lengths. T12 lamps comprise about 30 percent of the fluorescent lamps sold in the U.S. They light offices, schools, stores and many other commercial buildings.

T12 Phaseout

• The diameter of the lamp tube determines its energy efficiency. In general, the narrower the bulb, the more energy efficient it is. The bulkier T12 is now being taken off the market to make way for lamps such as the T8, which is less of an energy hog. Manufacturing for the magnetic ballasts, which control the output of light and color, for the T12 ceased July 1, 2010. Manufacture of many T12 lamps are being phased out as well.

Higher-Efficiency Options

• More efficient T8 and T5 lamps can provide more lighting using less energy. For example, a T12 four-lamp F34T12 light with a magnetic ballast consumes 148 watts of electricity, while a T8 four-lamp F32T8 light with a high-efficiency ballast uses 96 watts. In addition, light level is increased by 3 to 12 percent.

Saving Money

• Light systems have to be replaced to accommodate non-T12 lamps, but the cost can be recouped in one to three years, according to Northeast Utilities, which suggests that cost savings from replacing T12 lamps can be as high as 45 percent. In the example in which a four-lamp T12 fixture is changed to a T8, $30.72 can be saved per year for each fixture, according to Universal Lighting Technologies, a lighting manufacturing company.