What sort of circuit is this on? Unless it is overloaded with other devices, I doubt that over-current is tripping it. Is the breaker a GFCI (RCD in Europe) or AFCI? Both of those are somewhat notorious for nuisance trips, especially older generations. It's not uncommon for the noise suppression capacitors to leak enough current to ground to trip a GFCI. Try isolating the ground pin on the power cord and see if the problem remains. There's a good chance nothing at all is wrong with your Mac.