Metal Halide bulb failure mode ??

May 06, 2008 1 Replies

Am having first experience with an outdoor MH flagpole light fixture problem.



The bulb just gets a blue arcing or glow in the center of it, but won't fire to full brightness. Is this typical of just the lamp itself failing? Other than that the bulb looks normal (not darkened like a dead fluorescent)



TIA



MikeB


How old is the bulb? Has it worked properly before?

The bulb has an inner arc tube. How does that part look? That part usually gets fairly worn-looking long before it actually goes bad.

Is this bulb a replacement bulb for an original one that had a decent life? If so, is the replacement bulb the same wattage as the old one, and does it have an ANSI ballast compatibility code matching one on the ballast (or fixture)? Examples of these codes are M57, M90, M98, M110, M143, etc. Replacement bulbs should only be of the same wattage - changing wattage in either direction will cause shortened life and usually also poor operation or outright malfunction. In some cases, an incorrect metal halide bulb can fail to start at all, or explodes from being overpowered.

- Don Klipstein ( snipped-for-privacy@misty.com)

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