What causes the lamp assembly to burn out when touched with fingers?

Dustin Liu

Banned
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Oct 14, 2005
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182
Hi, I am just wondering why/how when someone touches a light bulb with their fingers how it will decrease the life expectancy of the lamp assembly (what causes it).

:whistle::whistle::whistle::whistle::whistle:
 

atm

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Dec 19, 2005
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Australia
Good question, I remeber it had something to do with the oil from the skin, quote below from:

http://www.electrical-online.com/howtoarticles/Lighting/Halogen.htm

When replacing any halogen bulb, do not touch the glass envelope. The salts in your skin oils penetrate and weaken the glass. The bulb not only has a shorter life, but when the bulb dies the filament doesn't merely burn out, but rather the bulb envelope shatters. The light bulb industry calls it a "non-passive failure."

I imagine the same applies for bulbs other than Halogen also.

Andrew
 
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jeffroalpha700

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Oct 24, 2004
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It is the oils in the skin. The oils will also heat and not allow the same thermal dissipation in the air around the bulb. This will cause the bulb to overheat again shortening the life of the lamp assembly.
 
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Dustin Liu said:
Hi, I am just wondering why/how when someone touches a light bulb with their fingers how it will decrease the life expectancy of the lamp assembly (what causes it).

:whistle::whistle::whistle::whistle::whistle:

It's the salt in your finger. Many of these bulbs are "quartz glass", but when it is mixed with salt at high temperature, the sodium will migrate into it turning that section into "soda glass" and fracturing it.
 
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