Rather dramatic incandescent bulb failure.

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I just went to turn on a light. The bulb emitted a bright blue flash,
and its glass envelope separated from the base, bounced off the rear
enclosure of the television and fell to the wooden floor.

Scared the bejeezus out of me. The only redeeming feature was that the
bulb didn't shatter.

After fifty years and a few, that's a new one on me.

Sylvia.

Re: Rather dramatic incandescent bulb failure.


We've had a few of those, last one the bulb exploded and sent glass over
three metres, the still flaming filament landed on a leather chair. The box
it came in said "Quality Checked". Hope the new high efficiency ones don't
go the same way.


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Re: Rather dramatic incandescent bulb failure.


On Mon, 17 May 2010 00:08:13 +0930, "M Phillips"

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The box passed all its tests.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: Rather dramatic incandescent bulb failure.


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Anyone know what the typical failure mode of a compact fluorescent is?
(I assume that's the intent of "high efficiency").

Sylvia.

Re: Rather dramatic incandescent bulb failure.


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**I've heard about capacitor failures. I've never experienced any. I've been
using CFLs for about 8 years. I presently have a couple of dozen around the
place. All are Philips branded lamps, except four PAR38 CFL floods (which
don't get used very much). Some are used from as little as 10 mins per day,
to more than 4-5 hours per day. The two failures I've had were:

* Possum sat/fell/brushed against one in the garage.
* I installed one into a portable 'touble light' and dropped it. A rock
penetrated the glass.

I am uncertain if an incandescent would have survived or not. I'm betting a
definite maybe.

I don't much care for the colour temperature of the cheap brands, nor, it
seems, their reliability. I've found the Philips lamps to have a pleasing
colour temperature and have, thus far, been utterly reliable.


--
Trevor Wilson
www.rageaudio.com.au



Re: Rather dramatic incandescent bulb failure.


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I've tended to opt for the higher colour temperature variants. OK, they
look rather blue in comparison with incandescents, but in reality they
are just a better white. One gets used to them, as well as having things
look blue when they are, rather than black.

Sylvia.


Re: Rather dramatic incandescent bulb failure.



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Would you like my Phillips CFL that failed to work from new then? I've had
dozens fail, including a few Phillips and many other brands. In fact I've
*never* had one last as long as claimed yet! (and very few are in enclosed
fittings either)

MrT.





Re: Rather dramatic incandescent bulb failure.


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Bad Caps are very common in many China made things around my place.
Here pictures of one of a few CFLs that spit the dummy on me:

http://i887.photobucket.com/albums/ac72/scarborofun/CFL/PICT6561_2.jpg
http://i887.photobucket.com/albums/ac72/scarborofun/CFL/PICT6565_2.jpg
http://i887.photobucket.com/albums/ac72/scarborofun/CFL/PICT6557.jpg
http://i887.photobucket.com/albums/ac72/scarborofun/CFL/PICT6563.jpg

Note that not only had the Cap a short but also the connections to the actual
tube where more than dodgy.

Tony

Re: Rather dramatic incandescent bulb failure.


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I wonder who it was decided that four diodes were optional. Looks like
three were simply ommited, and one was replaced by a link.

Sylvia.



Re: Rather dramatic incandescent bulb failure.


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Usually the tube fails, I have checked dozens of dead ones over the
past few years.  (Connect a normal tube to the terminals and it will
work.)

Havent seen any electronics failures, but in our case they all have
been operated inside ventilated equipment cabinets, the base to the
bottom.

Others have had other experiences however, judging by stories and pics
on some forums, though may have been used in hot areas, or sealed
fittings with nil ventilation. Under these circumstances, I see no
reason to doubt these reports considering some of the crap electronics
around, and the common failure of electrolytics in most applications.


I recall hearing years back about a mirabella brand bulb "exploding"
at switch on.  It might have been on a consumer affairs program (that
one on ABC years back probably), a current affairs type program or
similar.

No details were given of the exact failure other than "big bang and
bulb flew out of socket" or similar.


Another warning I read of a long time back was the use of certain
incandescent (maybe QH or back reflected varieties of floodlight bulbs
used) in shop window displays. They could shatter when they failed,
dumping red hot filament pieces over clothing or other flammable
display items beneath, starting a fire.




Re: Rather dramatic incandescent bulb failure.



"kreed"
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Usually the tube fails,

** Yep -  the filament at one end burns out and typically leaves a dark mark
on the glass.

This is a direct result of makers running the filaments very hot in an
attempt to get the lamp to produce full light output quickly even when the
ambient temp is close to 0 degrees C.

The other common failure is the glass tube cracking during handling as it is
impossible to install or remove a CFL in many light fittings without holding
onto the glass.

You don't get to see many failures that originate in the electronics because
the other failure modes come first  OR else the tube loses so much light
output is it no longer usable.

IME  lifespans for CFLs quoted on the packaging as being 10,000 or even
15,000 hours are purest fantasy.



.....  Phil






Re: Rather dramatic incandescent bulb failure.


On Mon, 17 May 2010 00:24:59 +1000, Sylvia Else

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I've had Mirabella bulbs that did that.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: Rather dramatic incandescent bulb failure.


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Mine was an Osram.

I'm a bit surprised, indeed somewhat concerned, that the circuit breaker
didn't trip. It's rated at 10A, but the individual lamp sockets won't
be. I'm wondering how I can safely test it.

Sylvia.

Re: Rather dramatic incandescent bulb failure.



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Classic ordinary light bulbs are fused, usually both leads to the filament
have fuses fitted.  If you still have the lamp you would see the fuses
welded into the wires on the inside of the glass filament holder.

So your 10A circuit breaker would not ber expected to trip as the lamp's
overcurrent was over way to soon to trip a thermal breaker.  

As for the lamp bulb jumping out of the base, was it a very old lamp?

Lots of thermal cycles possibly weakened the adhesove to the base.

As to failure mode of CFLs, I been using CFLs for a couple decades,
and ones I see fail simply go out, or fail to start.  Recently a matched
pair of supermarket CFLs in the same light fitting quit within days of
each othjer -- so I took the glass out of that ceiliung fitting to let
the replacements run cooler.

I think CFLs suffer from the heat buildup inside some types of fittings.

Grant.
--
http://bugs.id.au /

Re: Rather dramatic incandescent bulb failure.


wrote:
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In this instance, the power wires are intact from the filament, through
the glass seal, and about halfway towards the base - then they vanish -
both of them, at about the same point. I suppose the fuses could have
been fitted there, explaining why the wires terminate abruptly. When
whatever was there, be it ordinary wire, or fuse, evaporated, it would
have increased the pressure in the space between the seal and the base,
both through the evaporation, and heating of the air in there.

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Well, falling out, given that this was in a typical lamp holder
suspended from the ceiling.

No, it wasn't old at all.

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Perhaps, though it was a living room light, so I wouldn't expect it to
suffer high cycles before filament failure.

Sylvia.

Re: Rather dramatic incandescent bulb failure.



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wrote:
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Well that's where the fuses were, I remember them as being encapsulated,
but perhaps that's a feature on some brands only.  This is something I
explored a long time ago.

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Yes, any electric fireworks usually gives at least a pop, sometimes a
bang :)  The fuse is only a section (about one cm or 1/2") of smaller
gauge wire spot welded between the wire from the filament glass to the
wire from the lamp base.  Sometimes the fuse is encapsulated in a long
glass envelope, I don't think your lamp had the encapsulated sort.
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Funny, I visualised the lamp being closer to ground level, thinking
it dropped a small distance.  Dropping from the ceiling and no broken
glass is more amazing.
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Ah well, maybe the modern glues are less sticky?  Long time since I saw
an old globe go pop, CFLs fail without fanfare here.

Grant.
--
http://bugs.id.au /

Re: Rather dramatic incandescent bulb failure.



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Well, not actually from ceiling height, because it was suspended. But I
suspect that television saved the day, because the bounce off the rear
housing probably caused the bulb to turn over so that it landed on its
stem (which would be much stronger) rather than on the fragile spherical
envelope.

Sylvia

Re: Rather dramatic incandescent bulb failure.


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Stem fuses in many bulbs. designed for moments like these :)

Re: Rather dramatic incandescent bulb failure.


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My halogen work light died today, it came on then flashed a few times,
gave out a loud buzzing sound, finally one very bright flash and then
died. It stayed mechanically in one piece though.

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