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Old 02-27-2009, 09:36 AM   #16
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GFCI feeing subpanel question


Inphase

It shouldn't but I think he is saying that it does not matter what breaker he energizes. But your absolutely right the branch breaker should trip out on overcurrent before the gfci. My thoughts are that he has a hot to ground fault...odd though it is happening on both sub panel branch breakers....it was certainly incorrect to say overcurrent at the gfci, my mistake. My thought was that he actually has amps flowing to ground not milliamps but not enough to trip the branch breaker. I have not commonly seen hot to ground faults that are milli amps in nature.

Edit: I just saw where you said possibly a ground being used as neutral. I would agree but he is saying the gfci is tripping with no loads turned on at the sub-panel so it has to be a phase fault of some kind if this is true...... but
back in the thread Scott says if he has all the grounds and all the neutrals connected to the neutral bar everything works correctly. That could only happen (if current is on a ground) if he left the feeder ground connected to the ground bar and he had proper separation of neutral and ground at the sub-panel. This also would throw out the window any hot wire to ground faults.

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Old 02-27-2009, 06:12 PM   #17
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Just got back home. I checked the outside disconnect and they had the neutrals grounded so I ungrounded them and wirenutted them together. In the box I also seen that each hot was connected red to red and black to black at each top lug which was labeled line in. Shouldn't the hots going out to the garage be on the bottom lugs? With them not being on the bottom lugs I can't see the fuses protecing anything. Well I left the hots as they were and was hoping fixing the neutrals would fix the problem. NOPE. Still trip the gfci.
Onto the sub panel: with the 2 circuit breakers off in the sub the main gfci does not trip but if I turn either one of the sub breakers on the gfci trips. I removed the wires from the ground, neutral, and breakers in the sub to ohm the 2 sets of wires, on the receptacle side there is no continuity between any of the 3 wires but on the light circuit i did have continuity between the hot and the neutral. That circuit is now wired as a "middle of the run" so no wires were needed to be coded hot, just simple black to black white to white. However it was wired as an "end of the run" circuit only needing one 12/2 going to it. But as far as upstream from the switch to the lights I don't think any wiring needed to be changed being its still black to black and white to white. But what would have caused the continuity between the hot and neutral on that circuit when I tested it at the sub panel? I went ahead and disconnected the neutrals (wire nutted) and hots at the switch and rechecked and there was no continuity so I left the breakers on in the sub panel and switched on the gfci and it still tripped.
I did make absolutely sure that all the grounds in the sub are connected to the ground bar and all the neutrals to the neutral bar and the neutral bar is isolated from and ground or metal. It is a Siemens 125 amp main lu box model # e0408ml1125su. Let me ad this now that I thought about it. Before adding the new subpanel, the old sub panel was also a siemens and it had just one 30 amp breaker (which should have been a 20amp) and the receptacles were wired to it and on the light circuit they had just run the black hot wire to the second main lug and snugged it up against the red 110v wire and lug. And of course all the grounds and neutrals were tied in together at the neutral bar. While I was at work, I had dad take all 3 neutrals (feed, receptacle, and lights) and wire nut them together and it worked! So with adding the brandnew sub panel my dad decided to change the "end of the run lighting circuit" to a "middle of the run" and now today i took all the 3 neutrals off and wirenutted them and still tripping gfci. You would think it had something to do with the lighting circuit but I totally disconnected that circuit and gfci still trips. HMMMMMMMM I know we're gonna figure this out. I wonder if I should just take the gfci out and replace it with a regular 50 amp double pole breaker? Is the wire length of about 150 ft out to the garage just too much for this gfci to operate correctly? The OLD sub panel had the grounds and neutrals together but isolated from the box and had NO grounding rod. Now without the ground rod the neutrals could be wirenutted together and the circuits worked. And now in my new sub panel i added the grounding rod with 6 ga coming up and terminating at the grounding block. Is the grounding rod causing a problem? Also does it matter on the hot black and red wires which one hooks to the main lugs A and B?
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Old 02-27-2009, 06:29 PM   #18
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GFCI feeing subpanel question


Put the neutrals back and take the grounds off the bar and make sure they are not touching each other or the panel metal. See if the breaker holds and the lights and power works. If everything holds, then turn the circuits off and re-attach each ground one at a time, re-energizing the circuits each time. If you get to one where it trips out, then you at least have a direction to start looking in.
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Old 02-27-2009, 06:42 PM   #19
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Cool, I gotta go eat and i'll be back in an hour or so and try that with the grounds.
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Old 02-27-2009, 06:58 PM   #20
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Forget about all this other stuff if the panel is wired correctly the ground rod with proper neutral and ground separation will not trip the gfci.

Do exactly what Inphase is asking. Only thing I would add is once you get the two grounds disconnected reenergize each branch circuit one at a time and see if the gfci trips with the grounds disconnected. If it holds then connect a ground one at at a time as Inphase is asking.
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Old 02-27-2009, 09:43 PM   #21
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ok, i disconnected the 2 grounds, 1 from each circuit. I left the 2 sub panel breakers on and went inside and flipped the gfci and it still tripped. Went back out and reconnected the 2 grounds and turned the 2 breakers to "off" and then turned the gfci on and the gfci tripped again. So now its tripping all the time now that i disconnected the neutrals from the grounds in the disconnect box.
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Old 02-27-2009, 09:49 PM   #22
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The gfci installed in my main is a Siemens 50 amp and I did read that there was a recall on this same one but only if it was made before 1998. I called into Siemens with the numbers on the breaker and they said it didn't apply to mine. Any chance I have a bad gfci. If grounds are hooked to neutrals in the sub panel does it make the gfci less sensitive so to speak?
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Old 02-27-2009, 10:00 PM   #23
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The gfci installed in my main is a Siemens 50 amp and I did read that there was a recall on this same one but only if it was made before 1998. I called into Siemens with the numbers on the breaker and they said it didn't apply to mine. Any chance I have a bad gfci. If grounds are hooked to neutrals in the sub panel does it make the gfci less sensitive so to speak?
I doubt it's bad. Your basically bypassing it's function by bonding the neutrals and grounds. Don't do that. Leave it a 4 wire feed and put in a normal breaker if your not able to find and fix the problem.

Did you get a chance to take photos of your setup?

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Old 02-27-2009, 10:11 PM   #24
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i will take a photo of it tomorrow and post it. Does it make sense that it trips now all the time after disconnecting the neutrals from ground at the disconnect box?

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Old 02-27-2009, 10:59 PM   #25
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Scott

This whole thing with the gfci tripping keeps changing. I do not think the gfci is bad. I think at this point you need to eliminate any possibility of an overcurrent fault causing this problem.


A safe method would be to do continuity checks with the wires disconnected at the gfci and disconnect and then continuity from the disconnect to the sub-panel. There should not be continuity between any two wires.

You can also replace the gfci with a regular double pole and make sure the 2 branch breakers at the sub are off then energize the breaker. I do not recommend doing this as there is a risk of arc flash. If you have an overcurrent issue it is possible that you have destroyed the gfci as many times as you have open and closed it.

Go ahead and post pictures if you want.
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Old 02-27-2009, 11:09 PM   #26
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Scott

This whole thing with the gfci tripping keeps changing. I do not think the gfci is bad. I think at this point you need to eliminate any possibility of an overcurrent fault causing this problem. Remove the gfci and replace it with a regular double pole breaker. Leave the branch breakers off in the sub-panel and energize the double pole. If it trips you have a overcurrent fault on the feeder somewhere either in the conduit or at the disconnect or sub-panel.

A safer method would be to do continuity checks with the wires disconnected at the gfci and disconnect and then continuity from the disconnect to the sub-panel. There should not be continuity between any two wires.
Go ahead and post pictures if you want.

He did mention that the wire is Not in conduit and is direct burry. Hopefully it is uf-b. He also expressed concerns earlier about it not being deep enough or tree root damage. Some of his posts were long, just thought it would be helpful to point out these things.
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Old 02-27-2009, 11:19 PM   #27
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GFCI feeing subpanel question


Jamie


Yes his posts are long and we are really getting nowhere as the events keep changing. However it is now looking like a fault with the feeder and not a neutral to ground bond issue.
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Old 02-28-2009, 06:28 AM   #28
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GFCI feeing subpanel question


Did you remove the neutral to ground bonding screw in the subpanel downstream of the GFCI?
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Old 02-28-2009, 07:31 AM   #29
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With the gfci tripping lastnight even with the breakers off in the sub panel really puzzled me because it didn't do that before. But I will disconnect everything and check for shorts in all the wires. I did just check the wiring that is buried and it is 6/3 but rated for indoors not the nm-b. This was like this when I bought the house. Even though the indoor rated wire is shielded with a thin plastic-like housing will it not be waterproof enough?
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Old 02-28-2009, 08:40 AM   #30
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Scott

If the wire isn't direct bury rated you might as well stop. There is no sense in going on with your problem. I thought it was just buried shallow.

You must replace the cable with a direct bury cable like UF-b or wires in conduit like thwn. NO choice in the matter.

BTW nm-b is rated for indoors/dry only. You can do the tests if you want but it really is pointless with the wrong wire in the ground.

UF-b looks like this and is gray in color usually.....
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GFCI feeing subpanel question-uf-b.jpg  

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