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Posted by CL (dnoyeB) Gilbert on July 26, 2005, 5:25 pm
Chris Lewis wrote:
show/hide quoted text
> Yeah, I know, not this topic again... But this is getting ridiculous.
>
> I have a string of about 6 pot fixtures in the basement with BR30
> bulbs. The fixtures are switched by a pair of 3 way switches.
> The fixtures are open to the air - the ceiling hasn't been
> drywalled (yet).
>
> The bulbs are burning out at a very high rate. Within a week
> of getting them all working again, at least one goes out, within
> another month, usually all of them are dead.
>
> As far as I can remember, these have all been Sylvanias, some
> "extended lifetime" (hah!).
>
> Most of the time, a bulb expires when we "flick" (as opposed to
> "sloowwly presssss" ;-) one of the threeways. The threeway switches
> are relatively newish decora type switches. Probably cheapies -
> I'll bet they bounce a lot.
>
> I'm looking for real-world experience here - has anybody solved
> lamp burnouts like this by replacing the switches? Are there
> line filters for this sort of purpose?
>
> I want to exhaust those possibilities before going on an expensive
> quest for more expensive bulbs.
you can try installing a dialed dimmer switch. or see if you can find
any of those devices that go in the socket that are supposed to extend
the life of the bulb, not sure what they do.
could it be the room temperature is too low? Soft starting of lights
definitely extends the life.
--
Respectfully,
CL Gilbert
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Posted by Don Klipstein on July 27, 2005, 1:27 am
in part:
show/hide quoted text
>you can try installing a dialed dimmer switch. or see if you can find
>any of those devices that go in the socket that are supposed to extend
>the life of the bulb, not sure what they do.
>could it be the room temperature is too low? Soft starting of lights
>definitely extends the life.
Usually not much (there are some exceptions), despite lightbulbs
typically blowing during a cold start.
What usually happens is that cold starts do surprisingly little damage
to the filament, while a filament that is approaching end-of-life (due
mainly to operating hours and filament temperature during steady
operation) becomes unable to survive a cold start a little before becoming
unable to survive steady operation.
A filament that has suffered uneven evaporation to the extent to become
unable to survive a cold start is already in bad shape, and this condition
is accelerating at a rate that increases worse than exponentially while
the filament is running.
Now a bit of specific data: I actually got one of those soft-starting
"buttons" to attach to the bottom of a lightbulb to supposedly double its
life. I managed to get an indirect reading of voltage drop across the
"button" and the lightbulb while the "button" was in place and fully
warmed up, and it turns out the "button" dropped enough voltage to dim the
lightbulb enough to extend its life 50%. Also: Using the usual rules of
lightbulb performance as a function of voltage, light output went down 11%
while current consumption (and power consumption, counting watts
dissipated in lightbulb and button combined) went down 1.7%.
- Don Klipstein (don@misty.com)
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Posted by CL (dnoyeB) Gilbert on July 27, 2005, 12:06 am
Don Klipstein wrote:
show/hide quoted text
> in part:
>
>
>>you can try installing a dialed dimmer switch. or see if you can find
>>any of those devices that go in the socket that are supposed to extend
>>the life of the bulb, not sure what they do.
>>could it be the room temperature is too low? Soft starting of lights
>>definitely extends the life.
>
>
> Usually not much (there are some exceptions), despite lightbulbs
> typically blowing during a cold start.
>
> What usually happens is that cold starts do surprisingly little damage
> to the filament, while a filament that is approaching end-of-life (due
> mainly to operating hours and filament temperature during steady
> operation) becomes unable to survive a cold start a little before becoming
> unable to survive steady operation.
>
> A filament that has suffered uneven evaporation to the extent to become
> unable to survive a cold start is already in bad shape, and this condition
> is accelerating at a rate that increases worse than exponentially while
> the filament is running.
>
yes. Its kind of playing a game. Like using something thats broken,
but using it very gently so as to keep using it...
show/hide quoted text
> Now a bit of specific data: I actually got one of those soft-starting
> "buttons" to attach to the bottom of a lightbulb to supposedly double its
> life. I managed to get an indirect reading of voltage drop across the
> "button" and the lightbulb while the "button" was in place and fully
> warmed up, and it turns out the "button" dropped enough voltage to dim the
> lightbulb enough to extend its life 50%. Also: Using the usual rules of
> lightbulb performance as a function of voltage, light output went down 11%
> while current consumption (and power consumption, counting watts
> dissipated in lightbulb and button combined) went down 1.7%.
>
> - Don Klipstein (don@misty.com)
Nice. We do the same thing to car headlamps when possible.
--
Respectfully,
CL Gilbert
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Posted by Phil Munro on July 27, 2005, 2:40 pm
Don Klipstein wrote:
show/hide quoted text
> in part:
>
>>you can try installing a dialed dimmer switch. or see if you can find
>>any of those devices that go in the socket that are supposed to extend
>>the life of the bulb, not sure what they do.
>>could it be the room temperature is too low? Soft starting of lights
>>definitely extends the life.
>
> Usually not much (there are some exceptions), despite lightbulbs
> typically blowing during a cold start.
>
> What usually happens is that cold starts do surprisingly little damage
> to the filament, while a filament that is approaching end-of-life (due
> mainly to operating hours and filament temperature during steady
> operation) becomes unable to survive a cold start a little before becoming
> unable to survive steady operation.
>
> A filament that has suffered uneven evaporation to the extent to become
> unable to survive a cold start is already in bad shape, and this condition
> is accelerating at a rate that increases worse than exponentially while
> the filament is running.
>
> Now a bit of specific data: I actually got one of those soft-starting
> "buttons" to attach to the bottom of a lightbulb to supposedly double its
> life. I managed to get an indirect reading of voltage drop across the
> "button" and the lightbulb while the "button" was in place and fully
> warmed up, and it turns out the "button" dropped enough voltage to dim the
> lightbulb enough to extend its life 50%. Also: Using the usual rules of
> lightbulb performance as a function of voltage, light output went down 11%
> while current consumption (and power consumption, counting watts
> dissipated in lightbulb and button combined) went down 1.7%.
>
> - Don Klipstein (don@misty.com)
Lots of nice info there. Thanks. I am wondering what the effective
voltage drop would be for a dimmer that is full on.
It has been my experience from work with tungsten heating coils in a
vacuum system that unused tungsten can be bent into small radius turns,
BUT, after it has been used into the dull red heat range the same wire
will break if that same bending is attempted. I guess it has to do
with annealed or not annealed and work hardening, but I can never
remember how that goes!
My point is that a USED bulb filament is mechanically fragile, AND
when standard service bulbs are turned on with a switch, there are
MECHANICAL forces due to the start up of magnetic/electric fields.
These mechanical forces on the filament may be demonstrated by the
ringing sound some filaments will make when a dimmer is set low. Sound
is due to a mechanical phenomenon, so that would mean the filament is
vibrating!
I continue to be convinced that using an up/down dimmer (one with no
abrupt on/off) slows down bulb burn out, and that mechanical actions
will also do it for bulbs. For example, rough service bulbs last longer
in mechanically rough service, and if we look at the guts of such bulbs,
we see extra filament supports which minimize vibration. --Phil
--
Phil Munro Dept of Electrical & Computer Engin
mailto:PcMunro@cc.ysu.edu Youngstown State University
Youngstown, Ohio 44555
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Posted by Doug Kanter on July 27, 2005, 6:52 pm
show/hide quoted text
> For example, rough service bulbs last longer
> in mechanically rough service, and if we look at the guts of such bulbs,
> we see extra filament supports which minimize vibration. --Phil
I've never found a rough service bulb whose light color wasn't ugly. I
wonder why?
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>
> I have a string of about 6 pot fixtures in the basement with BR30
> bulbs. The fixtures are switched by a pair of 3 way switches.
> The fixtures are open to the air - the ceiling hasn't been
> drywalled (yet).
>
> The bulbs are burning out at a very high rate. Within a week
> of getting them all working again, at least one goes out, within
> another month, usually all of them are dead.
>
> As far as I can remember, these have all been Sylvanias, some
> "extended lifetime" (hah!).
>
> Most of the time, a bulb expires when we "flick" (as opposed to
> "sloowwly presssss" ;-) one of the threeways. The threeway switches
> are relatively newish decora type switches. Probably cheapies -
> I'll bet they bounce a lot.
>
> I'm looking for real-world experience here - has anybody solved
> lamp burnouts like this by replacing the switches? Are there
> line filters for this sort of purpose?
>
> I want to exhaust those possibilities before going on an expensive
> quest for more expensive bulbs.