Well it was my best guess? Based on the info I had, hard to think of another cause. Plus a 15A breaker will allow higher current for a time. It definitely drew big power for a short time to do that.
If a 15A breaker really blew at 15A, then the wires couldn’t have burned like that.
I am at the ACS factory with Paolo at the moment and it’s what Paolo thinks as well.
P.S. the other clue for me, is it didn’t fail last night because the brew boiler was already how any using very little current at the time the steam SSR locked on. Of course when you switched it on in the morning, brew boiler was cold and max power drawn.
Hope it all makes sense now.