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Re: Stray AC current testing
I'm not sure what your marina guy was measuring and calling stray current, since a clamp meter placed around a 3-wire grounded AC power cable wouldn't "know" which lines were unbalanced, they're all in there together.
Not making any assumptions, but it would be necessary, not optional, for someone to actually test the circuit AT the dockside power post, with your cable disconnected, in order to first determine that there was no "leakage" (i.e. potential difference) between the neutral and ground lines, no? And it sounds like they didn't do that, so there's no way to be sure of where the problem was.
The odds are your icemaker just has a 2-lead power cord and isn't doing anything with the ground leg. That like most appliances it is just connecting to the hot and neutral sides, in which case it cannot be involved in any leakage problem. And you can ignore it.
Which leaves the flaky charger--and if it is flaky that's reason enough to look into it. You'd have to start by checking the power socket on the hard, and then the wiring on the boat. Which is not always a clear thing, since "ground" is sometimes tied back to neutral on boats (in gensets, etc.) because there's no real ground on the boat. Sometimes they are wired up like houses, sometimes not, and neither is "wrong".
If there is a GFI in the power post, or hopefully you have one installed where the AC comes into your boat, that should be tripping out if there's any significant problem, shouldn't it? If you don't have one, this might be a good time to add one.