"James Sweet" writes:

wrote in message
...
These are 40W Wagner 795 halogen bulbs used in an automotive light
bar. They failed prematurely. We were very careful installing them

How did they fail?

that they were never touched by hand. So I have some questions:
1. Why is it that touching halogen bulbs can decrease their life? This
is a sealed bulb.
2. Should we clean them with 99% isopropyl before installing them?
3. Does anyone have any ideas as to why these failed prematurely?
Thanks, Lenny.

Finger oils can burn and darken, creating a hot spot on the quartz.

Yes cleaning them would be a good idea.

How prematurely? Lots of things can cause early failure. Defective
manufacturing, poor handling, excessive vibration, excessive voltage, etc.

Also, there's a range below spec'd power where life will be reduced
since it's not hot enough for the halogen cycle to work properly.

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