In article , nospambob wrote:

An article in papers several year ago discussed the bulb high in the
far reaches of the NY Opera House that had been burning for 40 years
and nobody had any idea where the switch was for it if there was one.

Every once in a while I hear about this lightbulb somewhere or that one
somewhere else that has been running for many decades or about a century.

Now for the kicker: How much electricity is being consumed and how much
light is the bulb producing? Answer: These super long life bulbs produce
about or less than half as much light as that produced by "standard"
incandescents of the same power consumption.

If you double your power consumption to get the same amount of light and
avoid changing lightbulbs, chances are you increase your electricity cost
more than you spent on lightbulbs.

Heck, incandescent traffic signal bulbs are only designed to last 8,000
hours. And surely labor cost of changing lightbulbs is high there.

If you have some special need for a lightbulb to last a century, get a
230 or 240 volt lightbulb and run it at 120V. At half voltage, power
consumption will be about 28-29% of rated, life will be a few thousand
times rated, and light output will be somewhere around 9% of rated.

- Don Klipstein )