GFCI Problems on a Tiny Houseboat

I have installed solar panels on my tiny 38' pontoon houseboat (See Attached wiring diagram) and am having a problem reflecting the grounding for its 120v AC system while at sea and in port.


I have been using all of the 120v AC outlets I installed with no problems, being powered by the Solar panels. However, I have run into a snag. When I plugged in a small 120v AC window air conditioner, its GFCI plug continuously tripped off. I tested all of my outlets which showed correct wiring. Because it is a boat (even though it is currently on a trailer), the grounding connections for both DC, AC, Bonding, and Radio Frequency (RF) components must be grounded to water through the boat's outboard motor by routing grounds through the starting battery's negative post (outboard is grounded to the earth). Researching the problem, SunGoldPower's wiring instructions said to wire the input 120v AC GRID's ground wire to its outside AIO Inverter's housing while the 120v AC LOAD output cable is grounded to a connection inside of the AIO Inverter. Don't know, for sure, that the grounds for the 120v GRID and 120v AC LOAD wires are continuously connected inside the Inverter. Thus, there might be some form of an OPEN ground that the air conditioner's GFCI plug is detecting.

Started researching how to best ground a boat's systems at sea and while plugged into a grounded dock receptacle by watching several grounding related YouTube videos and learned about the shock dangers of swimming around a boat if the boat's grounding design is not exactly correct. Thus, I redesigned the ground wiring as reflected on the attached drawing through an "all" Ground wires connecting Bus Bar to ensure that everything is grounded to the outboard motor's in water surface areas. As reflected in the drawing, I also added a 20 Amp In-Line GFCI for protection against shock while using the 120v appliances inside the boat. I am hoping that rewiring this way will solve the problem of the air conditioner's GFCI plug kicking off. Should I be installing an ELCI instead of a GFCI? If so, why?

I also added an extra 120v ISOLATION (or ByPass) switch. With this "always OFF" switch, I can shut off all of the Solar related (Panels, AIO Inverter, Battery, AC LOAD, and GRID) inputs/outputs at their individual circuit breakers. Then, turn on the added 120v ISOLATION (or ByPass) Switch and use the 120v AC power from the grounded shore plug receptacle, to continuously run my refrigerator and starting battery charger during the periods when the boat is not being used.

If you could just look over the attached diagram to see if I have made any dangerous mistakes in my 120v AC system grounding, I would appreciate it. Thanks in advance. Jim Price

 

<EDIT> This isn't a split phase inverter system, I read the diagram wrong. It's a single phase 120V system. So the first bunch of questions don't make sense.

Does your split phase inverter have an autotransformer or does it contain twin inverters? If it has an autotransformer, what is the maximum current difference between phases? If it has twin inverters, what is the maximum surge current of a single phase? Does your AC have a soft start kit? I suspect your inverter system is not able to supply the starting current without the GFCI tripping. It ought to be able to hold it okay if you get it started. And check to see if any of your AC appliances have a neutral-ground ties as well. With stuff ordered online, it's a total crap shoot. I've seen coffee makers burst into flames when they were plugged in the wall. I've seen 120 V plugs on 240 VAC and 24VDC equipment. The latter caused a nice little fire in a sulfuric acid pump with me laying on my belly trying to back my *** out of a pool equipment enclosure.

 

PhilSweet, Thank you for responding to my questions. As a non electricity knowledgeable person, I really appreciate your help. I don’t know the answers about my SunGoldPower 3,000W AIO Inverter, except that I believe it includes only a single inverter, but I will ask them. I didn’t think that a small 6,000 BTU window AC would require a Soft Start interface. It claims to consume only 550Ws to run and my solar array produces ~2,100W. Reference the Neutral-ground ties, the window AC’s GFCI plug trips immediately, even when nothing else is consuming 120v AC from the inverter.

Since I posted the question, I have been researching how to reduce or eliminate blead over to the earth ground side. I have ordered two 120v ELCB Earth Leakage Circuit Breakers (40A), to replace the standard 2P 40A breakers currently installed (see my attached NEW drawing). I hope these will help solve the imbalance between my 120vv AC Line, common, and ground wiring, thus, enabling the AC’s CGFI to work.

Do you think that adding these ELCBs will help? Thanks again for your help. Jim Price

 

I think the problem is in the Air Conditioner. Many household appliances have the neutral (white) and grounding wire (green) connected inside the appliance. Which is fine for house wiring, but not on a boat where those are not supposed to be connected. If those are connected inside your air conditioner it will trip the GFCI because it will see a ground fault.

 

Learned something today. The AC cord's protection wart isn't exactly a GFCI device. It's (probably) a Leakage Current Detection and Interruption device (LCDI). LCDIs can do more than a GFCI as far as detecting different fault conditions. Meaning we don't exactly know where to begin.

 

You cannot stack GFCIs. This is especially problematic in situations where a device manufacturer provides a GFCI on the cord for any item in a garage. A notable example is a 110v Tesla charging adaptor. The adaptor has its own GFCI. And all modern garage ckts are gfcis. I apologize I do not know the reason it fails, but it does. Ike may be onto something; not sure how a GFCI corded appliance can have the neutral tied to ground; I digress.

There are two solutions. You either remove the GFCI on the cord or in the building. In your case, if you do not have gfci protection already on the outlet or ckt you plugged into; it may be in one of your devices.

I reviewed your diagram and don’t believe it will help. I did notice you are not using class T fusing at the battery and would change that for sure.

 

LCDIs don't monitor the ground wire. They use individually shielded load conductors (hot and neutral wires) and then detect current on the wire shields. The shields are not grounded, they are isolated. The devices are for fire protection, not shock protection. This info wasn't as easy to find as you'd think it would be. There is also a different type of device approved to do basically the same thing (AFCI). All small ACs in the US must have one or the other built in. And ALL of the descriptions and explanations that I read on Reddit and Quora were dead wrong. These cord warts don't protect people. They are there to stop fires. Seasonal appliances have a habit of catching on fire when first returned to service after the off season. The main reason is wire damage, such as a mouse, or your pet parrot, chewing the wires. I got a nasty shock from my clock radio's cord a few years ago, and my parrot never went near it again.

You need to figure out why the wire shields have current on them, or just take in back and get a new one. I guess I'd plug it in to a house outlet and see what happens first.

UL on the various interrupter types - https://code-authorities.ul.com/wp-content/uploads/2014/04/ul_GroundFaultProtectiveDevices.pdf

The code-approved alternative to LCDIs for small ACs - Arc-Fault Circuit-Interrupter Protection | UpCodes https://up.codes/s/arc-fault-circuit-interrupter-protection

LCDI cordset description - L22615-2400W-LCDI-ELEGRP | Make Our Life Safer https://www.elegrp.com/products/portable-protection-device/lcdi/lcdi-lcdi/1054

 

Sorry, I forgot to attach the new wiring diagram. Jim Price

 

Guys, Thanks for all of your advice and support. IKE, do you thinks that it is possible for the Air Conditioner to have their neutral and grounding wires connected internally, as, wouldn’t the GFCI also trip when plugged into regular 120v AC house current? All of my 120v outlets show “Correctly Wired”. Is it possible that the GFCI plug on the Air Conditioner is just defective, thus, maybe replacing it with a standard 3-prong 120v AC plug might solve the problem?

Fallguy, I haven’t yet installed the 120v ELCB Earth Leakage Circuit Breakers (40A) (in place of it’s current two, non GFCI, 120v AC Smart CB 2P 40A) reflected on my wiring drawing, thus, there is currently no GFCI or ELCB coverage on the boat. Once I do install both of the ELCBs, per my drawing, will that constitute a “stack” of GFCIs? If so, should I not replace the AC LOAD CB with the planned second ELCB CB? The only other appliance currently installed is a new 8 Way microwave/convection/air frying/ etc.

Also, do I need to add the recommended class T fusing when both connections between the “House” battery run through a 2P-160A 20Ka DC 500v DC Circuit Breaker?

Having very low electrical knowledge, I really do appreciate you guys taking the time to help me. Let me know if I need to provide any additional info, or make some further tests to isolate the problem.

Jim Price

 

According to the inverter documentation I looked at, The AC input terminal is 120 V three wire - hot, neutral, ground; and the AC output terminal is 2 wire - hot and neutral. The ship's ground is connected to the chassis, not the AC terminal. The shore ground is connected to the AC in terminal, not the chassis.


see page 13 - https://cdn.shopify.com/s/files/1/0323/4090/2025/files/3000W_SPH302480A_20231128.pdf

 

Also, get rid of that bypass switch. It is not safe to do it that way. What you can do is install an empty terminal board near the inverter. You have to air gap both the inverter ac input and output. To bypass the inverter, remove the AC in (3) and AC out (2) connection from the inverter and install on the terminal board to make the jumper. You'll need a ground wire branch connection as well for the ship's ground - see above.

 

Whow, You are correct per the Inverter's manual!!!. Either I wired the inverter incorrectly, or I drew my wiring diagram incorrectly. Must go to the boat tomorrow to see if I wired the inverter correctly. Hopefully, I drew it wrong!

 

philSweet, I am “pretty” sure that I originally wired the inverter per the manual and just screwed up my wiring diagram drawing, otherwise, none of the LOAD 120v AC outlets would be working and test correct wiring.


ABYC and I think I need an ELCI on the shore power (GRID) connection to prevent in-water shock and allow maintenance cutoff of shore power. Fallguy says you cannot stack GFCIs, so should I, replace the current standard 120v AC circuit breaker on the 120v AC LOAD circuit with a second ELCI as reflected on my proposed wiring diagram, or leave it alone. With only one ELCI on the shore power circuit, will the 120v AC LOAD circuit be protected, like with a GFCI, by it?


On trying to create a 120v AC power “Bypass”, should the empty terminal board be “Before” the (GRID&LOAD Circuit Breakers) or “After”? My diagram reflects, inline safety circuit Breakers (or proposed ELCI Earth Leakage Circuit Breakers) which safely interrupt / isolate (for maintenance), for surges, in AC shore power input and output LOAD AC going to and from the inverter?


Once the AC Input (3 shore power wires) and Output (2 AC LOAD wires) are jumpered at the terminal board, how should I wire a system so I can completely turn off (i.e., Isolate) the entire solar array, inverter, house battery and yet continue to power only the internal LOAD AC circuit directly from the shore power cord AC input? This will allow me to charge (using a 120v AC plug in 12v DC charger/maintainer) the boat’s starting battery and keep the 120v AC refrigerator operating during periods the boat is not in use?


When you say “empty terminal board”, do you mean one like in this photo? If not, what type of device/board would you use? Are there “Switchable” terminal board devices that might enable my desired “isolation” of the solar/inverter/house battery and yet allow me to have a hot circuit between shore power and my internal houseboat 120v AC LOAD wiring system segment?


I know I am asking a lot! I also know that you put forth effort to research the wiring on my SunGoldPower inverter. I thank you for your time and knowledge. Any additional help you can pass to me will be greatly appreciated!

Jim Price

 

I agree with Phil.. I have a portable Air Conditioner (not the kind that hangs out the window) in my apartment. It has an LCDI. I accidently tripped the circuit breaker in the main CB panel when I turned on the vacuum cleaner on the same circuit as the AC. The LCDI did not trip. It is possible the LCDI or the Air Conditioner you have is defective.

 

The diagram shows several floating grounds. That may cause a trip on a GFI.