Shore power while on trailer

M

Moosewood

Member
Joined
Feb 21, 2026
Messages
23
Fluid Motion Model
R-23 (Outboard)
Hi Tugnuts!
First season off the water and storing in an open air boathouse on San Juan island. It’s is a 2020 R-23.
I set it up so I can plug in my shore power cable to an outlet. I am in the middle of winterizing and general cleanup and while washing down and draining my cockpit bilge I stuck my little finger in the keel drain plug to clear out some debris and could feel a tingling electrical current.
I discovered that the drain plug is grounded but should I feel current ? If I disconnect the shore power and just run batteries there is no current felt.
Maybe this is by design.
Thanks all and have a great winter!
Mark
2020 R-23.
Mineral Point , San Juan Island
 
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I wouldn't think so but I'm no expert. I have had my 23 on shorepower while on the trailer for a good chunk of the winter and spent a fair amount of time doing "boat chores" and never felt any stray currents. I'm getting ready to winterize mine this weekend (on the trailer and plugger in). I'll pay attention and report if I experience something similar.
 
Thanks Mik.
I wonder if this is because things were wet and the ground underfoot was wet too. But even so I don’t understand why the ground would bleed current.
 
That sounds like a potentially dangerous problem. I would have a marine eletrcian check it out. There should be no stray current in your boat. Are you familiar with using a multimeter? Check all of your eletrical connections. Good luck.
 
R23 Kingfisher said:
That sounds like a potentially dangerous problem. I would have a marine eletrcian check it out. There should be no stray current in your boat. Are you familiar with using a multimeter? Check all of your eletrical connections. Good luck.
Click to expand...
Thanks for the reply. Yes I am familiar with a multimeter. I haven’t used it yet on this issue as I had to leave town for a bit. That’s my next troubleshooting tool I’ll use.
One thing I did notice is that now that everything has dried out I don’t feel that current anymore. Doesn’t mean there isn’t a hidden problem as like you said there shouldn’t be any current but thinking if there was enough water spray in the areas of the battery or the shore power unit that that could have caused it.
Edited : actually I can still feel the current but not as intense.
 
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Are you using a 3 prong grounded outlet and connections or just a two prong (hot and neutral) plug somewhere between your boat and power source?

It's a common problem in boatyards that don't have grounded electrical outlets. The boats (ABYC compliant boats) are wired with the AC grounding conductor connected to the DC negative of the batteries for safety reasons. This in turn means that all of your bonded fittings, such as the drain plug, are electrically connected to the AC 120 volt grounding conductor. When you feel the tingling it's because you have some slight leakage (or low resistance connection) between the neutral conductor and the grounding conductor somewhere on your boat with the AC equipment that is turned on when you feel the tingling.

Things get a little weird when you are at a house plugged in to your boat on a trailer. In your house the neutral is connected to the ground in your electrical panel (and thus also at the outlet at your house that you're plugged into), and also out in the yard where the ground bar is in the physical ground where the power comes in your house.

Your ELCI shore power breaker is there to prevent dangerous currents on the shore power grounding conductor. It's designed to trip at 30 milliamps, which is the level that can kill someone. Regular GFCI outlets usually trip around 6-7 milliamps although they advertise 5 milliamps. You can feel a tingling at just 1 milliamp of current. What I suspect is that you have some low resistance neutral to ground connection somewhere in the AC system on your boat that is delivering that 1 or 2 milliamp of current on the grounding conductor, that for whatever reason is not going back to your house on the shore power cable that you hooked up. Instead it is shorting through you to ground when you touch any of the bonded equipment on the boat.

On the positive side, as long as your ELCI is working, it shouldn't kill you and will trip the ELCI before that happens.

I would look at the grounding plug at the point it plugs into your source at your house. With it disconnected from power, measure resistance from that ground prong to the ground point (female connection) on your shore power plug that connects at the boat. You should have no resistance. If it shows open, than you don't have a path for ground back to your house (the source of power).
 
Rode Trip said:
Are you using a 3 prong grounded outlet and connections or just a two prong (hot and neutral) plug somewhere between your boat and power source?

It's a common problem in boatyards that don't have grounded electrical outlets. The boats (ABYC compliant boats) are wired with the AC grounding conductor connected to the DC negative of the batteries for safety reasons. This in turn means that all of your bonded fittings, such as the drain plug, are electrically connected to the AC 120 volt grounding conductor. When you feel the tingling it's because you have some slight leakage (or low resistance connection) between the neutral conductor and the grounding conductor somewhere on your boat with the AC equipment that is turned on when you feel the tingling.

Things get a little weird when you are at a house plugged in to your boat on a trailer. In your house the neutral is connected to the ground in your electrical panel (and thus also at the outlet at your house that you're plugged into), and also out in the yard where the ground bar is in the physical ground where the power comes in your house.

Your ELCI shore power breaker is there to prevent dangerous currents on the shore power grounding conductor. It's designed to trip at 30 milliamps, which is the level that can kill someone. Regular GFCI outlets usually trip around 6-7 milliamps although they advertise 5 milliamps. You can feel a tingling at just 1 milliamp of current. What I suspect is that you have some low resistance neutral to ground connection somewhere in the AC system on your boat that is delivering that 1 or 2 milliamp of current on the grounding conductor, that for whatever reason is not going back to your house on the shore power cable that you hooked up. Instead it is shorting through you to ground when you touch any of the bonded equipment on the boat.

On the positive side, as long as your ELCI is working, it shouldn't kill you and will trip the ELCI before that happens.

I would look at the grounding plug at the point it plugs into your source at your house. With it disconnected from power, measure resistance from that ground prong to the ground point (female connection) on your shore power plug that connects at the boat. You should have no resistance. If it shows open, than you don't have a path for ground back to your house (the source of power).
Click to expand...
Great info Rode Trip.
I will do that.
I’m pretty sure it is all three prong with an adapter that attaches to my 30 amp shore power cord.
I used an outlet tester that plugs into the outlet and got a green light which I think tests the grounding but I’m not sure.
This outlet is from our detached garage that is fed by one 10g underground cable from the house breaker box.
 
Moosewood said:
Great info Rode Trip.
I will do that.
I’m pretty sure it is all three prong with an adapter that attaches to my 30 amp shore power cord.
I used an outlet tester that plugs into the outlet and got a green light which I think tests the grounding but I’m not sure.
This outlet is from our detached garage that is fed by one 10g underground cable from the house breaker box.
Click to expand...
Latest update.
I hadn’t noticed before but the reverse polarity light on the electrical panel is on in the boat. I’ll test that on my house outlet and also the converter plug to see what’s up.
 
Latest update.
Discovered I had bad power at the building. Hot wire was 70v and neutral wire had 50. Discovered splice underground was failing. All patched and fixed. Thanks all!!!
 
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