Jinx wrote:
>
> > Inadequate ventilation, allowing excessive heat build up?
>
> Open metal housings
>
> > Large spikes on the power line?
>
> Horrible coincidence if there's one always EXACTLY at turn on
>
> > Multiple hard on/off cycles?
>
> Once on at sunset, once off at bedtime. That's about as kind as
> you could be
>
> > Excessive vibration?
>
> Fixed firmly to walls and ceilings
>
> > Seems to me that it would be far better to correct the problem
> > than to waste 5% or 11% of the electricity you are buying
>
> I agree, if there was an identifiable cause other than the obvious
> wear and tear through under-rated manufacturing. I betcha bulb
> mftrs could make bulbs last a damn sight longer if they wanted
> to. Resistors are an acceptable $10 one-off alternative to spending
> $50 a year on replacement bulbs. Besides, as the brightness
> hardly changes, what's the diff ?



I side with Jinx here, it is not always the users
fault when they get bad bulb life. Here in Australia
we have 240vac power, but it varies street to street.
I have had 220v, 260v!!, and lots of amounts in between
depending on where I lived and the current load at that
time of day. And I do measure it! :o)

People with a 110v mains may not understand what it
is like to have a cupboard full of light bulbs and put
them on regular shopping list!

I showed the calcs in a post before, the cold resistance
of a 240v 60w bulb I measured at 60 ohms. Let's assume
a 110v 60w bulb is 30 ohms cold.

At worst case (50% chance, turn-on near peak AC volts):
240v 60 ohm, = 340v peak = 1900w cold
110v 30 ohm, = 155v peak = 800w cold

So even though the bulbs are both 60w, the US
bulb has less than half the turn-on surge power
AND has a filament about twice as thick (strong).

We had 3x 100w sealed spotlights on the awning of
one of our TV repair shops, and we were replacing a
bulb just about every week. If we still owned that
shop I would have 5% loss resistors in there now!
:o)
-Roman

PS. Jinx, you spent $10 on a 10w resistor??????
I can get 5w resistors here in any shop for about
60c each!

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