It all depends..... The hype is that FPE doesn't trip... I have yet do see that happen, and I am SURROUNDED by FPE... ( The ones here in Canada seem to work fine albeit S..L..O..W to trip)... I have seen GE trip when they shouldn't and westinghouse not trip.... Breakers are a mechanical device, therefore I think they are more prone to failure due to some mechanical problem, than fuses, which simply melt and break the circuit...
But thats just my opinion...
A.D
