Failure Metal High Halide Lamp

1. Voltage spike?

2. Did someone insert the lamp with bare fingers, which is a no-no?

Vibration?

Frequent switching on and off?

Voltage consistently too high?

Is the inner surface of the glass blackening on the lamps which have not yet failed?

Be sure the correct wattage of bulb is used, as someone who had never worked with HID lamps, I tried to replace a 400W bulb with a 175W bulb, hoping to save a little money on electricity. We didn't get more than a couple of months out of that lamp. It was then I found out that the ballast on Metal-Halide lamp fixtures is designed to drive a certain wattage lamp.

Also, I believe there are lamps made for different bulb orientations, such as base-up, base-down, or universal, which can be installed in any orientation. If you install a "base-down" lamp in a "base-up" fixture, I would expect to see a decreased life expectancy on that bulb. Just some random thoughts.......

Tom D.