life of a metal arc lamp

**tregg** · 08-16-2011, 07:02 AM

What is the longest you could expect a mercury or metal halide lamp to last? A person I know showed me a lamp in his lot that he says has been on since he took over the property in 1996. The photo switch is not working so it never shuts off. It looks rather dim but it's on. And he says two other parking lot lights with working photo cells are burned out.

**jwelectric** · 08-16-2011, 11:37 AM

I have one that was installed pior to 1995 that is still going strong.

I have installed them and they not last a month

**jadnashua** · 08-16-2011, 02:12 PM

Like many things electrical/electronic, some of them don't last as long if you turn them on and off, but can last a very long time if just left on.

**jimbo** · 08-16-2011, 07:53 PM

Average life expectancy may be 20,000 hours. That means some last longer. Continuous on probably adds a lot of hours to the life expectancy.

hj · 08-19-2011, 06:14 AM

There is a light bulb in a fire station in California which has been burning non-stop since about 1910. It was only turned off once to move it to the new station.

**jwelectric** · 08-20-2011, 02:12 AM

http://www.centennialbulb.org/photos.htm to see this bulb

**jadnashua** · 08-20-2011, 10:40 AM

Just a comment, but have you ever had a lightbulb die except when you first turn it on? I suppose if you had a big surge it might go while on, but almost 100% of the failures occur when the initial surge is applied. this applies more to incandescent bulbs rather than arc types, but they often die then, too.