The problem was in my shore cable. I have no clue as to why this failure happened exactly when my generator was started up. Maybe it’s related, maybe not.
I have now fixed my shore cable, and all is good once more.
On the bright side... now I know all about that changeover switch 😉
Eric, I think that is the timer unit in Alexandre’s pictures. This is not present in my 54.
I do not have the big invertor, so my changeover is just between gen and shore. Maybe that’s related to inverter?
Now, to the next task ... replace the main outhaul...
Many thanks all