Well I've got a strange one. When I plug my 2019 Orion T24RB motorhome in to shore power (110 volt, 20 amp) the shore outlet's GFCI (at home) or breaker (at campgrounds) immediately trips. I've tried over three different 20 amp GFCI circuits and the same thing happens. I've tried three different 30 amp to 20 amp adapters and the same thing happens. I've tried two different 30 amp power cords with adapters and the same thing happens. Same if the rig's main panel breaker is switched off. You're noticing a pattern here.
When I plug directly into any 30 amp shore power outlet, everything powers up. When I fire up the gen set, everything powers up. When I turn on the 2000 watt inverter you guessed it, everything powers up. Another pattern.
I've traced and disconnected all the electrical lines from their source into and out of the automatic transfer switch. Into/disconnected = no 20 amp GFCI tripping. Out/disconnected = shore 20 amp GFCI trips. Recall there is no GFCI/breaker tripping with 30 amp shore power, only 20 amp.
What the devil is going on here? Everything has been working perfectly for over a year until this started about three weeks ago, and nothing has changed. BTW the inverter wiring circuit has its own DPDT relay switch. I even replaced that (with a spare I conveniently had) but it made no difference.
I'm stumped and would appreciate your wise counsel before I hand my wallet over to my local RV service dept. Thanks, Gary