On Sun, 15 Jul 2018 08:54:08 +0000 (UTC), you wrote:
I made a fixture years ago for working under the car at night. Three 150W bulbs in ceramic bases. Not only could I see everything, but it warmed up the carport in the winter!The failure mechanism in an incandescent light is mainly related to
filament thinning as the tungsten evaporates slowly and is deposited
on the inside of the glass bulb. Eventually, the inrush current gets
that small higher resistance point up to where the filament just plain
For incandescents, the lifetime is related to the rated voltage to
applied voltage ratio. 10% more voltage, from what I've heard,
results in almost 1/10 the lifetime. 10% less, and you have a very
long life bulb. For those with choices, and 120 volts household (mine
is 122 to 123), use a 130 volt bulb to get very long life.
Now for CCFL and LEDS, well, no filament, so the failure mechanism (at
least completely for LEDS) is component failure generally due to
temperature (I ignore voltage spikes here). Some of the LED lamps get
rather hot, depending on whether the LED or the control electronics is
the problem heat source. We know what that does to the electronics.
Cheaply made is also a factor, of course. Anything in the commodity
market is generally made for lowest cost to manufacture traded off
against an acceptable failure/return rate.
There are carbon filament light bulbs (low temperature) that have been
operating for over fifty years. I have a fiber optics light source
for a microscope that has been working for several years (not
continuous), and is permanently set on the "LOW" setting.