On Tue, 11 Jun 2002, Doug Butler wrote:

>Here in 110VAC USA we don't seem to have the problems you are having in
>220VACland.  Vehicle bulbs are even lower voltage, which may explain fewer
>blown bulbs.
>
>An identical bulb designed for a lower voltage will have a shorted thicker
>filament, which gives it more mechanical strength.

True, the main failure mechanism is a thinned filament spot that overheats
at startup. With a thick filament the unevenness of the surface correponds
to a much lower difference in area plus there is a lot more thermal
conductivity to neighboring cold areas. I think that the pitting effect
increases with some power of the ratio between surface evenness and
filament diameter.

Peter

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