Thanks for your thoughts.
I'll look at the plug again, but I'm sure it's wired correctly. I'll also check the pedestal...I think I should find 120VAC between the red and white posts, and between the black and white posts, and 240VAC between the red and black posts. Should I find voltage between the red or black and ground?
The voltage is still there with the water heater disconnected, so I doubt it has anything to do with that. It could be that it's significant that the breakers for the water heater and the forward A/C on the 220 panel are adjacent to each other???
6 months ago I added a galvanic isolator between the switch that chooses generator 220 over shore power 220. That only affects the ground wire, so I don't think that is going to be the problem.
I have a 110VAC->220VAC transformer that isn't in play when connec
ted to 200V 50A shore power.
I think that you have two issues. Heating element and wrong wiring.I agree with Eric that there is leakage between the green yellow A/C wire and one of the hot wires. And it also sounds like exactly what has happened to several others when the power cord head is wired wrong in the US. Carefully look at this:
A few things that have not been discussed so far in this thread:
ol>When the heating element needs replacing, it will not continually throw a ground fault. In the beginning of a failure, tiny holes develop in the heating element that allow water inside only when it becomes very hot and the water around it is very hot. You probably need a heating element replacement if it has been 3 or more years since you replaced it.Do you have any devices ON (connected) while all of the breakers are off such as an isolation transformer? If so, look at it for incorrect wiring.I am thinking that the wiring from shore power plug through to the 220VAC panel is faulty, or maybe the pedestal is wired wrong.