I seem to remember there was a discussion here some time back about
someone's shore power tripping breakers. I couldn't find it so if this
is repeated just ignore.

I just ran across an issue at the marina where the regular 20 amp, 120
volt GFCI outlets for power around the yard were tripping when I plugged
the shore power cord in with an adapter. This did not happen at the
marina where the boat is kept in a slip and hooked up the same way. One
of the yard Mech's said he noticed this with all the boats of this type.
The boat is equipped with a ProMariner ProSafe ZincSaver 30.

So I called ProMariner and the tech guy was very familiar with this
issue. He said this model has a form of self test that sends a small
current down the ground line to check continuity with the neutral line.
This is apparently enough to trip a consumer-grade GFCI, but not enough
(according to him) to trip a commercial-grade GFCI. I'm thinking that if
this is true then it may also be enough to trip an old and weathered
commercial GFCI, as my experience with GFCI's in general is that they
frequently get more sensitive over time (at least that's what's happened
with the one's in my house, and I've had no trouble with new one's.

Since the problem does not happen at the marina where the boat is
normally kept (using commercial 20 amp GFCI's), I'm inclined to believe
this is true.

A tip he gave me was to remove the fuses from the ProSafe master
controller if I needed to use the shore power in this situation while on
the hard. Since there's no corrosion issue on the hard and it doesn't
present a safety issue, this may be a good temp solution. Of course, I
suggested the yard change their GFCI's...
Red