New marina wiring

Moved to a new marina with the updated gfci set up.
My boat trips the shore breaker as soon as I turn to shore power even with all my breakers off. Connecting my shore power cord doesn’t do it.
Any suggestions where to start troubleshooting this issue?

what's between the main breaker and the individual circuit breakers?
or
what's still powered on when all the individual circuits are off?

Do you have an inverter? Is the neutral on the output side separate from the neutral for the rest of the boat.

When inverters are uncovered, they bond earth and neutral. Once they detect power, they break that bond. The delay is usually enough to pop shore RCDs.

Other than that, shut off all AC breakers, including main, plug up and turn on shore pedestal. Then turn on AC main. Then turn on the other breakers one at a time until something trips it. Then debug that circuit, then keep going.

If main trips it with all breakers off, make sure there are no fused loads without breakers, removing fuses as needed. If it still pops, really make sure there are no off breaker loads, and then start debugging neutral and ground.

To do that, disconnect from shore power, turn off other power SourceSafe, and check from neutral bus to ground bus with an ohm meter. If it isn't infinite, look for the offending connection. If you don't see it, start plucking off neutrals or grounds until you find a connection or the circuitbthqt is making the connection, then debug from there.

You are not alone. This has been discussed here (and lots of other places) at some length.

An inverter can be one culprit, as mentioned above.

Another common one is the "reverse polarity" light. If you have one, it's probably connected between the AC neutral and load. In other words, a direct "ground fault."

But any place ground and neutral are bonded can be an issue. Before GFCI, this would work just fine, even if it's not considered safe. You may find one bus bar with neutral (white) and ground (green) wires all terminated together. Or you may find one isolated connection somewhere.

I think that, for there to be a difference between the ground and neutral, there must be something somewhere connected to the hot wire that's powered on. So looking for something powered - even as small as the "reverse polarity" light - is a good place to start.

Do you have 1 or 2 30 amp inlets? If you have 2 inlets then it could be that the neutrals from the different inlets are connected together. It was bery common to put all the neutrals on 1 bus bar. Before the GFIs it would work, but not anymore. Our last boat would trip the dock breakers just by plugging in the power cords with the main breakers off. The neutrals were all on 1 bus. Along with some other minor issues. I put household GFIs on our dock and they trip at 6 mAmps. The marine breakers will trip at 30 mAmps if they are for a single slip or 100 mAmps if they do the whole dock.

CaptTom is correct. Your neutral (white) wire is connected to the ground (green) wire somewhere on the boat. It may be difficult to find.

Steve D'Antonio wrote an excellent article about this.
https://stevedmarineconsulting.com/electric-shock-drowning-and-elcis-explained/
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Rossland said:

CaptTom is correct. Your neutral (white) wire is connected to the ground (green) wire somewhere on the boat. It may be difficult to find.

Steve D'Antonio wrote an excellent article about this.
https://stevedmarineconsulting.com/electric-shock-drowning-and-elcis-explained/
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This is not likely the problem. Turning all the circuit breakers off would mean no power and no power would mean no leakage. Something is getting power after the AC main switch and before the circuit board panel. It is not uncommon for power to be split off the AC Main with some going to an inverter and some going to the panel. Making the inverter a possible suspect. Something else could be taking power directly from the AC main (polarity led or even a power on led) which would make it a possible suspect.

if the neutrals between inverter circuits and non inverter circuits are comingled this could cause the problem

@CaptTom #4:

Another common one is the "reverse polarity" light. If you have one, it's probably connected between the AC neutral and load. In other words, a direct "ground fault."

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Actually, the reverse polarity light is connected between N and G and the resistance between N and G must be >25kohms to be ABYC compliant.

The best advice would be to hire a certified marine electrician who is familiar with the new wiring codes.

The white and green are connected at a power Source , the inverter is one , the noisemaker an other.


If in depth trouble shooting is required a battery charger or older 120 fridge , or air cond. would be first place to start .

Comodave said:

The best advice would be to hire a certified marine electrician who is familiar with the new wiring codes.

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If it's anything like all the other trades right now, you'll be lucky if anyone returns your call, and the ones that are not busy are not the ones you want. Let's not even talk about what people are charging right now.