the bulb blowing off by itself cannot open a breaker . however ionization of air because it arched and sustained the short will do that breakers are not fast the short must be there for a long time to open it because of heat caused by the current.

 

Rather dangerous proposition-- wrench melts off-- these situations we heard while working in telecom, as jokes around 2500AH 2V lead acid cells.

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Regards,
Sarma.

 

Also, I doubt the wrench itself actually melts, it's more likely that the battery terminals, which are made of lead, will melt.

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I saw wrenches melting across high power battery terminals. -- wrench across battery terminals without an fuse or circuit breaker.

__________________
Regards,
Sarma.

 

I think every garage in the world has probably experienced this - it's very impressive to see though!

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indeed!

 

On a relatively frequent basis I will have a filament failure accompanied by circuit breaker tripping.

__________________
stevez

 

It just happend to me. (light bulb vs circuit breaker) Re: arcs at 120 VAC; yes, the blue great flash seen when the filament opens, or is open and power is applied is an arc. If you could measure the lumens at that exact point you could determin the current and calculate the resistance. I still can understand after looking at trip current curves of 15 amp breakers how it can trip.

 

There might be hostile atmosphere with heavy lightening etc during this time, over there ?

__________________
Regards,
Sarma.

 

When the wrench glows red-hot then there is no arc.

It takes a high voltage and a gap to make an arc.

__________________
Uncle $crooge

 

You're slipping AG - check the post date, it's months old and already been answered.

__________________
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Lamps are supposed to have fuse wire inside to prevent the low resistance arc from tripping breakers.
Maybe the I^2 T curve, the trip curve, of the fuse wire was a few amps to the right of the I^2 T curve for your breaker.

Arcs have incrementally negative resistance; at some point in the V I curve an increasing voltage causes a decreasing current, but on the whole the V I curve slopes upward and to the right with increasing V or increasing I.

 

There are some extremely cheap light bulbs sold.
They don't have safety fuses.

__________________
Uncle $crooge

 

No hostile weather at time. This is the 3rd time in ten years that it has happend, same fixture subject to vibrations from adjacent stairs. Re: current, the filament does show signs of physical distortion that would indicate high current considering the properties of tungsten. It doesn't make sence but I'm sure the flash seen is from an arc. And Nigel, unless there was a third page in the original discusion, It has not been answered. (If someone wants to talk lead acid stationary batteries, I'm the guy. Charging, step loads, short circuit currents, heat, testing, longevity, etc.)

 

Halogen bulbs certainly don't have a safety fuse - they're always tripping the breakers.

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