Shore power issue

Every time I go to a marina that has redone there shore power using the new 30 amp outlets with GFI breaker , they keep popping when I plug in my boat , I’m fine using a non GFI shore power. Any ideas

Check your inverter. I had the same issues and found out my inverter was wired wrong.

I don’t have one, wish it was that simple

Thank you

You might find a neutral connected to the ground onboard (on the AC side). Start taking it apart where it enters the boat and work you way along the AC wiring, looking for continuity between neutral and ground (white and green). That connection between these two needs to be carried separately from load circuit all the way to the shore power pedestal, otherwise it will trip a GFCI due to ground fault. It will not trip a non-GFCI breaker.



Inverters often have a relay that makes this connection for you when they are used; opening the connection when shore power is selected so line protection works properly.

Here is a link to a decent article about the problem.
Your best bet is to solve the issue on the boat as more and more marinas will be moving in this direction.
As the article states inverters and neutral to ground connections aboard are common sources of the problem.

http://magazine.boatus.com/publication/?m=53247&l=1#{%22issue_id%22:%22587116%22,%22view%22:%22articleBrowser%22,%22article_id%22:%223378579%22}

RW
Short of adding an isolation transformer, there is not an easy amateur (most of us) answer as to dealing with the newer GFIC dock power setups. On our vessel we lucked out and found the correct marine electrician who really knows the ins and outs of vessel grounding as it pertains to the new dock codes.

We re-did each and every 110/240V grounding wire by taking them off the common copper strip, or wherever, and tying all to a central grounding buss bar. Then at one and only one point a ship's ground was established from this common buss. Voila, problems with "new" GFIC trips solved with no IT needed.

So in a nutshell, your entire ship's grounding system needs a careful and experienced eye applied.

This is pretty common. Lots of information out there on boats and GFCIs. Not only the inverter, but something as simple as the little "polarity" light on the power console can cause this.

You can search and find all kinds of troubleshooting suggestions. Here's one I hadn't seen:

My boat will trip a GFCI outlet if I plug it in with the breakers on. I even went so far as to use one of those two-prong to three-prong outlet adapters, plugged into a 15A outlet, to make sure there was no current on the ground prong. One marina I was at had some high-tech system which was able to test each outlet, and it showed my boat was fine; no neutral-to-ground problems.

I've narrowed it down to leaving charger "wall warts" plugged in. I can only guess that maybe these inductive loads cause a surge, and maybe the long run along the power cord and back to the outlet somehow exaggerates it to the point that the GFCI "sees" a voltage difference between ground and neutral.

If I unplug everything, and turn the breakers on one at a time, then plug the chargers back in one at a time, I never get a GFCI trip.

Thank you, I will do that tomorrow. I’m assuming I remove the shore power plug and trace the wires to where they terminate at the breaker panel inside the boat

I have a galvanic isolator , could that be the issues

Do you have 1 or 2 30 amp inlets?

Check your power cords and inlets for neutral to ground faults.

One 30 amp outlet

It’s highly unlikely to be the galvanic isolator. You should contact a yard or marine electrician and have an ELCI master breaker installed. This breaker preforms the same function as the docks GFI. Once the ELCI breaker is installed you will know that your boat is not the issue.

In your case it might be as simple as a ground neutral bond but I have also see appliances that have internal failures cause this issue.

Does your galvanic isolator have a test panel with green and red lights that shows ground and neutral problems? Our Mainship has one and that is our problem when plugging into GFCI shore power. Everything is fine for several seconds as the panel goes through it's tests, then the GFCI trips. The suggestion from the isolator manufacturer was to buy a new one without the test panel. They said they knew about problems with that particular isolator, which was made long before the GFCI outlets came into use. I hesitate to get rid of it because it has found shore power problems three times that could have damaged our boat. Note that even if you have this type of isolator your boat could have other problems.

Turn everything in the boat OFF. Hook up shore power, then start switching systems on one at a time. If a breaker pops, then that system could be your issue.

Same issue here. Plugged into the (new) dock pedestals at H dock, Friday Harbor, turn on the main breaker in the boat and snap...dock GFCI flipped instantly.


There is a new NEC code standard (Article 555.3 issued in 2011) that came into effect in2014 that requires the use of GFCI breakers at all marinas. Basically, the electricity is disconnected with 30 milliamps of ground fault leakage. This is the new standard. If a marina updated or rebuilt for whatever reason, they are now mandated to comply.

I was told it has to do with the negative ground on our boat but that's all I've gleaned. From another boater I know:

What I found was the onboard breaker panel had the ground bus and the neutral bus connected. Separating them solved the problem.

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https://www.powerandmotoryacht.com/maintenance/why-some-boaters-suddenly-cant-connect-to-shore-power

If you only have one 30 amp inlet then I would unhook it from shorepower and turn everything off. Then ohm between neutral and ground. It should be open or no connection. If it is open then turn on circuits one at a time and see if there is a connection on any of the circuits. If there is any connection then some current can flow back on the ground wire. No current should be on the ground. If there is any then the GFCI will trip because it is looking for the exact amount of current returning on the neutral that is going out on the hot wire. If the imbalance is more than 30 mAmps for docks with individual GFCIs or 100 mAmps for docks that have one GFCI for the whole dock then the GFCI will trip. There should be no connection between the neutral and ground except at the source of power, in this case the shore power. If you have a genset then the connection between neutral and ground will be inside the genset. If you find a circuit that has a connection between neutral and ground then you know where to start looking for the problem.

Neutral and ground bonded onboard will cause the issue.

What I am not certain about is if reversed neutral and hot anywhere will cause a GFCI to trip. i.e a plug receptacle hot/neutral reverse will still work an appliance but may send a feed to ground too.

Comodave said:

If you only have one 30 amp inlet then I would unhook it from shorepower and turn everything off. Then ohm between neutral and ground. It should be open or no connection. If it is open then turn on circuits one at a time and see if there is a connection on any of the circuits.

Click to expand...

I hadn't heard of this test. It seems like it would be the most thorough way to be sure. Thank you for posting it!

Even though I don't have this problem, I'm going to try it next chance I get. It's possible there is a connection between ground and neutral somewhere, but not enough current flows back through the ground to trip the breaker.

If the current flows back through the ground wire, it won’t trip a regular breaker unless you overload it. However, it will cause ESD, electro shock drowning, which is the main reason for GFCI on the docks. You could have half of your current flowing back on the ground wire and a regular breaker wouldn’t care but a GFCI will trip. A common reason for this is boats with 2 shore power inlets may have the neutrals tied together so current from SP1 could flow back on SP2 neutral which will trip the GFCI. The OP only has 1 30 amp inlet so that isn’t the issue here. The next most likely thing would be a ground to neutral connection somewhere on the boat. It could be a connection on the neutral bus bar or the ground bus bar or it could be a connection on an appliance. Some household appliances have internal connection from neutral to ground. That is why you start with everything off and check for a neutral to ground connection. If that is ok, then proceed one circuit at a time to find the neutral to ground connection. I use a portable extension cord with a GFCI breaker to simulate the dock. I plug the boat into the extension cord and see when it trips. Most of the docks still don’t have the GFCI breakers to test the boat after you find what you think is the problem. I was working on a friends boat for this issue. He has 2 30 amp inlets. We found 4 problems that would trip the GFCI. His neutrals were all on one bus bar. His 2 voltmeters were daisy chained with the neutrals from one shore power. One of his outlets had been replaced by a PO and they swapped the neutral and ground on the outlet. And his water heater had a ground to neutral short. So just because you find one problem it may not fix the issue at a GFCI equipped dock.

I was lucky and found a bond between the neutral and safety bus bars two years ago. I was specifically looking for it because of what I read here about the "new" ELCI-equipped pedastals. I had not yet had a problem up till then but it was obvious from those early discussions that many boats might. Mine would have. In my opinion, any boat that is tripping an ELCI pedastal needs to look first for a bond between the neutral and safery bus bars before looking for other causes.

What I have seen with boats from the 80s with 2 shore power inlets is that they put all the neutrals on one bus bar. It worked then but it won’t work now with the newly wired docks.

Comodave said:

What I have seen with boats from the 80s with 2 shore power inlets is that they put all the neutrals on one bus bar. It worked then but it won’t work now with the newly wired docks.

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Interesting... I should check for that on mine. I've never hooked up to 2x 30A with GFCI, only a 50A 125/250 split to my 2x 50A 125V inlets. So the neutrals get combined before the GFCI anyway in that case, hence the lack of trips.

Yes, a Y connector will hide the combined neutrals.

Again, it bears repeating once more, incorrect Ground to Neutral connection onboard causes fault current that trips GFCI/ELCI. As well, it is an adverse influence on corrosion and should be checked for that reason alone. G-N connection is only at a prime source of power (Generator, Transformer or Inverter) and only connected into the ship's buss when that source is providing power. (exceptions, but I don't want to digress, seldom on pleasure boats)

Keep in mind that actual ground faults cause fault currents too, that's why the GFCIs are being required. The current observed from the G-N fault is a portion of the boat's Neutral buss load, which then has a parallel path with the Neutral conductor back to the source, a G-N connection at the distribution panel or transformer serving the receptacle. Note, the fault current varies in proportion to the Neutral current, so it varies with the ship's load and load balance between legs in a 120/240V system. This is important to know if you're switching off circuits looking for one that is the cause. If you're seeing an actual live wire insulation fault it will go away all at once when de energized. If it changes with multiple circuits on the boat, its a GN fault.

A galvanic isolator will not influence the GFCI. Monitored models do apply DC voltage to the ground, but the GFCI is sensitive to AC only, besides the current would be very low. A galvanic isolator is redundant if an isolation transformer is installed and wired correctly.

Inverter installations must not have the Output Neutral connected to the Ship's Neutral buss. Transformer installations must not have incoming Ground connected to ship's Ground. Installations of 240V domestic appliances that use a Neutral wire must include 4-wire cords and receptacle wiring - many are sold with 3 wire cords and have a G-N jumper in the connection box. Things that can cause this issue may have been in place for a long time without any observed problems. As often as I've found any of the above, I have also found a jumper between the ship's Ground and Neutral busses. I've found the above problems the cause of fault currents far more often than live wire faults.

The last one of these I dealt with was 3 days ago. There was no observed problem, it was a survey item, fault current measured on the shore Ground. Below, the Ground connections of a transformer installed on a very high end yacht by a supposedly reputable outfit. You see all three grounds on the case stud, and 330 Ma on the meter. The incoming ground wire from the dock gets connected to the transformer shield, the two small ones, and that connection isolated from the case and ship's Ground. Note that the Neutral and Ground are not connected. This is one of those exceptions noted. The boat is equipped with Ground Fault monitoring and one N-G connection for all sources is at the switchboard through a sensing device. This is common on inspected vessels.

EngNate
Inverter installations must not have the Output Neutral connected to the Ship's Neutral buss.
Can you expand on how a circuit is completed for items that have neutral connected to shore buss bar.

SooValley,

Practice in years past, for right or wrong, was to have a single neutral bus. Both inverted and non inverted loads were connected to it.

When not inverting, everything worked as normal. In effect, the inverter wasn't part of the circuit. When inverting, the inverter acted as a source and tied neutral to ground.

The challenge now is that inverters start up with relay closed until shore power ioens it. During that time, neutral and ground are tied.

So, to directly answer your question, the hot wire supplies power to the load which completes the circuit via the neutral wire to the relay and then, via the relay, through both the neutral and grounding conductor wires to the source on shore at which point both the grounding and neutral conductors are tied together.

When the neutral and ground are ties together, current returns via both. The current returning via the grounding conductor pops the GLCI and/or ELCI.

Comodave said:

We found 4 problems that would trip the GFCI. His neutrals were all on one bus bar. His 2 voltmeters were daisy chained with the neutrals from one shore power. One of his outlets had been replaced by a PO and they swapped the neutral and ground on the outlet. And his water heater had a ground to neutral short....

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Glad you survived that visit! In the equipment I design, we have a 2000 Volt isolation spec to meet from L and N to G. I would submit the water world needs the same. Even so, the 2kV will only catch gross clearance failures and inadvertent shorts.

I explained what would happen if someone was in the water with the ground and neutral swapped on the outlet, ESD. He said that he had been in the water between the boat and shore and his muscles locked up. He thought it was due to the water being a bit cold. Fortunately he was only standing on the bottom and was able to get to shore. If he had been in deeper water he may not have made it.

EngNate said:

...

The last one of these I dealt with was 3 days ago. There was no observed problem, it was a survey item, fault current measured on the shore Ground. Below, the Ground connections of a transformer installed on a very high end yacht by a supposedly reputable outfit. You see all three grounds on the case stud, and 330 Ma on the meter. The incoming ground wire from the dock gets connected to the transformer shield, the two small ones, and that connection isolated from the case and ship's Ground. Note that the Neutral and Ground are not connected. This is one of those exceptions noted. The boat is equipped with Ground Fault monitoring and one N-G connection for all sources is at the switchboard through a sensing device. This is common on inspected vessels.

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Run this by us again. There is a IT, and the wiring was OK? N and G are separated, as is the dock earth from ships earth. What was causing a 0.3A shore earth current?? That would have had to be leakage from shore power inlet wiring to the IT?

Basically, the only item(s) on board connected the shore earth are the metal inlet socket, correct?

ps; for clarity, this design used GFCI to trip in case there is a primary to earth IT fault. On the secondary winding side, N bonded to E/G, right?