Defective Bulb Tripping A Ckt Breaker: How Possible ?

Hi,
Boy, this is a funny one.
Wife turned on a hall light switch last night, big flash by one of the hall lights, and the ckt breaker tripped.
Was about 2 days since putting in a new bulb there. Was the el-cheapo brand picked up at CVS, and made in China.
Replaced the bulb with a GE one, and so far everything seems O.K.
Question: I can't imagine how anything, like e.g., a broken filament perhaps, can short out the circuit. But, perhaps ?
Can anyone think of a bulb failure mechanism that might trip the breaker ?
Or, do you think the bulb explanation might just be a coincidence ? All works fine, now, though.
Thanks, Bob
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Robert11 wrote:

Something along the lines of:
Filament breaks, arc forms across gap, metal vaporises, plasma forms, envelops more filament, expands to reach connecting wires, very high current flows, gets very bright, very quickly, breaker trips?
--
Sue



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That's exactly right, except it doesn't even need the metal plasma; the low pressure gas fill can form the plasma. You effectively end up with an unballasted discharge tube, which will draw a very high current limited by the resistance of the supply wiring until a fuse or circuit breaker cuts out, or the bulb explodes.
In the UK, filament lamps include fuses in the lead-in wires, but a fast acting circuit breaker can trip too.
--
Andrew Gabriel

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Is the breaker a Arc Fault interupter? They can trip on the arc intrernal to the lamp if the filament shorts out when it goes.
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wrote:

It doesn't have to be that complicated. The standoffs that hold the filiment on cheap bulbs can break and short out the bulb. I had several do it and after the first couple I broke the envelope to see WTF was going on. The stiff wire standoffs were welded together
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Robert11 wrote:

Aliens. They can pass right through the glass, become entangled in the filament and ... you know.
Roby
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Others have given an explanation as to causes --- but GE vs Chinese is not necessarily the answer. How do you know that the GE bulb isn't made in China?. Probably in the same plant that makes Sylvania, Westinghouse, etc. etc where bulbs are run off on a common manufacturers line (as was done in the past in the US) and stamped with the appropriate logo as ordered.
--

Don Kelly snipped-for-privacy@shawcross.ca
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| Wife turned on a hall light switch last night, big flash by one of the hall | lights, and the ckt breaker tripped.
I had this happen once on a 3 bulb mini-chandelier. It had these small socket bulbs of about 40 watts each.
One bulb blew hard (very loud pop) and the circuit went out. After I reset the breaker, none of the bulbs lit up, so I was at first concerned about wiring damage or maybe the switch. I proceeded to change bulbs just to check and that when I started seeing just how bad this was. Fortunately there appeared to be no wiring or switch damage. But the bulb that initially blew also took out the other two bulbs with it. Usually I see a break in the filament in these clear bulbs. But in this case one bulb had no filament remaining. Piese of the glass stem and a couple loose pieces of support wires, along with a very blackened inside surface were all I could see. In addition to that, several spots on the screw-in shell were melted through. The other two bulbs showed significant filament destruction and some screw shell melting.
| Was about 2 days since putting in a new bulb there. | Was the el-cheapo brand picked up at CVS, and made in China. | | Replaced the bulb with a GE one, and so far everything seems O.K. | | Question: I can't imagine how anything, like e.g., a broken filament | perhaps, can short out the circuit. | But, perhaps ?
The arc itself is very high current and can trip the breaker if it stays long enough.
| Can anyone think of a bulb failure mechanism that might trip the breaker ?
Any that leads to an arc. Most do.
| Or, do you think the bulb explanation might just be a coincidence ? | All works fine, now, though.
All is fine mostly because you have a more reliable bulb, now.
Maybe you got a batch of Chinese bulbs intended for Japan. Those would blow sooner, since Japan uses only 100 volts.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
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