Updating the Electrical Panel to fix a ground fault

[Qsilverrdc]

To recap a previous thread (http://clubsearay.com/showthread.php/80417-How-can-I-find-the-ground-fault-in-my-boat), several weeks ago I went to Put-In-Bay (Ohio), and plugged in to shore power. When I turned on my panel main breaker the lights briefly flickered and then no power. The dock master told me that my boat had tripped the ground fault at the street. I have never had any issues anywhere so I began to investigate. (Thanks to all for suggestions) I was quite surprised to find at my home marina, my boat was putting about .85 amps or about 100 watts into the water.

The short answer is that my boat was factory wired so a ground fault condition would exist.
The conflicting electrical requirements are:

• When on shore power bonding (neutral to safety ground) happens somewhere on shore, and not on the boat.
• When on the boat, any AC power source like an inverter or generator must have the AC neutral bonded to the safety ground at the source.

Current ABYC regulations require the source neutrals to be switched with the associated source power. In 1988 apparently there was no requirement to switch neutrals with the Shore/Generator breakers. My boat was designed for 50 amp 120/240 volt shore power service at 30 amps max each line, so 60 amps max power when on shore power. My generator is 6.5 KW 120V single phase, so the 50 amp breakers kind of make sense, except the generator should probably have been 240V, and the breakers 30A.
Here is a partial wiring diagram of how the boat was factory wired.

The Ground Fault happens because some current can flow across the neutral to ground bond at the generator.

 

[Qsilverrdc]

So the simple thing is to replace the breakers with 3 pole and switch the neutrals. Since 50 Amp 240 volt is 180 degrees out of phase on Line 1 to Line 2, the neutral never sees more than 50 amps. in this version each bank (L1/L2) is linted to 30 amps, as in the original design. There is one slight difference. In the original design if the boat was hooked to 2 -30A shore cords that are are on the same phase, the boat would be able to get the 60 amps. Now because the neutral is now switched, the limit would be 30 amps.

 

[Qsilverrdc]

The Repair.

I purchased 2 "C"-series 3 pole breakers, one at 30 Amps and one 50 Amps for about $195 total delivered.
I also purchased a sliding lockout for "C" series breakers for about $35.
After measuring the breakers I determined I would need a adapter plate. I used a 3D printer to make one.
Here is the result:

 

[Qsilverrdc]

The panel before:

And after:

 

[Qsilverrdc]

The panel back before:

And rewired with 3 pole:

 

[Qsilverrdc]

I hope that if you find yourself in a similar situation that this may be of help.

Happy to answer questions.

Richard

 

[MickT]

.85 amps into the water..... more than enough to destroy your sacraficial anodes (or those on nearby boats)

more than enough to kill a person in the water if they get too close....


glad you got it sorted.

 

[vanman59]

Brilliant find and fix. Safety is paramount. I just heard about people getting shocked in the water swimming around boats in marinas, but would never have thought about an OEM wiring issue. My mind was drawn to faulty galvanic isolators.

 

[Qsilverrdc]

Brilliant find and fix. Safety is paramount. I just heard about people getting shocked in the water swimming around boats in marinas, but would never have thought about an OEM wiring issue. My mind was drawn to faulty galvanic isolators.

Thanks..

You know to be fair, if my home marina ground system was up to par, no current would have gone into the water.
It takes a ground faulting boat with bad or weak grounding in the marina.
In my case about 5% of the current found a way into the water. Scary.

Boat is in storage for now. I will have to check my galvanic isolator and grounding in general next season.

Richard

 

[Ike]

Nice fix. Yes, Electric Shock Drowning is caused by current leaking into the water, and can be caused by an improperly wired boat, or an improperly wired shore power outlet on the dock. Marinas need to upgrade to the latest NFPA electrical standards for marinas, as well as owners making sure their boats meet current ABYC electrical standards.

Good that you caught it before it caused a real disaster.