Shocked through the Props - resolved

S

sunshinedaydream

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Joined
Jul 2, 2007
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27152
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117
RiverRat had it correct. Reversed Polarity caused by a non-grounded extension cord plugged in upside down. Not my proudest moment. Marine Electrician went over everything while he was there and solved a couple of small issues I was having with switches on the bridge so not a total loss. Splashed today with confidence. Word to the wise if you have a cord with the ground snapped off, fix it or throw it out!
 
How can you get a shock by touching the prop and shaft at the same time? Aren't they connected together through metallic contact?

In any event, there is something wrong here and I would disconnect the electricity from the boat until this can be fixed. You could hurt or kill someone.

Bring in an electrician.
 
Typo i meant if i touch the prop or shaft. Boat is unplugged batteries as well electrician comming on wed.
 
I don't understand your last post. "Typo i meant if i touch the prop or shaft. Boat is unplugged batteries as well electrician comming on wed."
 
I don't understand your last post. "Typo i meant if i touch the prop or shaft. Boat is unplugged batteries as well electrician comming on wed."
 
OK, you get a shock from touching the prop or shaft while standing on the ground, right? That makes sense, but it indicates a problem. The problem could be in your boat, the supply to the power cord, or the cord itself. The prop and shaft should be at the same potential as the ground you are standing on. Then you wouldn't get a shock. Your electrician should be able to find and correct the problem.
 
Investigate problem and get it fixed ASAP before putting in the water. There should not be voltage on any underwater part.
 
I think he means he gets a shock from touching either the shaft or prop, that the boat is unplugged from shore power, the batteries are either turned off or disconnected and an electrician is coming by to check things out on Wed.
 
Getting ready for launch this weekend I was sandingcleaning the shafts and props. As I was doing this I was running the battery charger through the 110 adapter through my dockside input

bad cord, bad charger, bad/no ground,reversed polarity
 
Marine battery charger?

I'm not much on electronics, but I hear something like the Marine chargers have Isolation Transformers and homeowner car charges have an Autoformer.
 
Apologize for the confusion. I received an eletric shock while touching my prop. Boat is on the dry at the marina. I had a extension cord pluged into the yard power. Then through a 110 converter to my dockside power. On board battery charger on,through the panel the same that would be on at the slip. Will let you know what i find.
 
quote:
Originally posted by j-d

Marine battery charger?

I'm not much on electronics, but I hear something like the Marine chargers have Isolation Transformers and homeowner car charges have an Autoformer.

Click to expand...


Any charger should have a transformer to isolate the output from the input. If there is a direct connection between the two, get rid of the charger and cut the cords off so nobody can use it. It could be lethal on water or on land.
 
Same thing happened to me in the past. I was using an old extension cord that was plugged into a shore power adapter. The extension cord had the ground prong cut off so it could fit a two pronged receptacle. Unplugging the extension cord, rotating and plugging it back in solved the problem. I think you are experiencing reversed polarity.
 
Look at the neutral wire on the cord or in the plug you are plugged into. Sounds like you may have lost it or have a bad connection.
 
Probably an automotive charger. They are cheaply made with one side of the transformed grounded. That's why they can ruin running gear on boats in the water.
 
I'd also test the yard's power to make sure wires are not crossed. I bet if ou use a gfci, it would trip.
 
Any more details on the boat, does it have isolation transformer ( probably not), galvanic isolator (maybe), polarity indicator ( probably), generator, water heater?

Do you have an ohm meter? Most likely something on board is leaking neutral to ground, which is not a good thing, but not in itself a disaster. Combine it with poor neutral connection to the legit ground, it could become a disaster. With you boat NOT plugged into shore power but the shore power cord plugged to your boat, the generator switch ( if so equipped) set to shore power, and all A/C breakers turned on - put one lead from your ohm meter on the neutral prong of the shore cord, and one one the ground prong. If you aren't showing on open circuit - infinite ohms, or near to it, you have a neutral to ground leak on board. I did this exercise years ago, and had many - water heater, defective 120/12 combination interior lights, and believe it or not light bulb that previous owner wired as polarity indicator on the panel. No wonder I showed 120 volts from the prop shaft to the ground, and got zapped every time i climbed onto the boat. Luckily I never killed anyone swimming near the boat when had shore power turned on.

Nigel Calder's book 'Boatowners Mechanical and Electrical Manual' was priceless in finding my leaks. Most critical is that A/C ground is tied to DC ground, and A/C neutral is not tied to A/C ground ( unless set to generator).
 
quote:
Originally posted by alk

Any more details on the boat, does it have isolation transformer ( probably not), galvanic isolator (maybe), polarity indicator ( probably), generator, water heater?

Do you have an ohm meter? Most likely something on board is leaking neutral to ground, which is not a good thing, but not in itself a disaster. Combine it with poor neutral connection to the legit ground, it could become a disaster. With you boat NOT plugged into shore power but the shore power cord plugged to your boat, the generator switch ( if so equipped) set to shore power, and all A/C breakers turned on - put one lead from your ohm meter on the neutral prong of the shore cord, and one one the ground prong. If you aren't showing on open circuit - infinite ohms, or near to it, you have a neutral to ground leak on board. I did this exercise years ago, and had many - water heater, defective 120/12 combination interior lights, and believe it or not light bulb that previous owner wired as polarity indicator on the panel. No wonder I showed 120 volts from the prop shaft to the ground, and got zapped every time i climbed onto the boat. Luckily I never killed anyone swimming near the boat when had shore power turned on.

Nigel Calder's book 'Boatowners Mechanical and Electrical Manual' was priceless in finding my leaks. Most critical is that A/C ground is tied to DC ground, and A/C neutral is not tied to A/C ground ( unless set to generator).

Click to expand...


He has an electrician coming to check it out and that's the simplest and most reliable way.

Lacking that, the first thing I would do is break out my handy dandy $10 outlet tester from the home center and starting at the marina outlet, dock pedestal. etc., check the polarity and ground.
 
Just make sure it's a marine electrician who is looking at the boat; there's that one significant difference that a 'shoreside' electrician would possibly miss ( neutral not tied to ground on the boat).
 
quote:
Originally posted by sunshinedaydream

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RiverRat had it correct. Reversed Polarity caused by a non-grounded extension cord plugged in upside down. Not my proudest moment. Marine Electrician went over everything while he was there and solved a couple of small issues I was having with switches on the bridge so not a total loss. Splashed today with confidence. Word to the wise if you have a cord with the ground snapped off, fix it or throw it out!

Click to expand...


Non-grounded I've got. How could you plug an extension cord in upside down? The blades are different widths and have been for decades. Grounded or not, the cord should only be able to go in one way.
 
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