120V between Neutral and Ground

Mar 16, 2011 12 Replies

I have been trying to trace down where a circuit starts showing voltage between my ground wire and neutral wire. I found the a receptacle on the circuit that is correct where the neutral and ground show 0V, and then a box which I believe is the next receptacle that shows 120V between the ground and neutral. I have looked in both boxes and everything looks correct.


1st Box H->N = 120V H->G = 120V N->G = 0V


2nd Box H->N = 120V H->G = 0V N->G = 120V



What can cause the above scenario. A short? A broken wire? Also, is this dangerous? I think it has been like this for awhile.


Maybe the white and black wires have been reversed between the first and second receptacles.There maybe some other junction between these outlets. It's not an open or short. You have proper voltage at both receptacles

Also something else I just thought of. Downstream from the bad box, there is a light and the switch leg shows voltage between the neutral and the ground when the switch is off.

' If you have 120 between your neutral and ground, that's good. They don't bill you for current on either of those conductors, so if you reconnect your circuits, you can run your electric things for free.

It looks like somewhere the neutral and the hot wires have been reversed.

While you are probabaly not in danger of a meltdown, do not use the socket that has the faulty wiring.

I don't see how it could be anything but. Likely just switched the wires, the ground is correct.

Jeff

It's probably because they are using a black or red wire for the neutral. The neutral MUST be white. If any other color is used, that wire becomes Hot.

Also something else I just thought of. Downstream from the bad box, there is a light and the switch leg shows voltage between the neutral and the ground when the switch is off.

More evidence that the black and white wires got reversed. This switch is now breaking the neutral, and the hot is going directly to the fixture.

Who did the wiring in question? If licensed, their license should be rescinded.

I am just curious....,

If I had a situation like that (I don't), would one way to try to figure out where the wires got switched be to use a continuity checker?

In other words, turn off all of the power and then use a continuity checker with a long wire and alligator clip attached, and try to trace which wire from the first box has continuity to which wire in the second box, etc.

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I agree. Since you are just guessing this is the downleg box you really don't know. Power it all down, disconnect the wires and start checking continuity with an ohm meter or continuity checker. If it looks like a wire leaves the box as one color and shows up in the other box as another color that means there is a box between the two you have not found. Or a splice buried in the wall.

Wires are reversed, possibly at the outlet you're measuring at. Find the circuit's breaker and pull the outlet and make sure green or bare copper goes to green, black to gold and white to silver. Make sure any pigtailing is properly done. Find all other outlets on the circuit and check them as well. Get a 3 prong outlet tester with little neon lights to test each outlet for correct polarity and grounding ($5)

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If all the outlets pass but the lamp switch wiring is still screwy, then I would suspect something a little more difficult to track down. Is that switch a dimmer, timer or other powered switch? I often find people perplexed when installing these devices in a lamp fixture circuit that doesn't have a neutral wire so they pull one from somewhere else, often with very bad results.

-- Bobby G.

It's a little difficult. You have to disconnect the conductors from their line and any loads first. Otherwise you get backfeeds. The problem is that you don't have any good way of knowing that you've got everything disconnected. Branch circuit wiring generally goes, "as the crow flies", so you can usually find these problems by opening all related junction boxes in the vicinity of the problem

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