Glossary | U.S. Green Building Council
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lamp life

the useful span of operation of a source of artificial light, such as bulbs. Lamp life for fluorescent lights is determined by testing three hours on for every 20 minutes off. For high-density discharge lamps, the test is based on 11 hours on for every 20 minutes off. Lamp life depends on whether the start ballast is program or instant. This information is published in manufacturers’ information. Also known as rated average life.