100 year incandescent bulb outlasts webcam aimed at it

[PhotonWrangler]

That 100-year incandescent bulb at the Livermore, CA Fire Station has now outlasted the webcam that was pointing at it. Thomas Edison nods in approval.

[Paul520]

Maybe the next 10 too.

[blasterman]

Web cam might have lasted longer if it were plugged into to same power supply protecting the bulb from real world conditions.

[fyrstormer]

So what, is it severely underdriven or something?

[TorchBoy]

Very likely; whether deliberately manufactured to do so or by a quirk of filament making, I don't know.

[PhotonWrangler]

Based on the relatively dim yellow glow I would agree that it's probably underdriven. I'm guessing that the socket and wiring are pretty old and there might be some signifigant I/R drop in it. Or the filament was designed for a higher voltage, or both.

[hoongern]

Also, it is my understanding that incans generally on start up, during which it experiences the greatest stress. Assuming that this one is not turned off, it should be fine. However if they turned it off & on again, who knows what may happen?

[PhotonWrangler]

Also, it is my understanding that incans generally on start up, during which it experiences the greatest stress. Assuming that this one is not turned off, it should be fine. However if they turned it off & on again, who knows what may happen?

You are correct - most incandescent bulbs blow out when they're first turned on due to the sudden thermal shock. It's a good bet that this lamp would also go poof if they turned it off and on again.

[electromage]

Actually, I believe that at one point the light bulb was moved, it must have been turned off at the point.

[hoongern]

Actually, I believe that at one point the light bulb was moved, it must have been turned off at the point.

Yup, it has been moved, although not in recent years (last move was in 1976). It sure is impressive for lasting this far, but I wonder if it would survive another on/off cycle.

Ref: http://centennialbulb.org/facts.htm (Installed 1901, moved 1903, 1937, and some power outages, until its last move in 1976 where is now runs under a back-up generator)

[PhotonWrangler]

Ref: http://centennialbulb.org/facts.htm (Installed 1901, moved 1903, 1937, and some power outages, until its last move in 1976 where is now runs under a back-up generator)

Even a circuit running with generator backup has power interruptions. It takes a few moments for a generator to fire up after a power outage, and the transfer switch won't operate until the generator is up to speed and stabilized. Thus a commercial power failure could result in an outage of 10-30 seconds. The only way to avoid this is to have the bulb running on a UPS which is then backed up by a generator. So I'm wondering if this is actually the case.

[hoongern]

Even a circuit running with generator backup has power interruptions. It takes a few moments for a generator to fire up after a power outage, and the transfer switch won't operate until the generator is up to speed and stabilized. Thus a commercial power failure could result in an outage of 10-30 seconds. The only way to avoid this is to have the bulb running on a UPS which is then backed up by a generator. So I'm wondering if this is actually the case.

Yeah, it's running on a dedicated power supply, whatever it means.

"...if you used only 4-watt bulbs to light your home, and you had a dedicated power supply (as does The Centennial Light), your lamps might last a hundred years, too...." (http://www.roadsideamerica.com/set/lightbulbs.html)

It's also been stated that it's been running without any interruptions since 1976.

[TorchBoy]

You are correct - most incandescent bulbs blow out when they're first turned on due to the sudden thermal shock.

And magnetic fields.

[tylernt]

And magnetic fields.

I don't think tungsten is magnetic, though the two posts that hold it probably are.

I realize incans are dead technology by this point, but I wonder if a soft-start circuit would greatly extend their lifetime.

[TorchBoy]

I don't think tungsten is magnetic

Neither are the aluminium coins and cans crushed with magnetic fields here (for example).

I realize incans are dead technology by this point, but I wonder if a soft-start circuit would greatly extend their lifetime.

Yes, some of the hotwire folk do that with their overdriven bulbs so they don't die on startup every other time they turn their torches on.

[tylernt]

Neither are the aluminium coins and cans crushed with magnetic fields here (for example).

If you're regularly dealing with 3,000 joules, blown light bulbs are likely the least of your concerns.

[TorchBoy]

Mwa ha ha.

[bshanahan14rulz]

Light in my dad's bathroom was there since he moved in, about 22 years ago. Still nice and bright, and you KNOW it gets cycled multiple times in a day.