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Old 03-13-2017, 10:43 AM   #1
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Question Reverse polarity

Reverse polarity
I have a 2006 Mainship pilot 30 W/ 315 Yanmar. I got a call from my brother in law saying my winter tarp / cover had split and I needed to come down to the marina. I went to marina to find the tarp destroyed from the recent heavy winds in Maryland. I took down everything and put up my canvas to try and protect the cock pit for the winter storm arriving tonight. Once complete I plugged in the boat and got a reverse polarity light at the panel below. I look at the marina receptacle it was plugged into and it had been changed to a GFI within the last couple weeks. I called the marina and they stated they did replace it and checked it with a tester and said the electric is fine.
Do we have an electrician out there that could give me advice on what to start looking at on the boat to determine the problem. What would cause this to occur while on the hard at the marina. Other than losing the tarp and the new receptacle at the marina nothing has changed. The boat has been on the hard since November. This is the first time I ever saw this light illuminated.
Thanks Jeff.
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Old 03-13-2017, 10:50 AM   #2
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First, unplug your boat from the pedestal and plug it into a different one. Try several if you have to.


The marina did some electrical work. You did not. If there's a problem, it pretty much has to be something they did.
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Old 03-13-2017, 10:53 AM   #3
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Test the marina's outlet yourself before going at your boat. Your chance to buy a new toy; this one will test the GFCI as well as the other functions.
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Old 03-13-2017, 11:03 AM   #4
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Yes get your own tester at home depot etc. they aren't expensive.
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Old 03-13-2017, 11:05 AM   #5
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Originally Posted by DHeckrotte View Post
Test the marina's outlet yourself before going at your boat.
That won't work on the 30 or 50 amp boat outlet.

It will work on one of the boat's outlets and should agree with the boat's reverse polarity indicator. If it does, the marina has a problem. If it doesn't, some mice have been doing electrical work while the owner was away.

What we aren't clear on of course is, are there any extension cords involved? Any adapters? Any repairs to the shore power cord in the meantime?
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Old 03-13-2017, 11:30 AM   #6
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That won't work on the 30 or 50 amp boat outlet.
Why not? I think he's talking about a boatyard outlet, not a dock pedestal. Those are, I think, normally 20 amp 110v.

If he were talking about a 30 amp 110v dock-style pedestal all he'd need is the 30 to 15 or 20 amp adapter.

And if he were talking about a 50 amp 220v dock-style pedestal, he'd need the wye adapter plus the 30 to 15 or 20 amp adapter. But I think you could not have wrong polarity in the 220v setup; it would instantly trip the marina's panel breaker.
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Old 03-13-2017, 01:23 PM   #7
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This problem was discussed on a couple of recent threads, the most relevant is this one- Big Marina Rewire & the new code. Your boatyard replaced the power receptacle (probably a 15A or 20A) with a GFCI protected one as required by current electrical codes.

Your boat may have a simple incandescent light bulb for reverse polarity indication that passes enough current to trip the GFCI. It may also be a ground fault inside your boat, but normally that wouldn't show reversed polarity.

If it is the reverse polarity lamp, you can replace it with a 120V LED (Paneltronics and Blue Sea sell them among others) and it should keep the current low enough not to trip the GFCI.

If it is a ground fault inside your boat, then you will have to track it down and fix it. Lots of ways were discussed in the thread above.

And finally I don't know of any yard that will let you keep power connected to your boat while it is on the hard.

And really finally, if the marina has also installed GFCIs at the slip power pedestals, you will have the same problem when your boat is launched and plugged in at your slip.

David
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Old 03-13-2017, 01:45 PM   #8
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He seems to be talking about his boat indicating reversed polarity, not a GFCI tripping. The most likely cause is, the marina reversed the polarity when installing the new breaker. Nothing has changed on his boat. It used to be fine, the marina did some electrical work and now there's a problem.


To me, at least, the logical troubleshooting step is to check the polarity from the marina's outlet. It there's an extension cord involved and it has been repaired at some point, there's a good chance that's where the problem lies. I have known people who don't understand the importance of following the color code.
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Old 03-13-2017, 02:01 PM   #9
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Gentleman,
Just to clarify
The new GFI outlet is on a wooden 4x4 in the yard next tomy boat, which is on the hard. Not sure if this is a 20amp circuit or not. It isnot the pedestal at the slip. The last time I was at the boat in December Iplugged into the same circuit and wascharging my batteries while working on the boat. I have a heavy duty 25 foot extension cord from the boat to thereceptacle. I have a three way plug at the end so I can plug in the boat andadditional lights if needed. Everything worked fine. I have read the otherthread and I do have the tester shown in my garage. I spoke with the marinathis morning and they stated they checked it out today and it tested fine andis wired properly. That makes me believe it may be the boat? I will check tosee where the next available outlet is. The problem is I will need a heavy dutyreal long cord to check it out. I was thinking about taking a small portablegenerator, Honda type and plug the boat in and see if I get the reversepolarity light. While I may get a grounding issue with the galvanic isolator itshould show me if it's the boat or the marina.
I'll do some leg work and get back with you. Will be shovelingsnow over the next day or two so I will not get to it until this weekend.
Thanks for the suggestions.

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Old 03-13-2017, 02:08 PM   #10
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Quote:
Originally Posted by DHeckrotte View Post
Why not? I think he's talking about a boatyard outlet, not a dock pedestal. Those are, I think, normally 20 amp 110v.

If he were talking about a 30 amp 110v dock-style pedestal all he'd need is the 30 to 15 or 20 amp adapter.

And if he were talking about a 50 amp 220v dock-style pedestal, he'd need the wye adapter plus the 30 to 15 or 20 amp adapter. But I think you could not have wrong polarity in the 220v setup; it would instantly trip the marina's panel breaker.
yep...they will work with the right adapter on 30 amp dock pedestal power...I do it all the time and works like advertised.

Not sure on 50A 125/250 as different adapters are wired differently.
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Old 03-13-2017, 02:26 PM   #11
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Originally Posted by jskinner30PII View Post
Gentleman,
Just to clarify
The new GFI outlet is on a wooden 4x4 in the yard next tomy boat, which is on the hard. Not sure if this is a 20amp circuit or not.
Does it look like a boat outlet or does it look like the outlets in your home? If it looks like the outlets in your home, buy the tester shown and plug it in. Compare the results to the printing on the tester.

Quote:
I was thinking about taking a small portablegenerator, Honda type and plug the boat in and see if I get the reversepolarity light.


That won't tell you anything unless the neutral and ground are tied together at the generator. "reversed polarity" has to be referenced to ground. Without tying the neutral to ground, the two wires have nothing to reference to except each other.

Normal polarity has the black "hot" wire at 120 volts to the white "neutral" conductor and the green "ground" conductor. "Reversed polarity" means that the white wire is hot and the black wire is neutral or at ground potential. This is a danger, that's why you have the reversed polarity indicator in the first place.

Plug your tester into the marina outlet. If it shows everything as being how it should be, plug it into the end of your extension cord. If it tests OK, move on to the next junction. Keep moving along the power path until you find the problem.

As I tried to point out earlier, it's unlikely that anything changed on your boat unless someone was doing electrical work on it.


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Old 03-13-2017, 02:44 PM   #12
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Most likely a standard looking GFI that you plugged an extension cord into is either 15 or 20 amp....20 amp plugs just have one blade turned sideways...so a standard extension cord fits either as the receptacle has that slot both vertical and horizontal.

There are 20 amp twist lock fittings...but I have never seen a GFI one....but some marinas do have them. You can't plug an extension cord into one without an adapter.
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