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I was replacing some outlets in my house with tamper-resistant ones, and came across one where the white and ground were wired together, as seen in this picture. Why? Is that okay or appropriate ever? It was clearly done on purpose.

When the house was inspected, the inspector detected significant current on the ground. Is it possible that this wiring is the reason?

enter image description here

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I've heard of people mistakenly bonding ground and neutral in a subpanel... but this is taking it too far! :-) –  Jay Bazuzi Jan 10 '12 at 4:02
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Seeing the mixed use of screw terminals and back stab tetminals, throws a red flag to me that somebody with little experience has messed with this wiring. –  Tester101 Jan 10 '12 at 11:52
    
Wow, that is scary as heck. Good catch. –  Alex Feinman Jan 10 '12 at 13:49
    
Under NEC, verboten. –  Fiasco Labs May 24 '13 at 1:11

4 Answers 4

Yikes, good find! This is most definitely the reason. The ground and neutral are only supposed to be tied together at the main panel. In this case, instead of only the neutral carrying current, both the ground and neutral will carry it.

There is no legit reason that I know of to do this at an outlet. I wonder if perhaps the neutral was open and the previous person was trying to cheat to make the outlet work? Do disconnect this. I would check other outlets in the house. An outlet tester may help speed this up but they don't detect all conditions.

Grounding is an important safety aspect of your house. If you suspect there is a more systemic problem with the houses grounding, get an electrician to take a look. Better safe than sorry.

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Those little testers are great, but I don't think they can detect this condition. Note that the testers don't detect neutral & ground reversed. Consider that neutral and ground are bonded at the main panel. –  Jay Bazuzi Jan 10 '12 at 4:01
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Be sure to check that both ground and neutral are okay. I would really want to find the other end of this wire to see how it's connected, as this looks very strange. I can't think of a reason to do this (considering there are no downstream circuits) aside from maybe a broken wire? If this is done this way, there are likely other strange/wrong things and so you should not make any assumptions about anything you're working on. –  gregmac Jan 10 '12 at 6:52
    
Greg is right, this may be a sign that the neutral is not good all the way back to the panel and the ground was used to complete the circuit. Or maybe the installer just made a mistake. Pull the neutral to ground wire and check for proper voltages. –  shirlock homes Jan 10 '12 at 10:47
    
Steven's answer is good advise. Check out other outlets for the same condition. –  shirlock homes Jan 10 '12 at 10:49
    
I've seen it done when the home was built without a ground line in the electrical system (1950's). It's not right, but it would pass the little plug-in tester. However, the ground wire going back into the wall makes me think this isn't the case and the others are on the right track with the broken ground or neutral suspicion. –  BMitch Jan 10 '12 at 11:36

It's called a bootlegged ground. This is commonly done in older houses that had a two prong receptacle and was updated to a three prong receptacle. The old house didn't have a ground and this tricks the inspector's electric checker, so your house passes inspection.

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No, the neutral and ground should never be wired together. This is wrong, and potentially dangerous.

When you plug in something in the outlet, the neutral will be live, as it closes the circuit. If the ground is wired to the neutral, the ground of the applicance will also be live. This can be felt as a tingling if you touch the grounded casing of the appliance, because most of the current still goes through the neutral where the lowest resistance is.

However, if there is something wrong and the neutral is disconnected, it will make the appliance dangerous. If you touch the casing, and some real ground (like a water pipe) at the same time, you will close the circuit and carry all of the current.

So, connecting the ground to neutral totally defeats the purpose of having a ground, and actually makes it more dangerous than not having the ground at all.

When the inspector was measuring the ground, he was actually measuring the neutral, which naturally shows a current when something is connected somewhere in the circuit.

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How do you square this "never" with Simon Richter's answer? (even though it's clearly wrong in this case because it's affecting the ground line for the house, rather than just the ground pin of the outlet) And "if there is something wrong and the neutral is disconnected" - well, what if, in a normal correct wiring situation, "there is something wrong" and both are disconnected? –  Random832 Jan 10 '12 at 14:22
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@Random832: If there is no proper ground line, you shouldn't use a grounded outlet in the first place. If the ground would get disconnected in a correct wiring, it's still not dangerous like connecting the ground to the neutral, because the casing of the appliance will just be connected to nothing. –  Guffa Jan 11 '12 at 10:47

That looks as if someone misunderstood something.

If there is no "proper" ground line, it is typical for the ground connector in the outlet to be wired to the neutral line. This gives a small voltage between the grounded metal parts of devices connected to it and true ground if phases are unbalanced, which is clearly suboptimal, but if you have a faulty device where a hot wire touches the case, that will at least blow the fuse.

It is however wrong to connect ground to neutral in the wall.

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Certainly the wire coming into that box has a ground line, but I can't say for certain what it's wired to wherever it goes... –  Scott Stafford Jan 10 '12 at 21:06
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If there is a ground line, there is never any reason to connect neutral and ground. –  Simon Richter Jan 11 '12 at 6:43

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