ECN Forum Forums General Topics of the Trade General Discussion Area Breakers not tripping

Edit to add smiley....

I'm not going to try to be overly technical - because this is just the way I see it. Others may clarify or obfiscate at will....

Time, in the grand sceme of things AC is very short, and exceadingly long... The amount of time it takes to do a while lot of arching, and blasting of metal away opens and closes the circuit really quickly. That buzzing is about the frequencey of it... Not un-like welding.... The smaller points of contact just get expelled away - like a fuse, and then reconnects.... What you were doing was blowing away the portions of wire faster than the CB could gather the energy to trip, which takes some time.... Upwards of a second or two, but blowing away metal in micro-seconds in flashes of white light.

Common HACR breakers will hold much more than thier rating for some time - each are different - but relitively simular. About 175 for a minute or two, but will hold hundreds - thousands for a shorter time. Since the GE example was illegible, try this one: http://www.eatonelectrical.com/unsecure/cms1/TC00302001E.PDF

Note that this breaker simular to what you are using, can hold at minimum 600 - 1200% (PERCENT) of its current rating for 1 second! ~2400 amps In that amount of time you could have opened and closed the circuit 60 times - every spark of the arching.... Each not enough time to trip the breaker. Collectively, they may heat the elemants of the breaker to the trip point, but over a longer time. Look at the graphs agian and notice that the breaker can hold many thousands of times it's rating for milliseconds. Which is what the breaker saw, a whole bunch of millisecond shorts at several thousand amps a piece. Or, whatever the transormer feeding the neighborhood could supply at that distance from it.

Now if you had bolted, or wirenuted two wires together as a direct short you would be looking at a shorter reaction time, but then again you might be going to the hospital for arch-flash burns from the breaker exploding after it superheated any gas and metal in the breaker to the flash point. Because even though you may have had AIC calcs done, they are still only calculations... If that particular breaker can take it is another story. So don't do that either.

"So you learned that a teacher was dumb enough to get her jewlery into a hot outlet. The thing to have done was replace the outlet and move on. " Mxslick - thats priceless.....