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Self-Ballasted Mercury Vapor

Mercury vapor lamps exist in a self-ballasted version that contain either a solid-state starting device or an incandescent filament that acts as a ballast. The solid-state type of lamp should not be used in a totally enclosed luminaire because of the heat build-up associated with this lamp.

In general, self-ballasted mercury vapor lamps are 50 percent less efficient than standard mercury vapor lamps, but 50 percent more efficient than incandescent lamps. They should be limited to short term replacement of incandescent lamps where relamping is difficult and ballast addition impractical.