The GFI of the shore power outlet is always tripping

May 21, 2013
45
Hunter 410 Stuart
Hi,
All of a sudden, the GFI on the shore power outlet is tripping when putting on even the lightest load. The boat sit‘s on the dry at the boat yard. To charge and maintain the batteries, a battery charger is always on. That was never a problem, until a few weeks ago. The boat is a 1999 Hunter 410 sailboat
There is a GFI equipped outlet from the yard I‘using. I have a 30Amp power cord plugged in. On the boats end, the cable and the boat are equipped with a smart plug.
I have tried many things to find out the cause, why the GFI tripps all the time:
- Changed the shore cable
- removed the battery charger (thought it might be shot)
- etc.

Sometimes, I get the 115VACdisplayed at the electrical pannel, sometimes it even tripps before I can read the instrument. Sometimes it does not trip, even with e load such as a larger dehumidyfier on (rated at 15 Amps 110 VAC)
I would highly appreciate any thought or hint.
Thanks.
Marco
 

leo310

.
Dec 15, 2006
635
Catalina 310 44 Campbell River BC
Has the yard power got a GFI if so that maybe your problem.
 

SG

.
Feb 11, 2017
1,670
J/Boat J/160 Annapolis
Is the breaker "on shore"? -- I know that you "on the hard". Or do you have on on the main AC feed on-board (i.e., on the boat side of the inlet outlet?

I suppose it it could be the circuit breaker. Can you find another source and see if that happens? You could use an appropriate sized extension cord.
 

dakno

.
Jun 22, 2009
209
Hunter 41DS new orleans
Its the shore power GFI, These outlets are very sensitive and normally have to be replaced every 3-5 years
 
Jun 4, 2004
1,071
Hunter 410 Punta Gorda
Maybe you have a ground fault on your boat. I had a cross tie wire that should have been removed when the previous owner installed the inverter that was causing a ground fault.
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
The most common reason for a tripped GFCI is an improperly wired vessel with a ground/neutral bond on-board. A 5mA trip household GFCI should not be used to plug in a 30A service vessel but on the hard it is what it is. That said, a correctly wired vessel should not trip even a 5mA household GFCI. GFCI's, ELCI's and RCD's expose a lot of incorrect or unsafe AC wiring so take this as a good thing not a bad thing.

Keep in mind the GFCI leakage current can be cumulative so if your yard neighbor is on this same GFCI circuit, and you each have a 2.5mA leak, then pop it goes.You were only half the issue in this case....

Some common causes of GFCI trips:

An inadvertent neutral / ground bond on-board, far too common actually, this can cause the GFI to trip.

A galvanic isolator that has a self test monitoring feature will also trip a GFI. (newer fail safe models do not have this issue)

You wire through an inverter/charger that "auto transfers" & the transfer switch-speed is too slow.

Other boats are on this same circuit and the mA leakage is cumulative so you may be the final straw.

Older 120V appliances that have neutral bonded to the case ground

A water heater with cracked element can also cause a trip

HVAC or other PCB's that mix low voltage and high voltage.

Incorrectly wired SHORE-OFF-GENERATOR switches.

All the GFCI does is look at the balance of current between AC Hot and AC Neutral. In other words the amount of current that enters the boat must leave the boat within 0.005A. If the circuit is working properly, and you're drawing 5A of AC current then you will have 5.000A on hot and 5.000A on neutral. If there's leakage finding it's way onto the ground wire (or into the water if you're in the water) then you would trip at 5.000A hot and 4.995A on neutral. Also GFCI's are quite fast and respond to an imbalance in about 25 milliseconds.

The problem of GFI nuisance trips is almost always on-board your vessel. If you know someone with a GFCI tester, such as the Ideal Sure Test, then you can rule it out pretty quickly. GFCI's do fail but it's much more common for the issue to be improper wiring on your boat.
 
Jan 12, 2011
930
Hunter 410 full time cruiser
Hi,
All of a sudden, the GFI on the shore power outlet is tripping when putting on even the lightest load. The boat sit‘s on the dry at the boat yard. To charge and maintain the batteries, a battery charger is always on. That was never a problem, until a few weeks ago. The boat is a 1999 Hunter 410 sailboat
There is a GFI equipped outlet from the yard I‘using. I have a 30Amp power cord plugged in. On the boats end, the cable and the boat are equipped with a smart plug.
I have tried many things to find out the cause, why the GFI tripps all the time:
- Changed the shore cable
- removed the battery charger (thought it might be shot)
- etc.

Sometimes, I get the 115VACdisplayed at the electrical pannel, sometimes it even tripps before I can read the instrument. Sometimes it does not trip, even with e load such as a larger dehumidyfier on (rated at 15 Amps 110 VAC)
I would highly appreciate any thought or hint.
Thanks.
Marco
Your boat has galvanic isolators on it and you didn't go and do any AC wiring lately so it's not likely it's your boat. GFI outlets do go bad and need to be replaced. Have you just replaced outlet?
 
Oct 2, 2008
3,807
Pearson/ 530 Strafford, NH
We stayed at a marina that had all the outlets on a single 12 gauge wire for those working on their boats. I would run my buffer until someone would use a drill, then the power would go out. It would take a lot of coordination but we would compromise and be able to use the power off and on. Then a person from across the yard would see we had power and they would use a 100 ft. extension and the power would go out for everyone. I then would take an early lunch.
 
Jan 18, 2016
782
Catalina 387 Dana Point
Listen to Maine Sail. He knows of what he speaks. As he points out - think of current going 'out' the hot wire. Then current comes back 'in' the neutral wire. If those aren't equal, a gfi will trip. Why? Because no current should ever go anywhere else - not on a ground wire, or on the lady holding the hair dryer in the shower, or you when you're descending your boarding ladder to clean the bottom. Any power 'out' that's not coming 'in' is going somewhere it can kill somebody so a GFI prevents that by tripping. That's a very good thing.

But GFI outlets do sometimes go bad (particularly the cheap consumer-grade crap from the home center). You need to determine if that's the case. Use the tester Maine points out. You also may try unplugging the boat, and try some load directly on the GFI. If the load doesn't trip the GFI in isolation but it does on the boat... it's way more than likely the wiring on the boat. Neutral to Ground bonds are a common problem. Flaky GFIs also can be more sensitive to inductive (motor) loads than resistive (lights, etc) loads.

A GFI tripping is not an overload - it's a safety check on "power out must equal power in."
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
And, since no one seems to have mentioned it yet, may I ask why your first step was to rewire the pedestal?
 
Jun 1, 2009
1,737
Hunter 49 toronto
This might be it...
A lot of panels have an “incorrect polarity” light.
How that works is that they have a led or neon connected from neutral to ground.
If you have one of these, clip the light lead. See if that fixes it
 
May 24, 2004
7,129
CC 30 South Florida
Do you mean the outlet on the Boat Yard side? Plug something else and see if it trips, those outlets can go bad. Have the yard check out their circuit.
 
Oct 24, 2010
2,405
Hunter 30 Everett, WA
Maine Sail is right. Most likely it's your boat. I'd begin like this: Open all the AC circuit breakers on the boat. Does the GFCI trip? If not, close one breaker at a time until you find the offending circuit. If it trips with all breakers open isolate in the primary power areas such as a galvanic isolator, panel polarity light, volt meter, etc. It isn't magic.

Ken