On Wed, 12 Dec 2012 05:32:08 -0800, "William Sommerwerck"
wrote:

Even a slight drop in voltage causes a big increase in life. For example,
a 5% reduction almost doubles the lamp's life (1.85 times). At a 10%
reduction, the lamp lasts 3.5 times as long.

I guess the question becomes: is there some voltage a bit below normal,
where the halogen cycle doesn't work and lamp life actually degrades?
I'm guessing no.

I'm guessing yes. A friend had halogen lamps on a dimmer, which he dimmed
only slightly -- and they burned out pretty quickly.

The halogen cycle requires a very high temperature. Ergo...

If there's almost no filament evaporation, who cares if the halogen cycle isn't
working? It's not needed. And it will work if full line voltage is applied
occasionally.

Our kitchen-table halogen is dimmed and is over 10 years old, on the original
bulb.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

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