Shore power shock felt from ladder

[OrangeCrush]

While plugged in to shore power and charging in the yard, I felt some current coming from the stanchion into my hand as I was standing on the ladder. I immediately unplugged the extension cord from the outlet. Everything else appears normal and all connections look good. Is this a problem with my wiring or the boatyard’s? How might I troubleshoot this? Thanks

[senormechanico]

Quick and dirty way would be to measure AC voltage (also DC) from the ground terminal in the shore power pedestal, one lead of the meter in the socket, and the other the water.
Then try from the neutral lead to the water.
Ideally, there should be zero voltage.
Use a short lead of scrap wire in the water and measure the end on the dock.
If you put the meter lead in the water, rinse it thoroughly afterward !

Make a record of what you find, then repeat with the boat plugged in.
Measure from your ladder to the water and let us know what you find.

[OrangeCrush]

My boat is out of the water at the moment and I was climbing up to it on a ladder. My feet were soaked and the ground at the base of the ladder was wet. The boat was plugged in and charging by way of a long extension cord to a power pole. Another live extension cord was hanging off my boat onto the ground. The ground where the second cord was lying was also wet but not a puddle.

[bill martin]

Originally Posted by senormechanico

Quick and dirty way would be to measure AC voltage (also DC) from the ground terminal in the shore power pedestal, one lead of the meter in the socket, and the other the water.
Then try from the neutral lead to the water.
Ideally, there should be zero voltage.
Use a short lead of scrap wire in the water and measure the end on the dock.
If you put the meter lead in the water, rinse it thoroughly afterward !

Make a record of what you find, then repeat with the boat plugged in.
Measure from your ladder to the water and let us know what you find.

Turn off the power on the shore box (dock box). Talk to a professional electrician about where a GFCI Ground Fault Circuit Interrupteur could be installed. If you are in an unfriendly Marina realize they have pre existing non conforming rights.
Their installation was built properly with permits 40 or 50 years ago and they are not required by law to update their system. That being said you do not want to get yourself fried. A GFCI is a two up plug that simply detects electricity going to ground in an unsafe way and shuts the circuit off. Better no electricity
than dead!
I put a weatherproof exterior electric box with a GFCI plug in my 30 foot power cable where it twist locks into the 20 amp circuit breaker at the dock box. I put another GFCI in the first in line standard AC outlet in my boat. Double check to see if other plugs have coverage from the first GFCI. If they don’t just change the thirty year older plugs that doesn’t pass the test to another GFCI outlet. Any hardware store will have a little red plug in ground fault tester for $2 While you at it double check that all of the outlets in your house that are within an arms length of faucets have GFCI outlets, all exterior plugs, all garage outlets. Any place there is any chance of ground fault going through your heart is especially dangerous. I have had a long conversation with a guy who was carrying an aluminum ladder in his back yard and inadvertently touched the wires that serve the garage. He was fried luckily down his right side so his heart escaped serious damage. I am a retired residential building inspector for the city of Los Angeles.
Accidental groundings are big deal.
Swimming pools and fish ponds with pumps also have huge issues.

[Zil]

Lot of bad information here. The ground, green, side of the pedestal or your extension cord is bad. Or it could be in your boat. Use your volt meter to check hot to neutral to ground at the out let.
GFCI tests the difference in voltage between the neutral and hot sides of ac current. They will work even without a ground. It is a Good Idea to have GFCI or even the newer versions on your stuff.

[SSgtPitt]

A good hardware / home improvement store will sell a GFCI device for your extension cord.
I use them when I’m cutting tile with a wet saw.

[chris95040]

Originally Posted by Zil

Lot of bad information here. The ground, green, side of the pedestal or your extension cord is bad. Or it could be in your boat.

I don't think a bad green (ground) alone would cause a problem - it's a safety feature in the event something *else* goes wrong and energizes the conductive case of a device, for example. Certainly something you'd want to fix if it were broken, but shouldn't be the cause of this fella getting zapped.

I'm a big fan of GFCIs. If your outlets at your marina have "test" and "reset" buttons, and they work, then you are looking at GFCIs. If not, get an inline one the plugs in between the outlet and your extension cord. And if it's tripping, figure out what's broken.

[OrangeCrush]

Thanks, all. This stuff is complicated but I’m learning. It turns out that it was a bad outlet in the yard. The outlet showed 120 volts on a multimeter between the two prong holes, but each also showed about 60 volts when connected to the third ground hole. It’s my understanding that the small one (hot) should show 120 volts and the big one should show nothing when connected to the ground, so presumably there is some bad connection in the yard’s electrical system and both prongs were hot. So with some reversal of polarity, everything bonded on my boat became hot, including the lifelines, and the current was eager to find the ground through myself and the ladder.

They taped off the outlet box and they’re going to have their electrician look at it. The other nearby outlets tested normally with a multimeter.

If anything I said doesn’t make sense please let me know!

[senormechanico]

I missed the part in the original post about being in a yard.
As Carsten said, it could still be your cord or boat's wiring.

[OrangeCrush]

Originally Posted by chris95040

I'm a big fan of GFCIs. If your outlets at your marina have "test" and "reset" buttons, and they work, then you are looking at GFCIs. If not, get an inline one the plugs in between the outlet and your extension cord. And if it's tripping, figure out what's broken.

No GFCIs in the yard but getting an in-line one for my extension cord sounds like a very good plan. I’m sure the problem I stumbled upon is not the only imperfection here.

[waterman46]

You did good by helping the yard find a potentially deadly problem.

How strong was the electric sense when you touched the stanchion? If you just got a "tickle", rather than a shock, from the stanchion then it may have been due to the "floating" (non-existent) ground connection of the ground terminal in the yard's outlet box, combined with the effect of the long extension cord. In a long wire run, a small amount of energy from AC voltage in the hot wire is inductively coupled to the ground wire (and even from the hot to the neutral). If that wire is not actually grounded somewhere, this coupled energy will cause a voltage to appear in the wire. The extension cord ground wire was connected to your boat's ground, and so to the stanchion that you grabbed. As long as you don't have any faults or excess leakage in your boat's AC wiring, you would feel a voltage on the stanchion but won't get a lethal shock because the inductive coupling is rather weak at only 60Hz and maybe 100 ft of cable. The weak coupling cannot supply enough power to be felt as a true shock.

Of course it was a bad idea to have that other hot power cord hanging off your boat onto wet ground, and the wet shoes(if ladder was metal), well it's just asking for trouble.

[Cadence]

Originally Posted by OrangeCrush

My boat is out of the water at the moment and I was climbing up to it on a ladder. My feet were soaked and the ground at the base of the ladder was wet. The boat was plugged in and charging by way of a long extension cord to a power pole. Another live extension cord was hanging off my boat onto the ground. The ground where the second cord was lying was also wet but not a puddle.

Get the second cord off the ground. Either there is no GFI or there is an open ground someplace such that is not letting the GFI trip.. You don't have extension that someone has cut the ground prong off the male side?

[OrangeCrush]

Point taken about keeping things dry, it’s a cautionary tale overall. But the second cord was coming from my boat’s outlet which is gfci protected, and it wasn’t actually wet. I included that detail in case it was related but at this point I don’t think it was related to the shock.

The sensation was as if my hand fell asleep instantly.

[Cadence]

I guess we can assume the ladder is grounded and you were to it. What else had you touched?

[Rockyscience]

FYI folks, a GFCI senses the current on the hot (120v) and the neutral if it is more than 7 milli-amps difference it trips, it does not look at grounds at all. ( forgot difference in 1st post)