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How long can a metal halide lamp last

  1. Aug 15, 2011 #1
    I'm doing a story for our paper on this outdoor must be mercury or metal halide light that's been burning constantly at least since 1996. So says the owner who took over the property then. He says the photo switch isn't working so it never shuts down. And-there are two others nearby with good switches that are burned out. It does look a little dim.
  2. jcsd
  3. Aug 17, 2011 #2
    Metal halides have an average lifespan of 20,000+ hours. They are meant to be turned on a left on and do not like to be restarted. 1996 seems like a long time, but I guess anything is possible. The fact that its been continuously burning is one major factor that would lead to its longevity.
  4. Aug 17, 2011 #3
    A local contractor told me mercury vapor lamps will last forever but they do dim over time. and yes no on/off cycles likely added to it's longevity.
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