In a nutshell... here are the results of my, uh..."tests"...
Single Pole 20A Breakers FPE on a 40A load to ground tripped between 38 and 74 seconds.
Double pole 20A Breakers FPE on a 40A load to ground tripped between 45 seconds and well over one minute (90+ sec). One breaker failed to trip after two minutes at 200% load. The 30 Amp SQ D Breaker upstream tripped instead, within 2 minutes at 150% load.
A SQ D 20A Breaker 2 Pole tripped within 20 seconds at 40A.
The 20 Amp breakers were the only ones I could test "safely". I had no idea it would take 200% to trip them in less than a couple of minutes. You should have seen me trying to find every high current device in the house to get these things to trip. Toasters, Coffee Pots, Blow Dryers, Heat Guns, Shop Vacs, etc. etc. Scared the cats...
I had it on two GFCI 20A receptacles. But even the #12 feeding them didn't get terribly warm, at double their "rated" current.
By the way, my wife is a nurse and is here when I do these crazy things... Wait 'til I get my Tesla Coil up and running!
