Shore GFI tripping troubleshooting

[US1Fountain]

I hauled my boat home this fall for a winter makeover and have the shorepower ran into a barn to a GFI outlet for power for lighting and an electric ceramic heater while in the boat. When I go out to work on/in the boat, I'll plug in the cord in the barn. When I'm done for the day, I just unplug the cord in the barn. What Ive been running into, is if I have anything plugged in and left turned on in the boat, such as several lights or battery charger, as soon as I plug the cord into the barns GFI outlet, it trips. Ive tried another circuit in the barn thats on a sep GFI and it trips also, so I was thinking I have an issue with my boat or power cord. If I have everything off inside the boat, the GFI does not trip. (Breakers can still be on but no devices in the 'on' position) Also, once it trips, I can push the reset button in and it works fine then. Sometimes it may take 3 resets to stay in. Its always just the initial plugging in of the shore power. I've checked everything I can think of, had the AC panel off and checked all the wiring. The water heater has been disconnected, as well as the AC unit the whole time during the makeover, with the wire ends taped up so no connection across any of the wires. Ive tested every circuit using my outlet tester (the tester with 3 leds that show if correct or mis wired) and it shows all is good. If I have just 1 light turned on when I initially plug the boat in, its not a problem. Its when I have approx 3 lights that it trips when the shore power is plugged in. The power panels reverse polarity light is green. Once I'm inside the boat working, I can run 2 heaters, a few lights, and a shop vac, all pulling about 25A according to my panel and never have any barn GFI trips, unless I accidentally touch the wire leds, then the GFI trips as I would expect.
I'm thinking if there was an issue with my boat or my power cord from barn to boats shore plug I'm overlooking, it would trip the GFI constantly, not just at initial plug in stage. Only thing I can think of is the barn has 2 weak GFIs???

Any thoughts or suggestions? Thanks

[senormechanico]

Damp wiring?
Are these LED's the peel and stick type? If so, maybe they are conducting into damp fiberglass to ground.

[CapnSparky]

I had a similar experience during an out of the water insurance survey some years back. The surveyor had me convinced that my wiring was defective for exactly the same issues you are experiencing. I'm a retired electrical engineer and can generally figure these things out. And I also have a boat I bought new and was wired correctly from the factory....turns out my Heart inverter/charger, operating normally, was the source of the tripping GFI. It's unlikely I'll use that surveyor again. Jusy saying your charger may be root cause?

[smac999]

Originally Posted by CapnSparky

I had a similar experience during an out of the water insurance survey some years back. The surveyor had me convinced that my wiring was defective for exactly the same issues you are experiencing. I'm a retired electrical engineer and can generally figure these things out. And I also have a boat I bought new and was wired correctly from the factory....turns out my Heart inverter/charger, operating normally, was the source of the tripping GFI. It's unlikely I'll use that surveyor again. Jusy saying your charger may be root cause?

your inverter is likely wired wrong with a common neutral bus instead of separate shore and inverter neutral buses. see it all the time. will trip a GFI / ELCI at plug in. due to the inverter G-N bond taking a few secs to relase itself when plugging in. a correctly wired boat will not trip a GFI / ELCI.

I don't trust any new boat wiring. what I see new from factorys are often a joke. saw a boat last week leaking 7a AC into the water. 100% factory screw up. some of the new boat battery designs I see are crazy.

[smac999]

as to the OP you might have a ground - neutral bond. if no current is flowing, it won't trip a GFI because nothing is flowing through either wire. if stuff is turned on. then some current will go through each wire, and trip the GFI. with the boat unplugged stick your ohm meter on the ground and neutral bus. it should read infinite.

if you have a pass through inverter. that could also be your cause. see above.

[US1Fountain]

I do not have an inverter

The ‘3 LED’ tester is the type that you plug into an outlet and it will check for correct wiring and illuminate the Leds either red ifa fault is found or green if all good. All of my outlet circuits checked good. Made no difference which circuit I was using to plug in my light. Any number over 2 and it would trip the GFI.

Boat is outside but covered by a tarp, so dampness could be a possibility, but it’s done this since I brought it home in fall.

The ground neutral bond sounds likely. I will check that. I didn’t have any problems at the lake when plugged in at my slip.

Thanks

[Colin A]

Originally Posted by US1Fountain

I do not have an inverter

The ‘3 LED’ tester is the type that you plug into an outlet and it will check for correct wiring and illuminate the Leds either red ifa fault is found or green if all good. All of my outlet circuits checked good. Made no difference which circuit I was using to plug in my light. Any number over 2 and it would trip the GFI.

Boat is outside but covered by a tarp, so dampness could be a possibility, but it’s done this since I brought it home in fall.

The ground neutral bond sounds likely. I will check that. I didn’t have any problems at the lake when plugged in at my slip.

Thanks

GFCI trips at 5ma ELCI trips at 30ma so that may be why it trips at home but not on the water (unless you have a GFCI on the outlet at your slip. )

Dampness can be a possibility have you tried changing the cord? My neighbor left a cord running to his shed for a couple years all the sudden it started tripping out the GFCI. Insulation was leaking to the damp ground after being walked on rained and snowed on for 2 years.

Does the panel have just a reverse polarity light or a reverse polarity trip? Some of the older boats have a trip unit which some GFCI and ELCI units do not like.

If you have a clamp on amp meter you could run it around the cord to check for leaks. That would eliminate the GFCI as the issue.

This link gives the run down
Leakage current measurement basics

[Redline452]

My previous C&C had a reverse-polarity trip as part of its main breaker, sensing voltage between neutral and ground. The problem was that it was sensitive to the sequence of connections made while the plug is inserted. The longer ground pin contacts first, then if the Hot then contacts before the Neutral, any active loads would put voltage on the Neutral side, tripping the boat's breaker.

I could be that your GFI is sensitive to that condition as well. You could also have a very small leakage current below the GFI threshold, but sufficient to cause a trip when neutral is not present . A quick test is carefully inserting the plug at a slight angle left and right, to see if making neutral-before-hot avoids the trip. Or if that shore side outlet is switched, plug in first, then turn it on.

[Cadence]

As a WAG because your plugging in with a surge the GFI is detecting a little dampness. Nothing abnormal. You're probably arcing up the plug and receptacle also.

[deblen]

Are you plugging into a standard 120 vac 15 amp,or possibly 20amp max, N. American outlet at the barn?
If so,you should not be able to draw the 25amps indicated on your boat's ac panel meter.
Is the the trip because of a ground fault (you seem to have eliminated that possibility by tests) or is the GFCI also a regular over-current breaker & it is tripping due to initial surge over-current ?

Electric heaters are available up to 1500watt rating @ 120vac. This equates to approx 13amps/heater & is the max. full load for a std. 15amp 120vac ckt.
What wattage are your two heaters?

Len

[Stu Jackson]

Originally Posted by US1Fountain

>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
I can push the reset button in and it works fine then. Sometimes it may take 3 resets to stay in. Its always just the initial plugging in of the shore power.>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>
Only thing I can think of is the barn has 2 weak GFIs???

Any thoughts or suggestions? Thanks

If it's not the cord, and you find your wiring is OK, these little things do go bad...

Nothing lasts forever.

Or, you could replace them for not much $$ and see if that fixes it.

Good luck.

[capblasters]

I like all of the discussion above. I had a similar issue and was told to check out the defrost cycle on the refrigerator / freezer. Turns out it cycles a couple of times when first turned on. I managed to disconnect the defrost element and this confirmed the issue. I have yet to completely resolve it - my temporary fix is to leave the defrost element isolated when on shore power.

[US1Fountain]

Originally Posted by deblen

Attachment 164684


Are you plugging into a standard 120 vac 15 amp,or possibly 20amp max, N. American outlet at the barn?
If so,you should not be able to draw the 25amps indicated on your boat's ac panel meter.
Is the the trip because of a ground fault (you seem to have eliminated that possibility by tests) or is the GFCI also a regular over-current breaker & it is tripping due to initial surge over-current ?

Electric heaters are available up to 1500watt rating @ 120vac. This equates to approx 13amps/heater & is the max. full load for a std. 15amp 120vac ckt.
What wattage are your two heaters?

Len

Yes, a standard 120V Ac circuit on a 20A breaker. It is GFI 15A do to the the 2 verticle plug slots, not a 20A verticle/horizontal slot for the 1 plug prong. The issue is not an overload condition, but a fault as I understand it. The 25 A was the reading from my panel. I didnt verify the accuracy of it, but the thought of it not tripping the breaker did cross my mind.I even felt the cord to see if i twas warm, but it wasnt. I just kinda blew it off. I do not have the heater specs with me. I will look next time out. But I can only assume with both those and a a couple lights, and now the battery charger being used to power the cabin lighting, I'm pushing the bar some. But even with a full max load once I am plugged in and not tripping any GFIs or breakers, this is what confuses me.
Once plugged in to the barn, I can load it up with no problems. Its just that act of actually plugging the shore cord into the GFI with just a couple of lights that will trip it. Once it trips, I can reset a couple of times to kind of 'jump start' if you would, and then all is good. Im ok if its just a condition while on land. Just dont want there to be a problem once I relaunch. Either a safety or a risk of eating my drives up.

My fridge and every other none oulet circuit is left in the off position on my panel.

I have considered replacing the GFI's as the easiest/cheapest test. Was just thinking the odds of both being bad being questionable.

Reverse polarity is just light.

[Cadence]

I guess your barn was never inspected. A 15 A receptacle on a 20 A breaker. All kidding aside I don't think you really have a problem other than surge. I hate GFIs because they can be a pain in the butt, but standing in water might change my opinion.

[US1Fountain]

Yes it was inspected. 15A outlets have a 20A pass thru rating. As long as there is more than a single outlet, 20A breaker is the norm. If the outlet was a single outlet only, not your typical duplex which qualifies as 2 outlets, then yes it would be a 15A breaker.

As far as my problem, I think you are right. Today when I left, I only left the battery charger breaker turned on. WHen I unplugged the power cord from the outlet in the barn, it tripped. It been raining for several days and really damp. I was focused on the job for today, so didnt get time to do any electrical testing.


Thanks for all the suggestions.