Originally Posted by psneeld
can't you just add a mini-220 sub-panel?...and even then....doesn't it wind up being the same thing?
That is sorta where I am right now, but even simpler.
I've cut the 120v wires just before they go into the water heater and inserting a male and female plug, make on the heater side.
That way the water heater is totally isolated but still protected through the ground fault of the 220v shore power system.
The cord coming from the transformer ends in a female plug also. That way WH can only be connected to one power source at a time.
I'm using the German plugs, since I have them and I'll remember it's 220!