[jk700]

Right, it's even more complicated. Such breakers also don't trigger at specified current exactly. They have two breakers inside of them, one for overload protection triggering once it heats up, could be an hour for 2x current if starts cold, and one for short circuit protection triggering in less than a second, but on 3x+, 5x+ currents, etc. So a 15A breaker, a 15A outlet and a cable for 15A all could easily see 30A of current for some periods of time and heat up.

[mohaine]

I actually used to calibrate and QC high end breakers for a well know company who's name is a letter and a shape. To pass QC the breakers would need to heat trip when run at 135% Amps between roughly 20-45 minutes. Both too fast and too slow were a failure.

The actual range was a bit different by Ampage which I never quite understood.