Shore power possible short

H

Hunkydory

New member
Hope someone has an obvious answer to this that I'm missing.

Yesterday while I was changing the moter lower unit fluid I at times noticed an unpleasant tingling burning sensation when just brushing the moter with my hands. The boat is put up for the winter on the trailer and the trailer on blocks. The shore power was plugged in to top off the battery. The tingling would stop when the shore power plug was turned off. Our home is the old style only two wire one being ground system. Could this be the cause and I just need to ground the boat or is a short somewhere the likely problem.

Jay
 
Charlie

The boat shore power is 3 wire, so no problem when at a slip and connecting into shore power with the boat in the water or at least there wasn't this summer when I was hooked up a lot at the Bridge Bay Marina slip on Yellowstone Lake. Its the old home and its two wire system that I think may be causing the problem on the boat. I just don't know enough about it to be sure. Know one thing and that's the tingle could turn into a bad bite, so here I am looking for help.

Jay
 
Jay-

Some questions:

Do you experience this same type of problem inside the house or when using any other outdoor tools on extension cords?

Does the outlet from the house have one plug in connector longer (wider) than the other?

Does your extension cord have one connector longer (wider) than the other?

Are you using a three prong adaptor on the extension cord that has a green wire ground that is designed to be screwed into the outlet center screw for a ground? Is it connected?

Can your shore power cord adaptor from the boat be plugged into the extension cord either of two ways, reversing the polarity in effect?

Does your shore power system have a GFI Ground Field Interrupter circuit in it? Has it tripped at all?


Is the battery charger hard wired to the 12 volt circuit or plugged into a wall socket? Can the leads be inverted on the 120 volt side?

If you place a digital voltmeter between the motor and a grounded rod into the soil, how many AC volts does it read? BE CAREFUL HERE, THE VOLTAGE BETWEEN THE MOTOR AND THE GROUND MAY SEEM A LOT MORE WHEN USING A FULLY GROUNDED ROD!

Is there any chance that any of the return ("grounded") side of the circuit is poorly connected , giving a weak ground/return path?

Place the digital voltmeter between the grounded side and the rod out at the boat and see if there's any apparent voltage.?????


Thanks all for now, gotta go, be back later!

Joe. :teeth :thup
 
You know, I have the same problem with Journey On when it's at home and on the trailer. I use only a 2 wire system to the boat, power and return, no earth (green) wire The motor's a Honda, and I don't know how 110 VAC gets to the motor. However, I've got a shock or two that catches one's attention.

What I'm going to try is to use a local earth, since the green wire goes directly to ground (as does the white wire, eventually.) My only reluctance is how it'll affect the GFI in the garage.

I'd still love to hear how the motor gets 110 VAC on it. Then I'd be happy. The only place where the 12 VDC and 110 VAC come into contact is the inverter and battery charger. The inverter is off by a switch, and I don't know about the Xantrex charger.

Boris
 
Joe

No problems ever in the home or when using other tools in the past. Though have been told that's the problem with the old two wire system without the third direct ground wire it doesn't have the built in safety net.

The outlet from house that I'm using to connect to the boat is actually a two prong outlet in my shed run from a breaker in the house. Yes it does have the one outlet wider than the other and if I understand it correctly that is for polarity.

My extension cord is a 30 amp Marine cord from West Marine that I must use a two prong adapter to connect to shed outlet.

No there is no connection with green wire. Just Marine cord adapted to plug into the two prong.

No I cannot reverse the polarity at the boat, but would be simple to do at the outlet. Would even be simpler if I had a polarity checker.

Don't know if I have ground field interrupter in the shore power circuit, but do know breaker hasn't tripped and if I turn the breaker off and leave power connected to the incoming connector to the boat it doesn't tingle at the moter.

The battery charger is built into the shore power system with its own breaker and automatically charges the batteries if needed and at the time I was servicing the moters it was needed.

My youngest son has my volt meter at his place, so may take a bit to make voltage test between ground and boat, but i will.

Could be a chance of the return being poorly connected. Will have to check.

And the thanks is all to you,

Jay
 
I've experienced the same problem when my boat is on the trailer and plugged into a circuit in a shed 100' from my main panel. I found that if I turn off the breaker to the battery charger the problem disappears. I don't (thank God) experience the same problem when my boat is suspended in the lift and plugged in with me standing in waste deep water beside it. My dock power is well grounded so I can only assume the stray voltage is being directed to the ground through the grounding circuit rather than through me! I don't have ground fault protection circuits at either location. The ground resistance at the shed location is pretty high so I suppose I make a better ground as when I notice this the ground is usually wet from me washing the boat. Why I have this stray voltage is a mystery to me as I also have a galvonic protection device. I have a portable GFI that I plan to use in the future. What I experience is more of a tingle rather than and AC type shock.
 
Well, Boris and Marvin, If may not be good to you, but I'm happy to know there are at least three of us in the same boat so to speak still surviving. Yes now and again it does get your full attention. I'm glad yours stays only a tingle Marvin.

Jay
 
I don't think GFI's will do you any good if you are using a two wire cord from it to your boat. In my case I think I simply don't have a good ground in my shed. Either way something isn't correct and I suspect the battery charger. Mine is a factory installed Guest. My plan is to drive and earthen ground close to where I store my boat on land and measure the voltage between the motor and the earthen ground and perhaps find if it's AC or DC potential and how much. This is a little embarrasing to admit but I spent 40 years working as and electrician so my tolerance may be a little higher than most, I've been shocked a lot! :shock:
 
Yikes!!!!! Just measured from motor to ground and its a full 110 VAC. Through all those tingles and burns I'd been standing and kneeling in water saturated ground from running the motors before working on them. My nerves must not be conducting at my present age like in the past. My charger is a Guest mounted at the factory like Marvin's and when I tripped the charge breaker no voltage then from the motors to ground. Marvin at least with your experience you're making me feel a little bettor for not being able to solve this on my own

Jay
 
There is a good chance, that the black and white wire are reversed at the plug, or somewhere in the circuit. I have found that with long runs to my lifts in the past, that there was some voltage leakage--and that ground potential was not the same at the boat lift, as at the meter box (where the circuit--neutral and ground--are tied to ground. My "cure" was both to put in new wire, in dry conduit (probably not your problem), and put a second ground rod at the lift. The green wire was tied to this rod. You could put in a ground rod near the extension cord and ground that.

My worry would be the possibility of electrolysis of the motor, if it were submerged with these conditions. (as well as potential injury to the boat owner).

I don't know if these C Dories have the galvanic isolators, or not. My 25 does not have it, the Tom Cat does. ABYC I believe requires the galvanic isolator.

There is also the possablity that you are getting pulsed DC at 14 volts thru the battery charger--to the ground of the battery (and the motor). Because the battery charger does not have its green wire (ground) attatched, the pulse is now going through your body to ground. The question is how good is the ground isolation (shoes worn?--as Joe suggests--if you have the ground rod and then hold it, and touch the engine, there may be a lot more current flowing, where you are isolated to a reasonable extent with shoes on--but if you are kneeling on wet ground--that will have a more conductive effect than standing.

Check the voltage first--see how much AC and DC voltage there is from the engine to ground. Take the ground point at the battery, since that will be connected to the engine, and you can clamp a lead on there. Consider putting a 3 wire circuit to the boat--a ground rod near the outlet in the shop/garage, and perhaps looking into a galvanic isolation circuit--especially if the boat is left in the water.
 
Hunkydory":mlnuuvpx said:
Yikes!!!!! Just measured from motor to ground and its a full 110 VAC. Through all those tingles and burns I'd been standing and kneeling in water saturated ground from running the motors before working on them. My nerves must not be conducting at my present age like in the past. My charger is a Guest mounted at the factory like Marvin's and when I tripped the charge breaker no voltage then from the motors to ground. Marvin at least with your experience you're making me feel a little bettor for not being able to solve this on my own

Jay
Click to expand...

Wow now thats scary. No idea what my voltage is boats presently in the lift. Like Bob my boat lift is 1,000 from the service ground and I added a second ground for the lift at the dock. On a long run like that the ground wire resistance could easily be higher than your body resistance standing in water. What I felt was more like low voltage pulsating DC I was barefoot standing in wash water. I'll be checking mine tommorrow. My boat has the factory installed galvonic isolater I'd assume if it's properly wired it would eliminate the problem?
 
We must have double posted...if it is 110 volts, then the neutral and ground are reversed somewhere in the circuit--most likely at the plug in the garage, but it could be in the boat (stranger things have happened). There a direct connection between the neutral (white wire) and gound somewhere on the boat. You need to trace this out--I would check the plug first...and work from there, plus put in a ground to the boat circuit.
 
Hi folks,
This thread highlights one of my concerns about boats, electricity, and stray currents in marinas. A few days ago somebody asked about leaving their boat plugged in to shore power for five months. I was going to post a reply, but thought why start a ruckus. When you plug into a shore power system your boat can become part of the whole circuit with all the other boats through the power system and the water. Some of those boats are likely wired by amateurs or even professionals who shouldn't even do house wiring, let alone marine systems. If one is close by, your boat, or you, can wind up being the ground path for somebody's crummy wiring job. I don't even like to be in the water in marinas because of the potential for stray currents. Be careful, there are lots of hot marinas wth bad galvanic corrosion problems.

Best of luck,
Mike
 
Tried rechecking voltage at motors to ground with power coming from a different source then the house. No voltage from motors to ground, then hooked back up to house and wouldn't you know no voltage from motors to ground now there either. The only difference being the batteries are now charged. Could this wayward current be coming only from the charger to motors while it is actually in the process of charging batteries. Also noticed the shore power breaker box has an incoming correct polarity check and its ok.

Jay
 
Jay it sure sounds like you had your polarity reversed when you read 110 volts to ground. Are you using the same cord and adapter for all these tests and are they in good shape. Thats a really dangerous situation you described before. I'd try to find or install a good 20 Amp properly grounded circuit and start further tests from it. Seems if it was a problem with the boat it would have surfaced before now. I suppose the battery charger could be shorted but I would think that would fry your batteries pretty quickly.
 
Is the battery charger shut off, or just on trickle charge? (what is the DC voltage of the batteries with the charger on?)

Some reverse polarity lights will not come on if there is no "green wire"--or ground. Or it may have flicker if there is no ground such as with an inverter or the Honda gensets.

I would still ground the boat's AC electrical system, preferably with a ground rod near the power supply or the boat. I have never seen a properly working battery charger put out 110 volts. But I suspose that at very low amperage, there could be a leak...
 
Marvin & Bob

Cord and everything else is exactly the same only difference being the battery charger is in the float sequence where it is maintaining a charge by slowly dropping from 3 amps to .1 amp which is its lowest charge maintain output. Will draw down the batteries tonight and see it goes back to the the 110 AC from motors to ground tomorrow when I try charging again.

If this can't be solved before winter overtakes me and that's coming soon will do as you suggest Bob and ground the boat's AC electrical system.

Sure wasn't considering the gen set or inverter wasn't really grounded either.

Thanks for the help,

Jay
 
The charger should be wired to the 12V ground. If there is an internal
leak of 120V -> 12V ground in the charger, you could be experiencing this
problem. Assuming the wiring is correct, the leak would have to involve some
resistance, otherwise the 120V breaker would trip.

Mike
 
Hunkydory":kf00ov3h said:
Tried rechecking voltage at motors to ground with power coming from a different source then the house. No voltage from motors to ground, then hooked back up to house and wouldn't you know no voltage from motors to ground now there either. The only difference being the batteries are now charged. Could this wayward current be coming only from the charger to motors while it is actually in the process of charging batteries. Also noticed the shore power breaker box has an incoming correct polarity check and its ok.

Jay
Click to expand...

Jay-

Your explanation sounds logical to me.

Check to see that threre is NO CURRENT flowing to batteries when they are charged (might be a "float" charge level curent to keep them topped off in some chargers.)

Use some of the battery charge somehow and test again when charger activates the larger charge current to see if motor becomes "hot " again.

Are there TWO charging circuits, one for each battery? Do you get the same result from each one or with one at a time disconnected?

Can you measure 110 VAC from either of the + or - output terminals to the ground with the charger connected and charging? (Almost the same as the last paragraph test.)

Sounds like the charger has a short between the primary and secondary transformer coil wires (internally, of course).


Call Guest or whoever the charger manufacturer is and ask for their technical representative and present all the evidence to him/her. Tell them you're getting shocked, and maybe their liability may influence their warranty coverage.

Any chance the charger is still under warranty?

Good Luck, and let us know how it comes out!

Joe. :teeth :thup
 
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