OT?: Lightbulb life, curiousity

[w_tom]

One factor that determines fluorescent lamp life expectancy
is, again, the filament. Fluorescent bulbs use low pressure
gas whose electrical properties change with contamination. As
the filament (at each end to start the bulb) vaporizes, it
contaminates the gas, thereby increasing startup voltage and
eventual bulb failure.

Another curious fact to extending (some) fluorescent bulb
life expectancy was to maintain a small current through
startup filaments. It was never explained in that paper why
such currents extend bulb life nor provided numbers to
demonstrate the effect.

Of course numbers change for different types of
fluorescent. Even though fluorescent bulbs were developed
before incandescent bulbs, the science inside a fluorescent
bulb is significantly more complex. Once tried to apply those
equations to a series of inert gas bulbs. Never did succeed.
But then even material used in the electrode causes changes to
the equations. Fluorescent bulbs are significantly more
complex.

Mel wrote:

Well,plenty of replies for incandescent bulbs... any replies for compact
flouresents? I know that I shoulden't be putting a flouresent lamp in
the toilets or cupboards, but what about tha hall? the bathroom with a
big family? I hear the "15 minute" rule regularily, but why 15 minutes
and what are the mechanism that reduce life? And I have also heard that
handeling the glass part will reduce the number of cycles before the
lamp dies... but why?

Mel

 

[w_tom]

Early designs did this 'keep lamp warm' so that the initial
power on current (on the order of seven times normal current)
was not so destructive to transistors that controlled the
bulb. A warmer bulb does not have the larger power on current
that would harm a driver transistor.

"Michael A. Terrell" wrote:

Early mainframe computers had hundreds or even thousands of small
incandescent lamps on the control panel. They used a DC voltage and a
diode in a "Keep alive" circuit that kept the lamps warm, but not enough
to give visible light in a normally light room. It extended the life of
the lamps quit a bit.

 

[Don Klipstein]

In article <429b2868$0$7008$636a15ce@news.free.fr>, Mel wrote:

Well,plenty of replies for incandescent bulbs... any replies for compact
flouresents? I know that I shoulden't be putting a flouresent lamp in
the toilets or cupboards, but what about tha hall? the bathroom with a
big family? I hear the "15 minute" rule regularily, but why 15 minutes
and what are the mechanism that reduce life?

There is no one-size-fits-all rule here as in how many minutes does a
compact fluorescent have to stay off or else it would have been more
economical to leave it on.

For one reason, different wattages cost different amounts per minute to
operate, while the cost of the lamp does not vary much with wattage.

Also, some suffer more damage from starting than others.

As for why damage from starting? When the filaments (electrodes) are
not at normal running temperature, the emissive material on them is not
working fully. That results in a higher electric field (voltage gradient)
around the filaments when they are working as cathodes, and positive ions
will bombard the filaments with greater force than normal - and dislodge
atoms of the coating material.

Some are true instant start, which has the lamp operating before the
filaments are warmed up. The lamp may be slightly dimmer while the
filaments are warming up due to higher voltage drop until the
filaments are supporting a "thermionic arc". Some are similar to what is
called "rapid start" with standard fluorescents in the USA, where the lamp
starts glowing while the filaments are being warmed up, but the lamp is
fully on when the filaments get close to normal operating temperature.
Some are "programmed start", where the arc is struck after the filaments
are warmed up. Some have glow switch starting, and usually blink a few
times while starting.
Glow switch ones are the worst for a large number of starts, instant
start is second worst, and program start is the best in terms of damage to
a fluorescent lamp due to starting.

And I have also heard that handeling the glass part will reduce the
number of cycles before the lamp dies... but why?

I have not heard that one. The closest to that I heard is that halogen
bulbs do not like skin oil, salts, ash, alkalis, etc. The compact quartz
bulb/capsule gets extremely hot and is under high stress from high
pressure of the fill gas. Salts and alkalis (including from ash) leach
into quartz at that temperature, causing weak spots and/or stressed spots.

- Don Klipstein (don@misty.com)

 

[Don Klipstein]

In article <je1n915720eure32324u59dcu9h92d0mq7@4ax.com>, John Fields wrote:

On Mon, 30 May 2005 21:10:07 +0000 (UTC), don@manx.misty.com (Don
Klipstein) wrote:

In article <fvvh915gikn23bn3ma0ufm33jhf2chlmh3@4ax.com>, John Fields wrote:
On Sat, 28 May 2005 19:18:57 -0400, w_tom <w_tom1@hotmail.com> wrote:

So, if the lamp were to be operated continuously, the total number of
lamp-on hours would be greater than if the lamp were operated
intermittently.

Not by much.

---
Agreed, but the point wasn't about the difference in the length of the
lifetimes, it was that there would have been some life left in the
filament had it not been switched off and then on for the last time.
---

When a filament develops a neck that cannot survive a cold
start, the neck is suffering extra fast evaporation when running due to it
being hotter than the rest of the filament even in steady operation. This
ill state is accelerating at a rate that increases worse than
exponentially. The filament's hours are already numbered.

---
They were from the very first time it was switched on!
---

One possible significant exception: Halogen lamps, where chemical
processes can cause necks at the end of the filament, where they only
have excessive temperature while the rest of the filament is warming up
and not yet reached full resistance.

---
I don't understand that since if they got hotter faster they'd enter
the halogen cycle more quickly and local boil-off would be prevented.

The halogen cycle does not prevent evaporation - it returns evaporated
tungsten to the filament, and does not do an especially good job at
returning it where it is most needed.

The main reason that halogen lamps last longer than non-halogens with
the same filament temperature is that in halogens, the fill gas pressure
is much higher. This slows evaporation of the filament. The small size,
thicker walls and higher strength of the quartz (or specialized glass in
many cases) bulb/capsule permit a much higher fill gas pressure.
The halogen cycle does achieve some life extension, but not a whole lot
because the halogen cycle is not good at depositing more tungsten where it
is needed most. One thing the halogen cycle is needed for is keeping the
inner surface of the wall/capsule clean of tungsten - with the small area,
that surface would otherwise blacken quickly.
Another factor that many (but not all) halogen lamps benefit from: With
the small size of the bulb/capsule and higher cost, the cost does not get
much worse from using krypton instead of argon as a main fill gas
ingredient.

OTOH, since the lead wires are very low R and in intimate thermal
contact with the ends of the filament they may be acting like heat
sinks and keeping the temperature of the ends of the filament lower
than the rest of it until it warms them up. If that's the case, it
may be that the delay of the ends of the filament in entering the
halogen cycle causes excessive boil-off until it gets hot enough to
start working right.

What do you think?

I think that a neck near the end of the filament, due to less mass,
warms up faster than the rest of the filament and can overshoot in
temperature when the rest of the filament is not yet warmed up. And
heatsinking is just enough to have the temperature a little lower than
that of the rest of the filament in steady operation. That's what I think
happens.

- Don Klipstein (don@misty.com)

 

[Don Klipstein]

In article <429B9F11.772FD450@hotmail.com>, w_tom wrote:

One factor that determines fluorescent lamp life expectancy
is, again, the filament. Fluorescent bulbs use low pressure
gas whose electrical properties change with contamination. As
the filament (at each end to start the bulb) vaporizes, it
contaminates the gas, thereby increasing startup voltage and
eventual bulb failure.

Filament material does not contaminate the gas - it condenses on the
inner surface of the bulb.

Another curious fact to extending (some) fluorescent bulb
life expectancy was to maintain a small current through
startup filaments. It was never explained in that paper why
such currents extend bulb life nor provided numbers to
demonstrate the effect.

Can you cite the paper that claims this happens even without explaining
why?

In fluorescent lamps, the usual failure is not from the filaments
breaking, but from the emissive coating being worn away. Some
fluorescents (main example - rapid start) have power applied to the
filaments during operation and I have heard a couple times that some of
these have reduced life if the filament power is removed during operation,
but I have not heard of fluorescents lasting longer if the filaments are
kept warm while they are off.

- Don Klipstein (don@misty.com)

 

[w_tom]

This claim that a filament with a few milliamps of current
through it would last longer has always struck me odd. I
mention it because it came from a reputable source, because
details were not provided, and because I always remained
curious. Unfortunately I believe it was a manufacturer's
paper that has since been gone for a few decades; don't
remember the source. The paper noted factors that effective
lamp life expectancy. It defined that filament current in
terms of single digit voltage - too much or too little caused
less improvement. I mention it, in part, that others may
provide additional information. This puzzling nature for some
fluorescents has always left me curious.

Basic equations for physics on designing fluorescant lamps
noted that gas contamination contributes to bulb failure;
changed constants in that equation. BTW, one needs a library
well predating WWII to find these gaseous physics books. We
demonstrated this electrode contamination when designing a
custom fixture to light multiple bulbs using different inert
gases. Too much current caused electrodes (or filament
depending on bulb) to contaiminate the gas thereby changing
its electrical characteristics enough to become bulb
failure. Of course "emissive coating being worn away" would
also be same as gas contamination. Another factor that
changes the equation is gas pressure. If that coating goes
somewhere, does it change tube pressure? As noted earlier,
even the equations are quite complex. Never did get the
equations to work. Ended up resorting to a 'trial and error'
method.

Don Klipstein wrote:

Filament material does not contaminate the gas - it condenses on the
inner surface of the bulb.

Another curious fact to extending (some) fluorescent bulb
life expectancy was to maintain a small current through
startup filaments. It was never explained in that paper why
such currents extend bulb life nor provided numbers to
demonstrate the effect.

Can you cite the paper that claims this happens even without
explaining why?

In fluorescent lamps, the usual failure is not from the filaments
breaking, but from the emissive coating being worn away. Some
fluorescents (main example - rapid start) have power applied to the
filaments during operation and I have heard a couple times that some
of these have reduced life if the filament power is removed during
operation, but I have not heard of fluorescents lasting longer if
the filaments are kept warm while they are off.

- Don Klipstein (don@misty.com)

 

[Watson A.Name - \"Watt Su]

"Mel" <melodie@pasdespam.chezmoi> wrote in message
news:429b2868$0$7008$636a15ce@news.free.fr...
Well,plenty of replies for incandescent bulbs... any replies for compact
flouresents? I know that I shoulden't be putting a flouresent lamp in


Flourescents? If you expect answers, try spelling it fluorescents.

the toilets or cupboards, but what about tha hall? the bathroom with a
big family? I hear the "15 minute" rule regularily, but why 15 minutes
and what are the mechanism that reduce life? And I have also heard that
handeling the glass part will reduce the number of cycles before the
lamp dies... but why?



Mel

see.my.sig.4.addr@nowhere.com.invalid a écrit :

I don't know if these are the right places to ask this, but it's the
best
I could find on the server. Sorry if it's OT:

I was just thinking today what influences a lightbulb's life more.
They're rated in hours, but I know for a fact they burn out sooner if
you
turn them on and off more. Kinda like a HDD, but to way less extent.
But, how far does that extend.. a HDD I've heard lasts longest if it's
on/off 1x/day, assuming you're going to sleep and/or not use it for at
least 10-12hrs. I wonder how it works for lightbulbs, say 40watt. I
assume it would matter more with more wattage because there'd be more
diff. between hot and cold states. So, if you're going to leave the
light
off for 2hrs, should you not and leave it on instead? You know,
what's
the min. time you'd have to leave it off for before you actually cost
life
due to on/off even though you're saving hrs. Hey, you think about
these
types of thing while you're sitting on the can! So anybody know?
--
_____________________________________________________
For email response, or CC, please
mailto:see.my.sig.4.addr(at)bigfoot.com.
Yeah, it's really a real address

 

[Watson A.Name - \"Watt Su]

"w_tom" <w_tom1@hotmail.com> wrote in message
news:429BA908.2BCF25BC@hotmail.com...

[snip]

My observation is that most bulb failures occur during powerup; whether
or not this is due to the powerup is entirely another matter. The most
probable reason that these failures occur during powerup is that this is
the time when more stress is put on the filament.

 

[Mel]

Watson A.Name - "Watt Sun, the Dark Remover" a écrit :

"Mel" <melodie@pasdespam.chezmoi> wrote in message
news:429b2868$0$7008$636a15ce@news.free.fr...
Well,plenty of replies for incandescent bulbs... any replies for compact
flouresents? I know that I shoulden't be putting a flouresent lamp in


Flourescents? If you expect answers, try spelling it fluorescents.

Sorry, it slipped through.... but not everyone is a native English
speaker here, and spelling errors are bound to happen - my spell checker
didn't detect the error either, and google didn't really mind either (13
300 hits with the wrong spelling - I'm not the only one!). Doesn't seem
to have bothered anyone else....



Mel

the toilets or cupboards, but what about tha hall? the bathroom with a
big family? I hear the "15 minute" rule regularily, but why 15 minutes
and what are the mechanism that reduce life? And I have also heard that
handeling the glass part will reduce the number of cycles before the
lamp dies... but why?



Mel

see.my.sig.4.addr@nowhere.com.invalid a écrit :

I don't know if these are the right places to ask this, but it's the

best

I could find on the server. Sorry if it's OT:

I was just thinking today what influences a lightbulb's life more.
They're rated in hours, but I know for a fact they burn out sooner if

you

turn them on and off more. Kinda like a HDD, but to way less extent.
But, how far does that extend.. a HDD I've heard lasts longest if it's
on/off 1x/day, assuming you're going to sleep and/or not use it for at
least 10-12hrs. I wonder how it works for lightbulbs, say 40watt. I
assume it would matter more with more wattage because there'd be more
diff. between hot and cold states. So, if you're going to leave the

light

off for 2hrs, should you not and leave it on instead? You know,

what's

the min. time you'd have to leave it off for before you actually cost

life

due to on/off even though you're saving hrs. Hey, you think about

these

types of thing while you're sitting on the can! So anybody know?
--
_____________________________________________________
For email response, or CC, please

mailto:see.my.sig.4.addr(at)bigfoot.com.

Yeah, it's really a real address

 

[Don Klipstein]

In article <429BA908.2BCF25BC@hotmail.com>, w_tom wrote:

This claim that a filament with a few milliamps of current
through it would last longer has always struck me odd. I
mention it because it came from a reputable source, because
details were not provided, and because I always remained
curious. Unfortunately I believe it was a manufacturer's
paper that has since been gone for a few decades; don't
remember the source. The paper noted factors that effective
lamp life expectancy. It defined that filament current in
terms of single digit voltage - too much or too little caused
less improvement. I mention it, in part, that others may
provide additional information. This puzzling nature for some
fluorescents has always left me curious.

Basic equations for physics on designing fluorescant lamps
noted that gas contamination contributes to bulb failure;
changed constants in that equation. BTW, one needs a library
well predating WWII to find these gaseous physics books. We
demonstrated this electrode contamination when designing a
custom fixture to light multiple bulbs using different inert
gases. Too much current caused electrodes (or filament
depending on bulb) to contaiminate the gas thereby changing
its electrical characteristics enough to become bulb
failure. Of course "emissive coating being worn away" would
also be same as gas contamination. Another factor that
changes the equation is gas pressure. If that coating goes
somewhere, does it change tube pressure?

It does not significantly even temporarily, let alone permanenetly,
since the vapors of the coating don't stay vaporized long but condense on
the inner surface of the bulb rather quickly.

As for gaseous contaminants - usually things work more the other way
around. Fluorescent lamps tend to get those during manufacture or (more
likely in the case of lower quality lamps) when the lamp is first
operated, and operation after that tends to have gaseous contaminants
removed by chemically reacting with the filaments more than add more
contaminants.

One thing that happens in a few discharge lamps (mostly other than
fluorescent) is with a neon-argon mixture that is mostly neon - often
99.5% neon .5% argon: Argon ions dig their way into the inner surface of
the bulb and the argon gets stuck there, resulting in a loss of argon.
Starting becomes more difficult when this happens. I have heard of this
being a problem with some low pressure sodium lamps.

But when a neon glow lamp running from 120V AC starts flickering, this
is not the problem since the ones that flicker when they get old use pure
neon, and ones with neon-argon mixture tend to just fade from blackening
of the bulb. Ones with pure neon I believe start this flickering
business when a coating on the electrodes being worn away while ones with
a bit of argon can keep glowing steadily although dimmed by bulb
blackening.

- Don Klipstein (don@misty.com)

 

[w_tom]

If speculating, then at least put some numbers to that
'massive stress'. Filament must be severely damaged for that
gentle 'power-on' stress to break it. Often that stress is so
minimal that the filament instead fails by vaporizing the
little that remains at the hot spot. A far more severe stress
is people walking on the floor above.

Filament gets real hot; therefore it must be high stress?
Without numbers to define stress, then stress is only wild
speculation. The point of my initial post that resulted in so
much emotion: They did not know. They speculated. They did
not first consult industry sources, numbers, or citations.
They just speculated. Speculation creates junk science
reasoning.

Once the filament is so badly damaged, then dark spots
appear inside the glass envelope. Then either the bulb fails
on power on OR fails during operation some hours later. My
last bulb failed some hour after power on. Most never notice
failure during operation but always notice the failure on
power on. Just another reason why observation is not a valid
fact. But again, damage that causes failure is defined by ...
hours of operation.

Numbers, equations, citations, etc were provided
previously. If you think power on causes so much stress,
well, where are both numbers and citations? Wild speculation
and no numbers are symptoms of junk science. Please don't
make that mistake. Enough junk science reasoning (followed by
emotional outbursts when bluntly confronted) has already been
posted in this discussion.

You are assuming the seven times or tens times current on
power up is destructive. This assumption is answered in
another post.

Fred McGalliard wrote:

Odd. I thought a filament turn on cycle included a nasty inrush
surge, followed by rapid heating, heat shock to the glass elements,
high current stress to any narrow spots or areas where heat flow
is restricted by element positioning, etc. That's why most failures
we observe (in the mostly intermittent operations we see in our
homes) occur during the turn on transition, not during steady state
operation.

 

[w_tom]

Filament temperature determines vaporization. When current
is high, filament is cool.

What is the maximum current in a typical 20 amp wire. Maybe
300 amps? Many will then assume 300 amps will always be
destructive. Wrong. That same wire can conduct thousands of
amps if only for a short period - without any damage. Same is
true of that seven or ten times current during startup
illumination. Large current is quite short. Filament is cool
during that short period. Therefore no significant filament
vaporization during that high current period.

Fred Stevens wrote:

My understanding is that current surge is a main contributing factor
for lamps failing. Cold resistance is lower than warm resistance, so
bulbs often fail when switched on. This is one of the main reasons why
airfield lighting systems use constant current sources with slow
current ramps for switch on.

Fred.

 

[Dan Bloomquist]

w_tom wrote:

Filament temperature determines vaporization. When current
is high, filament is cool.

What is the maximum current in a typical 20 amp wire. Maybe
300 amps? Many will then assume 300 amps will always be
destructive. Wrong. That same wire can conduct thousands of
amps if only for a short period - without any damage. Same is
true of that seven or ten times current during startup
illumination. Large current is quite short. Filament is cool
during that short period. Therefore no significant filament
vaporization during that high current period.

But not at a weak spot. There the resistance is higher. There you have
light bursting from the wire before the rest of the filament comes up to
temperature.

Best, Dan.

 

[John Fields]

On Tue, 31 May 2005 23:28:41 -0400, w_tom <w_tom1@hotmail.com> wrote:

If speculating, then at least put some numbers to that
'massive stress'. Filament must be severely damaged for that
gentle 'power-on' stress to break it. Often that stress is so
minimal that the filament instead fails by vaporizing the
little that remains at the hot spot. A far more severe stress
is people walking on the floor above.

---
PKB. Where are the numbers? How many amps/second on turnon? at what
conduction angle? What does the resistance of the hot spot have to be
for that vaporization on turn-on to occur? What diameter does that
resistance correspond to? At what tensile (or shear) strength will
the filament part? How severe is the stress caused by the foosteps
overhead? How hard do the footsteps have to hit the floor for the
filament to part?
---

Filament gets real hot; therefore it must be high stress?
Without numbers to define stress, then stress is only wild
speculation. The point of my initial post that resulted in so
much emotion: They did not know. They speculated. They did
not first consult industry sources, numbers, or citations.
They just speculated. Speculation creates junk science
reasoning.

---
So post some numbers to support _your_ claims, above.
---

Once the filament is so badly damaged, then dark spots
appear inside the glass envelope. Then either the bulb fails
on power on OR fails during operation some hours later. My
last bulb failed some hour after power on. Most never notice
failure during operation but always notice the failure on
power on. Just another reason why observation is not a valid
fact. But again, damage that causes failure is defined by ...
hours of operation.

---
That's foolish reasoning in that if a lamp blows when you turn it on
you're immediately mad aware that the lamp has failed. In the other
case you won't know immediately unless you're in the room when it
happens, but if you came back later and the lamp has blown you'll
notice it and, since you'll know that it didn't let go when you turned
it on it must have failed when it was operating. Duh.
---

Numbers, equations, citations, etc were provided
previously. If you think power on causes so much stress,
well, where are both numbers and citations?

---
If you think it doesn't, where is your supporting evidence?
---

Wild speculation
and no numbers are symptoms of junk science. Please don't
make that mistake. Enough junk science reasoning (followed by
emotional outbursts when bluntly confronted) has already been
posted in this discussion.

---
And continues to be. Mostly by you.
---

You are assuming the seven times or tens times current on
power up is destructive. This assumption is answered in
another post.

---
I don't recall seeing it. Would you go over it again, please, with
some numbers to back up your position?

Thank you,


--
John Fields
Professional Circuit Designer

 

[John Fields]

On Tue, 31 May 2005 23:41:59 -0400, w_tom <w_tom1@hotmail.com> wrote:

Filament temperature determines vaporization. When current
is high, filament is cool.

What is the maximum current in a typical 20 amp wire. Maybe
300 amps? Many will then assume 300 amps will always be
destructive. Wrong. That same wire can conduct thousands of
amps if only for a short period - without any damage. Same is
true of that seven or ten times current during startup
illumination. Large current is quite short. Filament is cool
during that short period. Therefore no significant filament
vaporization during that high current period.

---
How about some numbers?

Length / Resistance of the wire? Temperature rise as a function of
current? Thousands of amps for how long? How short is a short
period? Mechanical forces on the filament during a cold start? Time
constant of the filament?

--
John Fields
Professional Circuit Designer

 

[w_tom]

By weak spot, I assume you meant the hot spot. The hot spot
is created by vaporization. Once the hot spot has formed,
then a bulb is doomed. As noted earlier, bulb fails either in
normal operation or in power on. The gentle force of power-on
can cause a bulb in its last 10 hours of operation to fail
during the power on. Indication that the bulb will soon fail
- that excessive filament damage has already occured - is
blackened deposits inside the glass envelope. IOW failure
even during power on is due to damage created by hours of
operation.

Many, such as some early posters, saw a bulb fail during
power on and then assumed power on was destructive. Industry
research (complete with pictures that showed the hot spot as
darker) explain why a bulb fails either while powered or
during power on. Failure is created by hours of operation;
damage due to filament vaporization.

Light bulb failure demonstrates what is required to create a
fact. A fact is explained theoretically AND is observed
experimentally. Both conditions are required. Those who saw a
bulb flash during power on only had experimental
observations. Therefore they speculated. When underlying
principles (filament vaporization) is included, then
sufficient information exists to build a fact. My initial
post criticized others who somehow knew only because they had
observed a bulb fail on power on. They were performing
classic junk science reasoning. They were violating basic
science principles as even taught in junior high school. They
did not first learn the principles and numbers of light bulb
operation.

Why would that seven or ten times current cause a bulb
failure? The filament has been so thinned in one spot by
hours of operation that a doomed incandescent bulb burns out -
either during power on or some hours later.

Dan Bloomquist wrote:

But not at a weak spot. There the resistance is higher. There you have
light bursting from the wire before the rest of the filament comes up to
temperature.

 

[tesseract]

Mick Sharpe writes:

"When you switch on an incandescent lamp, some the tungsten that the
filament
is made of evaporates and remains in a gaseous state until the lamp is
switched off, when the tungsten gas will condense out. Unfortunately,
since
the envelope of the bulb offers a much greater surface area than the
filament, the gas condenses onto the bulb, where it remains. As you
switch
the lamp on and off, metal slowly migrates from the filament to the
bulb
envelope, turning it black. Eventually, the filament becomes too thin
to
accomodate the supplied current and the lamp 'blows'. "

Quite true, and there are additional factors. Heating and cooling add
stress. If the
filament is a coil, it is an inductor, and AC self inductance will
cause it to flex, it possibly
being less flexible when it is cool. There may be additional factors
yet.
Fluorescent bulbs are now fairly cheap, and power leds are just over
the horizon,
available but pricey. Both convert more of the electrical energy into
light rather than heat.
I know that some exceptional incandescents that were never turned off
lasted over twenty years.

tesseract

 

[spudnuty]

I've actually have a carbon filament bulb that I got from Kennedy
Webster in Chicago. Its been burning every night from 6PM to 7PM for
about 7 years now in my front hall . It burns very orange perhaps
~22,000ş K and it is VERY sensitive to shock and vibration even when
they're cold. These are often used in antique fixtures and it's
suprised me how long it's lasted. I always thought tungsten was
superior.
They're most famously used in the Monadnock building in Chicago.
Richard

 

w_tom wrote:

Being politically correct is akin to lying for a self
serving gain. I am not politically correct; have no interest
in being so corrupt. Mick Sharpe obviously was not insulted
if the objective is accurate facts.

Fact remains that incandescent life expectancy is a function
of filament temperature (voltage) and other environmental
factors such as mechanical shock when filament is hot. This
assumes a statistically average bulb; making manufacturing
defects (ie hot spots created by a production defect)
irrelevant. The underlying point is why some promote myths
not based upon science.

Again the lessons of history are cited. Many even believe
lying politicians who don't provide numbers - be it Saddam's
weapons of mass destruction, or people of German ancestry
persecuted in Checkoslavakia. Either way, its called
propaganda. How do politicians, et al get away with lies? No
numbers. No responsible sources. And people who just blindly
believe these lies because it is the first thing they are
told. Beliefs based upon emotion rather than first demanding
supporting numbers and facts. Again, it's called
propaganda. A glaring symptom of propaganda is no numbers. If
they provided numbers, then their lies could be easily
exposed.

No insults posted or intended. Just a blunt fact about
light bulb life expectancy and similar examples from history.

And where are your numbers ?

troll ?
GG

 

[tesseract]

I wish that people who require numbers of others would post a few of
their own.
A little tolerance of others and a less superior tone would be
appreciated.
Try posting political posts on soc.politics, where they belong.
Remember that most come on groups for an interesting discussion, which
requires
differing opinions, and not to function as the therapist for someone
wishing to make some
obscure correlation between filament life and the truthfulness of
politicians.
Let's try for more light and less heat.

tesseract