"hungry1" wrote in message
news:1103993274.1ab3a0becb9f018c0d9c4d5e6a1108d6@t eranews...
Could someone tell me what might be the cause of a mercury vapor light to
intermittantly go off and in a few minutes come back on? It doesn't do it
consistantly, but rather often.
Thanks,

--
curt



Mercury lamps rarely do this, but I have seen some of the cheap Chinese made
lamps cycle when they reach end of life. A guy I know had a 100W one that
only lasted 3 months, sure a big step down from some of the 60's vintage
Westinghouse and GE lamps that happily ran for 20-30 years.

Most HPS lamps will cycle when they age and the emissive material wears off
the cathodes, Metal Halide lamps will often suffer an arc tube rupture
before this happens, in lighting industry terms a "non-passive" failure but
what it usually comes down to is a shower of red hot quartz shards and
broken glass. This is why it's important to always have the cover in place
when operating these lamps.