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Old 16-01-2016, 09:10   #1
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GFCI plug question

We just bought a new boat, and one of the survey findings was that most of the outlets aren't GFCI protected, and the one that is isn't working properly. Now I've added GFCI outlets in the galley with no problems, but I'm still trying to figure out the one that's not working properly.

Here's the issue; If you push the test button on the outlet, it trips with no problem. But I also bought one of those outlet testers with the 3 lights on it. When I plug this into the outlet it indicates correct wiring, but when I press the test button it doesn't trip the outlet, instead it indicates hot and neutral are reversed.

I know hot and neutral aren't reversed, I've visually checked and double checked with a multi-meter. Also, at first I thought it was just a faulty GFCI plug so I went ahead and replaced it, but the new plug indicates the same thing.

I've read that if the GFCI outlet is ungrounded (2 wire vs 3 wire), then the tester may indicate something is miswired and fail to trip the outlet, even though things are working properly. However, this is a grounded outlet, and if I'm not mistaken, the ground is connected. With the multimeter, I'm measuring voltage between hot and ground; If the ground were not connected, I shouldn't measure any voltage between hot and ground, correct?

Does anyone have any suggestions as to why the tester won't trip the outlet?

This actually brings up a 2nd question. When I measure voltage between hot and neutral, I'm getting 120v (which is what it should be). However, if I measure voltage between hot and ground I get ~85volts, and I get ~35 volts between neutral and ground. I know I should have some voltage when measure across neutral and ground, but most of what I've read seems to indicate it should only be a few volts. Is 35 volts too much? If so, what could be the cause? As a note, this is the case for all the outlets on the boat, not just the GFCI I'm trying to figure out.

Thanks for any help
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Old 16-01-2016, 09:24   #2
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Re: GFCI plug question

Quote:
Originally Posted by blinkerfluid View Post
We just bought a new boat, and one of the survey findings was that most of the outlets aren't GFCI protected, and the one that is isn't working properly. Now I've added GFCI outlets in the galley with no problems, but I'm still trying to figure out the one that's not working properly.

Here's the issue; If you push the test button on the outlet, it trips with no problem. But I also bought one of those outlet testers with the 3 lights on it. When I plug this into the outlet it indicates correct wiring, but when I press the test button it doesn't trip the outlet, instead it indicates hot and neutral are reversed.

I know hot and neutral aren't reversed, I've visually checked and double checked with a multi-meter. Also, at first I thought it was just a faulty GFCI plug so I went ahead and replaced it, but the new plug indicates the same thing.

I've read that if the GFCI outlet is ungrounded (2 wire vs 3 wire), then the tester may indicate something is miswired and fail to trip the outlet, even though things are working properly. However, this is a grounded outlet, and if I'm not mistaken, the ground is connected. With the multimeter, I'm measuring voltage between hot and ground; If the ground were not connected, I shouldn't measure any voltage between hot and ground, correct?

Does anyone have any suggestions as to why the tester won't trip the outlet?

This actually brings up a 2nd question. When I measure voltage between hot and neutral, I'm getting 120v (which is what it should be). However, if I measure voltage between hot and ground I get ~85volts, and I get ~35 volts between neutral and ground. I know I should have some voltage when measure across neutral and ground, but most of what I've read seems to indicate it should only be a few volts. Is 35 volts too much? If so, what could be the cause? As a note, this is the case for all the outlets on the boat, not just the GFCI I'm trying to figure out.

Thanks for any help
You should have no voltage between neutral and ground and you should have the same voltage between hot and ground as you have between hot and neutral.

Not being there at your boat I can only guess and my guess is that your ground connection has a problem. You should probably start by checking everything at the dock pedestal. Make sure that is correct before tearing your boat apart. Next, substitute a "known good" shorepower cable.
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Old 16-01-2016, 12:19   #3
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Re: GFCI plug question

Agree that there's a problem with the ground, and possibly the neutral.

Neutral and safety ground also need to be isolated from each other. Apparently, before GFCIs, it was common practice to tie them together on boats. This would trip the GFCI if there was one at the dock connection.

Finally, one thought on GFCI's inside the boat: I mistakenly bought ones with tiny green pilot lights in them, which indicate they're working. Great, but when away from shore power they'd pull enough juice to keep the inverter running 24x7, even when all other 120VAC loads were off.
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Old 16-01-2016, 13:38   #4
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Re: GFCI plug question

Is this the only outlet with 35V neural-ground? If all outlets are like this your shore power is likely messed up. If only one outlet then the boat wiring is loose, corroded or some other malady has struck somewhere.

Start by testing the source of AC power and work from there to the outlet with problems. Whenever neutral is more than a few volts there is something wrong somewhere.
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Old 16-01-2016, 14:04   #5
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Re: GFCI plug question

I'm down at our boat now re measuring things.

We have 5 outlets, 3 of them are Turned on with one breaker, and the 2 others are on another breaker.

The 2 together are both reading 120v hot to neutral; 112v hot to ground, and 18v neutral to ground.

Of the 3 together; 2 are reading 120v hot to neutral; 85v hot to ground and 35v neutral to ground. The 3rd is measuring like it's supposed to (120v hot to ground and 0v neutral to ground).

I'm sure the problem is with the boat, but I'll double check the dock pedestal just to be sure. From here I'm going to start tracing out the neutral and ground wires to see where they connect. Hopefully they're not all connected to the same bus somewhere.

Thanks for the responses so far, let me know if you guys/gals have any other thoughts.
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Old 16-01-2016, 14:26   #6
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Re: GFCI plug question

We had a similar problem.
Turns out that we had multiple GFCI on the same Circuit. Had an electrician check it out, and he rewired with standard outlets downstream of the first GFCI on each Circuit. As long as the wiring it correctly installed, the other outlets will work from the GFCI.
I thought he might be feeding me a line, so I checked the wiring at the house and lo and behold all circuits that require GFCI only have one and it feeds power to the other outlets on that circuit.
What I still don't understand is why the manufacture of the boat would install GFCI at virtually every outlet? I get it if only one outlet is on a circuit but not multiple.
Anyway, hope that helps.
And if an Electrician can explain why the manufacture would install multiple GFCI on a circuit, I'd appreciate it. Maybe it's a AYBC thing.
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Old 16-01-2016, 14:47   #7
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Re: GFCI plug question

Hey Blinker,

In addition to the good troubleshooting advice you have already received, be sure to test your new GFCI devices with your inverter and/or generator if you have either...

I have run into incompatibilities in times past- especially with modified-sine wave inverters...

And, as has been already suggested, I suspect you have a ground issue on the one errant outlet or series wired GFCI outlets...

Lastly, if you have either a galvanic isolator or isolation transformer, be sure to troubleshoot all the way to their connections.

In case this is helpful.

Cheers!

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Old 17-01-2016, 09:34   #8
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Re: GFCI plug question

Thanks for all the suggestions everyone.

I'm still digging through everything at the moment, I spent a good portion of yesterday wiring in a reverse polarity light, so I didn't get to trace too many wires.

Someone else mentioned the compatibility issue with gfci plugs and inverters the other day, I'll definitely have to check that one out.

I knew a single GFCI plug could protect non-GFCI plugs down stream of it, but only if they're wired in series. As far as I can tell, while some plugs are on the same breaker as others, they don't appear to be wired in series. All of the plugs only have a single 3 strand wire attached to them. My thinking is that they must all go to a common buss somewhere, but I haven't had a chance to dig that far into it just yet.. That might be today's task.

I'll let everyone know if I figure something out.

Thanks again.
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Old 17-01-2016, 09:58   #9
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Re: GFCI plug question

If you are a US boat and the inverter is installed power ABYC specifications the GFCI plugs will work same as if on shore power. Most of the "truck stop" and many other non-marine inverters cannot be installed per ABYC specifications.
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Old 17-01-2016, 10:06   #10
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Re: GFCI plug question

Just remember, the GFI has to come first if in series. Also remember that auto/ boat is reverse of residential. On a house panel, Black is hot, where is on a car black is ground. I once put an addition on a house and couldn't understand why I was getting shocked all the time. The owner of the house was an auto shop owner and wired the new panel himself. I finally checked the panel to see what the hell was up. He put all the blacks on the grounding side and made all the white legs hot. I almost **** myself. Sounds like a ground problem to me, but make sure there isn't anything else connected to that hot leg before it hits the gfi. I've seen a wire jumped buried in a bulkhead when chasing down the same problem your having. Previous owner spliced and taped in in a place you would never think to look.
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Old 17-01-2016, 10:11   #11
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Re: GFCI plug question

Oh, just before I get attacked, yeah I understand , boat, brown, blue, brown with yellow stripe. etc. Just saying, some blockhead could of reversed something somewhere.
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Old 18-01-2016, 18:37   #12
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Re: GFCI plug question

Just wanted to let everyone know we finally got the issues figured out. It ended up being grounding issues for all the outlets. For 2 of them, one of the ground wires just came loose, so all we had to do was tighten that up (these were the 2 outlets that were reading 112v hot to ground). For the other 2 (reading 85v), it took a little more work to find the problem. We ended up having to disassemble a lot of the trim work so we could trace out the wires, but eventually managed to find a factory installed buss behind a panel hidden behind one of the holding tanks.

I took a picture of what we found and I'll try to explain as best I can.



The first 6 wire groups (wire group = 1 set of hot/neutral/ground) starting from the bottom of the stack on the left of the photo are all AC wires, and this is where the problem was. The 2nd wire group from the bottom is the supply wire from the breaker panel to the large buss along the bottom (you can see the hot (red) and neutral (black) go through a small 2x2 buss first). If you look closely, you can see the ground for this wire is connected with the grounds from the wire above it and below it. However, the hot and neutral wires from the supply wire go to the right side of the buss and power the 5th and 6th wire groups from the bottom. The grounds for those wires are all connected together and run back to the buss. The problem was there was no wire connecting this group of ground wires to the ground wire from the supply wire. You can see the piece of wire I added along the bottom of the buss to connect the 2 groups of grounds together.

2 of these 3 wire groups go to the outlets I was having trouble with, so you can see the outlets weren't grounded at all. After adding the connector wire, the voltages on the 2 plugs are measuring like they're supposed to and the GFCI trips like it should when using the test plug.

I hope that makes sense, it's a little hard to explain without being able to point to the wires I'm talking about.
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Old 18-01-2016, 19:11   #13
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Re: GFCI plug question

You did good. One thing I've learned since buying Gray Hawk is that there are an incredible number of monumentally stupid people masquerading as marine electricians. There's plenty of dirt based electrical idiots but I think the proportions are substantially worse on the water which is scary. The only way to be sure is to understand the wiring yourself. From there if you feel the need to hire someone at least you can accurately assess whether or not you are dealing with a moron, which you may very well be more often than you would like to think. Your memory may be better than mine - its hard to imagine one that is worse - but I find it useful to draw detailed electrical schematics which I keep updating as I make changes or add components. Then before I start into an episode of troubleshooting or making improvements I can review the drawings to refresh my memory.
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Old 18-01-2016, 19:51   #14
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Re: GFCI plug question

Looking at those blocks in the pic you put up, you may want to move those frayed copper grounds closer to the neutral legs and away from the hots. Only need one loose strand to possibly arch over. Just saying
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Old 20-01-2016, 15:17   #15
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Re: GFCI plug question

Quote:
Originally Posted by CrustyChief View Post
We had a similar problem.
Turns out that we had multiple GFCI on the same Circuit. Had an electrician check it out, and he rewired with standard outlets downstream of the first GFCI on each Circuit. As long as the wiring it correctly installed, the other outlets will work from the GFCI.
I thought he might be feeding me a line, so I checked the wiring at the house and lo and behold all circuits that require GFCI only have one and it feeds power to the other outlets on that circuit.
What I still don't understand is why the manufacture of the boat would install GFCI at virtually every outlet? I get it if only one outlet is on a circuit but not multiple.
Anyway, hope that helps.
And if an Electrician can explain why the manufacture would install multiple GFCI on a circuit, I'd appreciate it. Maybe it's a AYBC thing.
The main reason a manufacturer would wire multiple gfci receptacles on the "SAME" circuit would be, the convienence of only the tripped outlet losing power, while maintaining power at all others on the cct.
All the gfci receptacles being fed from the same circuit would be tied into the line side only on each gfci receptacle not line in - load out as you would if you wanted the first gfci to protect all others down the line, the others in this case could be just regular receptacles, when the gfci trips you have protection for all but then will lose power on all that are wired this way on same cct.
A matter of convienence to have all separate, then also easy to identify the individual one that has tripped.
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