Not sure if this ever went through or not.  Re-sending just in case  not. For your boat that is tripping the pedestal breaker, there has been a lot written, and Jim Healy has a ton of good stuff on his website.  Having said that, I have troubleshot/fixed a lot of boats for friends on our marina dock, and will tell you what I find most often, and in the order of problem frequency with #1 being the most common. 1.  Neutral to ground connection on board. Many older boats, including mine, had a connection somewhere on board between the white neutral and the green safety ground.  This was evidenced on my boat by the simple fact that even with all breakers off, the ELCI would trip.  This was easy to demonstrate, but not so easy to find.  The demonstration of the problem was to use an ohmmeter and look for any continuity between the neutral (white) and the safety ground (green).  If there is continuity, then this is the problem, and was the most common problem.  On many boats, you could simple unplug the shorepower cable from the pedestal and measure between the neutral and the safety ground and see some conductivity when it should have been infinity. On a few boats, this issue was hidden by the installation of a galvanic isolator.  In these cases, the simple way around detecting the problem was to cut off all power sources, and go inside the boat and with the ohmeter look for ANY continuity between the neutral pin at an outlet (the larger of the two slots) and the ground pin.  This allows measuring downstream of the galvanic isolator. 2.  Inverter Installation. The inverter must apply a neutral to ground bond WHEN it is the source of power.  Often this is done wrong, and is the source of the issue.  The inverter circuits need to have a separate buss-bar, and again the way they have been (incorrectly) wired in causes the neutral to "feel" a ground connection.  Rather complicated to discuss, so I won't. 3.  Shorepower switch wiring. I found some boats that the shorepower switch was not wired correctly, and did not isolate the necessary white/green bond that the generator power MUST have from the shorepower.  Again, this was the neutral to safety ground commonality issue. 4.  Reverse Polarity Monitor. I found a couple of boats with an old technology reverse polarity indicator that was the problem.  This old-tech indicator was nothing more than a relay that rang a buzzer, and the relay coil was connected between the neutral and the safety ground.  The idea was that in reverse polarity, the white would be hot relative to safety ground, so the relay would energize and ring the buzzer.  The problem was that the small conductivity of the relay coil connecting neutral to ground was enough to trip the dock ELCI.  This was the easiest solution to fix. Perhaps this might give a local technician some guidance in where to look.  Identifying the problem is typically not so hard, but identifying the cause of the problem (or causes) can be a real hair puller.