Main circuit breaker- I completed a 2 hour routine run of the generator under load, then connected to shore power. (manually ) and turned the main CB back on. I was checking the surge protector time out, as the Surge Guard energized, there was the sound of bacon frying coming from the main power panel.
First reaction was to jump back, --then to turn off the Main CB and disconnect the power cable..
Everything looked normal with the panel cover off. Re-applied power and the main CB again sizzled internally for 4 or 5 seconds.
Removed the CB and it was very hot. Replaced with a new 50amp CB, (Home Depot +-$15) all back to normal.
Don't know where this would have led if I had not stayed there while the power energized. Hopefully the CB on the pedestal or the one in the house would have provided some protection.