Well, that's what meggars are for. Wouldn't leave after that kind of stress testing without meg testing the circuit.

Load testing with a heating element and a rheostat will often require going over the CB rating, which also has the potential of damaging wire too. DaveT also made some excellent points about magnetic versus thermal tripping. The heating element test might cause the breker to trip thermally but not magnetically, which still leaves potential danger.

Seriously, can you imagine a lawyer having you on the stand, asking you if you actually TESTED to see if the circuit breaker tripped like it should, and then you go on about how electrocution, fire or explosion could result? Guaranteed that lawyer gets a big paycheck, and you joinh the guy on the corner with the tin cup.

Breakers trip all the time. How many times have you troubleshooted a live circuit and accidentally caused a breaker to trip? Did an fire or explosion occur? Of course not! You saw and heard a little spark for a moment, and that was it. What about job sites where part of a building is energized and someone cuts into something? We're not talking testing a 1000A main breaker, we're talking about 15, 20 and 30A branch circuits.

Sure some nasty things have happened with small branch circuits, but those are exceedingly rare.

Over the weekend, I was working in the garage, when an extension cord similar to the one below made that short circuit "pop" after being pulled too tightly around an obstruction:

[Linked Image from ace.imageg.net]

The circuit breaker tripped uneventfully, and since my cord was pretty well beat, it went in the trash. Branch circuit wiring wasn't even a consideration, despite the fact the extension cord clearly shorted.

How many times do you go on a troubleshooting call, reset a tripped breaker, and then it snaps right back? No explosion, fire, extensive wire damage, right? Ok, if you're gonna bring up FPE you got me, call the fire dept, otherwise it's essentially a non-event.

I'm not saying this should be a standard troubleshooting "technique" and totally discounting the potential dangers involved, but if you're on a call for a CB that didn't trip, you'd BETTER make absolutely sure it trips next time a fault occurs others.

Joe


[This message has been edited by JJM (edited 10-31-2006).]