
The Centennial Light, a bulb that's reportedly been burning for 113 years - ryan_j_naughton
http://priceonomics.com/the-mysterious-case-of-the-113-year-old-light-bulb/
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ars
This article is terrible, priceonomics I'm ashamed of you.

> raises questions as to whether it is a miracle of physics, or a sign that
> new bulbs are weaker. Its longevity still remains a mystery.

It's not mystery at all. All you have to do to make a bulb last forever is
derate it. The lower the temperature the longer it lasts, (and the less
efficient it is).

At the dull red glow this one is emitting it'll last forever.

> Instead, they began to collectively engage in planned obsolescence. To
> achieve this the companies agreed to limit the life expectancy of light
> bulbs at 1,000 hours

I expected better from priceonomics than to repeat urban legends.

You can trade off long life and high efficiency. All that agreement did was
decide that 1000 hours was a good trade off point, and standardize the
luminous efficiency of incandescent bulbs so all incandescent bulbs of a
specified wattage will be approximately the same brightness.

You can read about it here:
[https://en.wikipedia.org/wiki/Incandescent_light_bulb#Light_...](https://en.wikipedia.org/wiki/Incandescent_light_bulb#Light_output_and_lifetime)
\- it even mentions this very bulb.

Note that lifetime goes by the power of 16!!! so it's very easy to derate a
bulb and make it last forever.

~~~
stephenjwatkins
Just a note that a site moderator has responded to this reply in their
comments:

"First of all, we understand the correlation between low output and longevity,
and acknowledge that the Centennial Light produces a very low output. Even so,
out of hundreds of thousands of low wattage bulbs produced from 1880-1910,
it's the only bulb of its kind that has burned for 113-years. Just a handful
of bulbs on Earth are older than 60. We think that qualifies as mysterious on
some level -- even when scientifically dissected.

Secondly, I appreciate you clarifying the complexity of the Phoebus cartel's
actions (admittedly, it's a bigger picture than what we presented) -- but
there exists compelling evidence that the cartel exercised planned
obsolescence (we understand planned obsolescence to be when the "lifespan of a
product is rendered artificially short by design"). Pre-1900, bulbs had
lifespans of 1,200-2,500 hours; the cartel set bulbs at 1,000 hours -- even
when GE (a member of the cartel) had access to modern tungsten filament
technology that could've increased the output of bulbs without so aggressively
compromising lifespan. While, as you said, the cartel's motivation was to
standardize the haphazard market, the byproduct of this was an overly-
assertive cap on longevity."

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nickhalfasleep
Many possible reasons.

A crude bulb with a thick filament will last longer, as the current per unit
area goes down. A thicker filament would of course drastically increase the
life.

And reduce the voltage by 10%, an incandescent bulb will last 10x longer. With
Tungsten the usual failure mode is excited evaporated material cooling and
ending up on the cool bulb wall, this is the "blackening" you see on the
bottoms of bulbs.

Tungsten is a pretty amazing material, but will wear down over time.

------
k1t
Related reading about planned obsolescence:

[http://www.hugtherhino.com/2013/04/planned-obsolescence-
dark...](http://www.hugtherhino.com/2013/04/planned-obsolescence-dark-history-
of.html)

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saalweachter
Is the Centennial Light actually superior to the classic light bulb?

The article states that the filament is 8 times thicker -- using 64 times more
material -- and only runs at 4 Watts. So to match the standard 100 Watt bulb,
you'd need 25 Centennial Lights, for a total of 1600 times more material.

Meanwhile, it's burned for 113 years, about 990 times the standard bulb's 1000
hour lifespan. 990 times better using 1600 times more material; should I be
impressed?

~~~
techrat
>should I be impressed?

Not really. Run a 100 watt lightbulb dimmed down to the brightness of a 1 watt
bulb and it will also likely run for 100 years.

~~~
smoyer
Especially if you don't switch it on and off ... they've got that bulb on a
UPS now so that it doesn't experience cooling/heating cycles which are what
kill (or at least finally kill) most incandescent bulbs.

As an aside, it's my experience that what kills most LED bulbs is transients
that fry their control circuits. Has anyone else noticed this?

~~~
zAy0LfpBZLC8mAC
What tends to kill incandescents is the non-uniform thinning of the tungsten
wire due to tungsten evaporating, which causes the thinner parts to heat up
more, combined with tungsten's positive temperature coefficient, which causes
a current rush on power-up when the filament is cold, which causes the weak
spots to heat up particularly rapidly and potentially higher that they would
if the surrounding wire was hot and thus had higher resistance (a cold
tungsten filament has about 1/15th the resistance compared to when it's
glowing hot).

Transients certainly are one problem for LEDs if the power filtering is bad,
another is (lack of) cooling - while LEDs produce much less heat, they also
need to stay much, much cooler: A tungsten filament is fine at 2400 °C, an LED
die should not get much hotter than 100 °C, preferably less than that, and
most fixtures are not particularly good at getting rid of heat.

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LeoPanthera
See also, the Oxford Electric Bell:

[https://en.wikipedia.org/wiki/Oxford_Electric_Bell](https://en.wikipedia.org/wiki/Oxford_Electric_Bell)

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shirro
The light that burns twice as bright burns half as long.

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rsingel
You mean Byron the bulb? [http://lukedanger.blogspot.com/2009/02/story-of-
byron-bulb.h...](http://lukedanger.blogspot.com/2009/02/story-of-byron-
bulb.html)

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acd
The light bulb conspiracy is a movie about the subject of planned
obsolescence.

------
Kenji
"They Don’t Make ‘Em Like They Used To" Wrong. The explanation why the bulb
still holds is very simple. By turning it off and on again, the tungsten
contracts and expands. That is why light bulbs break after a certain amount of
time. If you keep the bulb lit or turned off, it won't break. In this case,
the bulb was lit with the exception of very few power outages.

Also mentioned in the article: "Katz also adds that the bulb’s age could be,
in part, contributed to the fact that it hasn’t been turned off and on a whole
lot -- a process which is more exhausting on a bulb than letting it run
continuously (the filament needs to reheat itself, much like a car’s engine)."

~~~
coryrc
Not so much; it's operating far under the level of light it could put out and
at atrocious efficiency. As said in the article: "Modern bulbs, she explains,
use thinner tungsten filaments that put out more light (40 to 200 watts) burn
hotter, and are therefore taxed more rigorously than older bulbs like the
Shelby"

With semiconductors, the rule of thumb is an increase of 10 Kelvin halves the
lifetime of the part. Considering this bulb is running several hundred Kelvin
below modern bulbs, it isn't surprising it lasts. Run a modern 60W lightbulb
at 30Vac and it'll last just as long too, but put out so little light as to be
near useless (like this bulb).

~~~
jloughry
If you're at all interested in this topic, I can't recommend highly enough a
little book by Tony Kordyban, _Hot Air Rises and Heat Sinks: Everything You
Know About Cooling Electronics Is Wrong_. (The sequel, _More Hot Air_ , is
good too). The author makes the case, in Chapter 30, that those numbers, which
came from MIL-HDBK-217, were pulled out of somebody's hat at a time when
semiconductor reliability rates were changing rapidly due to process
improvements, and probably don't have much validity any more. When actual
reliability rates were compared to prediction and measured temperatures, there
was no correlation.

These books are great.

Refs:

[1] Tony Kordyban. _Hot Air Rises and Heat Sinks_. New York: ASME Press, 1998.
ISBN 0-7918-0074-1

[2] ---. _More Hot Air_. New York: The American Society of Mechanical
Engineers, 2005. ISBN 0-7918-0223-X

