Stray Current


F

Fossil Fuel

Member
This one a mystery. I have 28v AC from my outdrives to ground. I have a dedicated ground rod drivin into earth next to the boat. I was working on the transom kneeling behind the boat and got tickled. I was charging batts at the time. With the charger off I have 10.3V AC. With all the breakers off I have 8.2V AC. With the mains off at the shorepower connection I have 10.8V AC. I have checked for DC volts and its about .06.
The boat has worked fine at the dock with the 30A cord. Whenever I hooked it up to a 15A GFI to charge the batts is trips the GFI.


Sooooooo now what??
 
Yikes, that’s scary. Really glad you noticed before it was put in the water and tied to a dock near swimmers.

Do you have a bad ground at the plug?
 
Start with the bonding connections, something is not connected ( the reason the GFI trips)
There is a break or bad connection between the ground rod on shore and the bock/boat

Can also be an issue with a nearby dock if one is there
 
One of your L1 AC lines are leaking voltage to ground. It is not a direct short because it would kick the circuit protection. So it can be wire insulation that is thin, water around a Hot connection, Electronics: i.e. Battery charger, Microwave .... going bad. The key point here is the GFI is kicking out. That means that there is more then 5mA difference between L1 and Neutral, meaning voltage is going from L1 to ground. This can be very hard to find, basically need to start separating circuits and devices. The suggestion of an electrician is not a bad idea if you are not familiar with AC voltages and wiring.
 
Cebulap said:
One of your L1 AC lines are leaking voltage to ground. It is not a direct short because it would kick the circuit protection. So it can be wire insulation that is thin, water around a Hot connection, Electronics: i.e. Battery charger, Microwave .... going bad. The key point here is the GFI is kicking out. That means that there is more then 5mA difference between L1 and Neutral, meaning voltage is going from L1 to ground. This can be very hard to find, basically need to start separating circuits and devices. The suggestion of an electrician is not a bad idea if you are not familiar with AC voltages and wiring.
Click to expand...

Thats exactly what we are doing. I have a marine electrician working on it.On a 400SS there is 2 30A shore power. The main panel has 2 main breakers. Should neutral be jumpered between both sides? There are separate buss bars for both. There is a crossover breaker when only using 1 shore power cord
 
I would not jumper the neutrals. If you do you will end up with a common neutral and can cause issue, like if you are turn off one breaker to work on wiring the neutral will have power on if from the other breaker.
 
Fossil Fuel said:
This one a mystery. I have 28v AC from my outdrives to ground. I have a dedicated ground rod drivin into earth next to the boat. I was working on the transom kneeling behind the boat and got tickled. I was charging batts at the time. With the charger off I have 10.3V AC. With all the breakers off I have 8.2V AC. With the mains off at the shorepower connection I have 10.8V AC. I have checked for DC volts and its about .06.
The boat has worked fine at the dock with the 30A cord. Whenever I hooked it up to a 15A GFI to charge the batts is trips the GFI.


Sooooooo now what??
Click to expand...
Mine is doing the exact same thing at the 20 amp GFI. I talked to someone at formula and they said the isolator sends out a 5 milliamp pulse every x minutes or so to verify system is working properly.
The only way I could get around it was to turn the power off at the breaker in the boat for the ground isolator monitoring system. I've also found out that you can buy higher milliamp GFCI breakers so this doesn't happen for your AC supply plug. in other words when your isolator sends out the 5 milliamp pulse your GFI will be able to handle a 30 milliamp pulse and will not trip.
I have not tried mine at the boat dock yet but I will be this memorial day and we'll see how it functions.
I can not help you with your stray voltage it may be an issue it may not I have not checked mine.
I would try to measure how many amps the system is leaking. If it's only 250 milliamps or less than that I can't see it being an issue but I am no expert on this.
 
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I recommend attaching the meter and turn on all power and energize all breakers. Turn one breaker off at a time to identify which circuit is causing the issue. Once you find the culprit, you will have to start troubleshooting to see where the leakage is.
With regard to the dedicated ground rod, is it bonded to the ground of the service? If not, it must be bonded together. Is the neutral and ground bonded together at your closest panel? If the closest panel is a subpanel, the neutrals and grounds must always be separated.
If you need phone support, please PM me your number and I can call you.
Just thinking that you may have lost a neutral and current cannot flow back to the main service.
 
IMG_0893.jpg

This is what we found. No wire from the factory linking the 3rd breaker leg to the ground bus. The isolater monitor system was the bug. I am told this has been eliminated from newer boats due to GFI interference. We now have 0 volts to the bonding system and working fine of a gfi....
 
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