Defective Bulb Tripping A Ckt Breaker: How Possible ?

[Robert11]

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

 

[Matthew Beasley]

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

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.

 

[[email protected]]

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.

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

 

[Andrew Gabriel]

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?

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.

 

[Roby]

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

Aliens. They can pass right through the glass, become entangled in the
filament and ... you know.

Roby

 

[Don Kelly]

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

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]

Aliens. They can pass right through the glass, become entangled in the
filament and ... you know.

Roby

 

[[email protected]]

| 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.