light bulb explosion

Sorry if it's the wrong newsgroup but I've came here before so I thought of asking here first... Today in our home kitchen a standard 100-watts light bulb "exploded". It happened just like that for no apparent reason, my girlfriend was in the kitchen reading and could have been injured by the flying glass from the bulb. The fuse didn't open. Has anyone ever seen or experienced something like that before? Why would that happen? Thank's for any info and sorry for my approximate english.

Patrick, from Quebec, Canada.

Reply to
PatrickM
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Over the years I have seen several light bulbs explode with a sea of broken glass and sparks. I don't know why they went out in such a manner. One time was in a underground hallway leading to the University of Saskatchewan Library right in the middle of final exams! At the time I assumed it was because of too much angst.

Regards,

Eric

Reply to
Eric Lambi

Light bulbs ordinarily have a low internal pressure (much less than atmospheric pressure) so do not actually explode, even if the filament overheats for some reason (like a partial short circuit). But the glass can shatter from internal stresses (not properly annealed) or from being splashed with water.

My parentheses keys are tired now. :-p

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John Popelish
Reply to
John Popelish

In my less sceptical days I recall reading that exploding light bulbs was a well known symptom of poltergeist activity. Were there also any books seen flying across the room?

As John said, bulbs should implode. But of course gravity then takes over and 'flying glass from the bulb' would be a natural description, especially from someone deeply immersed in a good book!

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Terry Pinnell
Hobbyist, West Sussex, UK
Reply to
Terry Pinnell

Halogen lamps are particularly prone to this and can be quite dangerous. I once saw one explode on the Carson show. It started little fires everywhere the glass shards landed including the guests dress. Usually there was a scrim over those studio lamps for safety. This one must have been missing. I have seen them forming huge bubbles of quartz just prior to exploding.

Richard

Reply to
Richard

Sometimes the glas part of the bulb explosion-like separates from the metal socket and flys off (in one pice, at least until it hits something).

The second possibility is that the bulb imploded, that is the glass bulb itself cracked under the force of the (partial) vacuum inside. The fragments then move towards the centre of the bulb (in an explosion they would move away from the centre). However, as the fragments don't just stop at the centre, an implosion is operationally indistinguishable from an explosion.

Both occasionally happes (often when the light is switched on or after a brown out), without any apparent reason and unpredictably. Just one of the risks of modern life, I guess.

Reply to
Dr Engelbert Buxbaum

I can beat that. I was saw a sherry glass spontaneously fracture into a myriad of shards right before my eyes, for no apparent reason at all! I can understand the odd light bulb going 'pop' from time-to-time since it is, after all, hot, stressed and has a limited life expectancy. One expects a bit better from a simple drinking vessel, though...

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Fat, sugar, salt, beer: the four essentials for a healthy diet.
Reply to
Steve Evans

I stumbled across the explanation under a Britannica entry for Argon.

Manufacturers put argon in light bulbs as an inert fill gas. Unfortunately argon has a low breakdown voltage, so if the filament burns out, an arc will leap across the broken ends. So, manufacturers put some nitrogen in the argon to raise the breakdown voltage.

But sometimes an arc will strike across the broken filament ends. When this occurs, the normal "yellow" light bulb color will turn brilliant blue-white for a moment (until the filament is vaporized by the arc, and the arc quenches out.

But sometimes the arc continues for too long. Or perhaps the manufacturers got the gas mixture wrong. The hot arc will cause the argon pressure in the bulb to skyrocket. The bulb will burst with a bang.

(A similar thing occurs if you put a bulb in a microwave oven for a couple of minutes. The hot plasma inside the bulb will vaporise the filament parts, then cause the bulb to explode via overpressure.)

Reply to
William J. Beaty

Back when I went to college I worked at a number of television studios. Occasionally I would have to replace the halogen lamps in the studio lights. They were typically rated 1000W and "ran" very hot. The bulbs were wrapped with special handling paper. If you accidentally touched the bulb with your bare fingers, the slight amount of oil from your skin would be enough to cause an instant explosion the first time the bulb was turned on (they "docked" your pay if that happened).

I doubt that is what happened to your 100W bulb. Given that millions of bulbs are manufactured each day? week?, statistically some will have slight flaws that will cause this type of failure.

Tom

Reply to
tlbs101

Well that explains a lot! Sometimes when a bulb goes out you can get it to burn again by flicking it. Sometimes the filament will fuse back together and it will burn again.

I have seen that brilliant blue-White arc sometimes when a bulb burns out. It can be quite brilliant and very violent.

We also used to use dichoric glass in front of quartz lamps to change the color temperature.

Richard

Richard

Reply to
Richard

I'd guess so, their operating temperature is much higher than that of ordinary incandescent lamps. The screen btw helps not only against flying bits, but also screens the UV ratiation produced by the lamp (higher temperature -> more light of shorter wavelength)

Reply to
Dr Engelbert Buxbaum

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