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I've been doing some remodeling on my house and had the need to move some electrical outlets. While doing so, I noticed that the ground wire wasn't hooked up on any of the outlets in the circuit (through a bathroom, no less). It was three wire cable, so the ground wire was there. It was just bent back or snipped off at each box and not connected to the outgoing ground line in any way.

If it were 2-wire cable, I could chalk it up to someone being cheap, but I can't imagine someone being so lazy that they didn't connect the ground wires when they were right there and available. Most of the other circuits in the house seem correct, so maybe this is intentional?

Does anyone know a legitimate reason you would wire up a circuit and not connect the ground wires?

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What type of cable? Armored or NM (non-metallic)? I am assuming you are talking about NM but want to confirm. –  Jeff Widmer Sep 13 '10 at 14:49
    
Definitely NM, I think it was NM 14-3 (but it could have been NM 12-3). –  JohnFx Sep 13 '10 at 20:43
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Oh, and I should add that the house was built (and likely wired) by the homeowner I bought it from. He was a mechanic (not a contractor by trade), and I've seen some other horrors he built into the place, so it is not beyond reasoning that he simply was ignorant of how things work. However, he did it right in the other rooms, that made me hesitant to dismiss it to incompetence right away. –  JohnFx Sep 13 '10 at 20:45
    
I wouldn't trust any wiring that a previous home-owner wired themselves, even if it was an electrician. There is to much demand to do it quickly, so that you can run the vacuum cleaner, for example. –  Brad Gilbert Sep 15 '10 at 15:05
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@Brad Gilbert isn't there also alot of demand to get it right; so the person doesn't end up responsible for electrocuting a family member or setting fire to their or their neighbour's house? I've seen some bad wiring done by amateurs. But I have also seen some really terrible stuff done by professionals (presumably under time pressure from their bosses). I have come across so many unexpected things, that I have got the point where I don't really trust any of it. –  flamingpenguin Nov 23 '10 at 18:22
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7 Answers

up vote 19 down vote accepted

No, there is no reason not to have the ground connected. Even with armored (BX) cable, you should connect the ground. There is an older style of armored cable that uses a wide metallic strip (inside) as the ground which is a bit flaky since it's hard to get a good connection (it is just supposed to connect with the box connector). The actual armor though is not designed for grounding, and should not be used or relied on as a ground (though in most cases, the electrical connection exists for it to work as ground).

Let me be clear though -- you should check what is on the other side of the wire, and make sure it actually is grounded (or, possibly, not connected -- which you can fix), and that it is not being used for some other purpose. Just a red flag for me: when someone snips off the ground it means they didn't know what they were doing, so don't assume that anything is correct.

One thing to look for - there should only be one common ground in your house, and everything should be tied together. If you have, for example, two separate ground rods and circuits mixed, you can have ground loops and noise issues, especially if you have sensitive electronics (TVs, amplifiers, computers) connected. All grounds should be connected together at or near the main panel.

On the same topic, you should have a ground wire connecting your electrical grounding wire to all copper pipes in your house, and to any gas lines. Be careful with placement, as often you need a jumper wire to go around a non-conductive water meter to connect both sets of pipes together.

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You can have multiple ground points, provided that they are connected directly to one another through a large wire. For example, connecting the Neutral coming in, with a connection with your water pipe, along with a ground rod, all connected at or near your main panel. –  Brad Gilbert Sep 15 '10 at 14:57
    
@Brad: Thanks, wasn't sure if you could have more than one. Updated post –  gregmac Sep 15 '10 at 15:20
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Note that even if your house was plumbed with nothing but Pex, that the pipe coming into your house, is likely metal. I would connect the ground that goes to your main panel as close to where the pipe comes in as possible. –  Brad Gilbert Sep 15 '10 at 15:40
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National Electrical Code 2014

Article 406 - Receptacles, Cord Connectors, and Attachment Plugs (Caps)

406.4(D)(2) Non–Grounding-Type Receptacles.

(b) A non–grounding-type receptacle(s) shall be permitted to be replaced with a ground-fault circuit interrupter-type of receptacle(s). These receptacles shall be marked “No Equipment Ground.” An equipment grounding conductor shall not be connected from the ground-fault circuit interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter receptacle.

(c) A non–grounding-type receptacle(s) shall be permitted to be replaced with a grounding-type receptacle(s) where supplied through a ground-fault circuit interrupter. Grounding-type receptacles supplied through the ground-fault circuit interrupter shall be marked “GFCI Protected” and “No Equipment Ground.” An equipment grounding conductor shall not be connected between the grounding-type receptacles.

In both sections it says not to connect the grounding conductor.

An equipment grounding conductor shall not be connected from the ground-fault circuit interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter receptacle.

An equipment grounding conductor shall not be connected between the grounding-type receptacles.

The basic idea here is that if there isn't a solid grounding path back to the panel, the grounding conductor should not be connected. If I came across a situation where the grounding conductor was not connected, I would assume there isn't an adequate grounding path.

See this answer for more information on replacing 2-prong receptacles.

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The only legitimate reason I can think of: if the Romex extended an ungrounded circuit elsewhere.

Now, that's a bad idea for a bathroom (except perhaps for the light circuit). And if you ever do this, please label the cable to explain the situation. Or, better yet (as I have done) salvage some actual two conductor wire for the run.

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I've seen this before in my own house. A previous occupant upgraded the wiring in one bedroom from knob-and-tube to romex. But the romex was connected upstream to a knob-and-tube circuit. Knob-and-tube circuits have no ground wire.

Whoever did the wiring didn't connect the ground wires because they wouldn't have done anything because they weren't connected upstream.

I'm not sure whether this was due to laziness or as a friendly signal to anyone who worked on the wiring in the future that it wasn't grounded.

Regardless of the reason, I'm assuming it was a code violation, both in my case and yours.

So to answer your question, in your bathroom there's not a good reason why the ground wire should have been disconnected.

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+1 on this. Fake grounds are worse than no ground. –  Bryce Jan 8 at 0:52
    
Yes +1. The question asks for if there is any valid reason. Everyone else is just saying that you should always connect ground. Not having a ground and using a GFCI would seem to be a valid reason to clip the ground wire -- to make it clear that wire is not actually grounded. –  ThePopMachine Jan 8 at 15:10
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The only time I've ever heard of intentionally lifting the ground is in the case mixing panels and the associated equipment (equalizers, compressors) for live bands. Sometimes there's noise which can be resolved by lifting the ground. So, unless you are having live bands performing in your bedroom, I'd advise against it. (Also, we never pulled the ground at the source, but at the individual piece of equipment.)

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In installations with dodgy grounds, isolating the ground to sensitive equipment is a short term solution, only so the show can go on. Still, even in that situation, all the connected equipment should be grounded together to perform well. Once the special event is complete, there should be concentrated effort to find out why the original ground is noisy, D.C. biased, or whatever the problem actually is and fix it. In a steel mill computer room, I once measured 75 volts between the grounds at opposite sides of the room. The electrician said he didn't know what to do with computer equipment. –  wallyk Jan 8 at 8:48
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Remember that ground can save lives.

I do not live in the US, but in my country the rules for ground are very strict. If you can connect the ground you have to do. And you are not allowed to have grounded and ungrounded equipment in the same room.

But reality often differs...

I have jusd replaced and expanded the electricity in our house. In the shed anything was grounded but the ground wire was not attached. So I did attach the wire. Some days later (during the housewarming party) we saw a flash and heard a loud bang. After some investigation I found out that there was an loose (life) wire that connected with the metal (now grounded) case which resulted in a nice and spectacular short circuit.

This means, that If I hadn't connected the ground, the metal case of the light was connected to 230 V AC unnoticed. Anybody could have touched that with probably fatal results. So I'm really glad I have the habit to examine and correct all electrical connections.

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I'm not disputing the value of grounding electrical circuits. I'm just asking whether there is some valid reason that someone might have neglected to do so when it would have been just as easy TO do it. The way this is wired it seems like an intentional decision not to do it. –  JohnFx Sep 17 '10 at 16:14
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Two possibilities come to mind:

  1. The original contractor was negligent: the circuit is not grounded. This might either be because he was a criminal schmuck, or because he thought that GFI was somehow a substitute for grounding (which would explain why it's only in the bathrooms).

  2. You are using armored BX cable, the metal sheath of the BX cable is grounded, and it is electrically connected to the outlet box which is electrically connected to the ground lead so the outlet is really grounded

I once came across a bunch of boxes like this (#2) in an old Manhattan brownstone. I couldn't find any ground leads at all, but when I plugged in an outlet tester, it did appear to be grounded, which surprised me. Then I realized the box itself was grounded via the sheath of the BX cable (which is exactly as it should be, to protect for the case of a loose connection inside the box) and that the receptacle itself will be grounded if the box is grounded. In fact even if you have a ground lead, it's good practice to connect it to the metal box with a pigtail.

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It wasn't a contractor, it was a do-it yourselfer who built it from a log home kit (likely the problem right there). Also it isn't armored cable, just NM 12/2. See my comments on the original post for more details on that. Still +1 for some good suggestions that might help others. –  JohnFx Sep 13 '10 at 20:48
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When I wire up metal boxes, I always have a pigtail going to the box, along with a wire going to each outlet or switch, in the box. It's possible to have a partial ground, where if you press the GFCI tester button on an outlet tester, and have all three lights come on. –  Brad Gilbert Sep 15 '10 at 15:01
    
It's not only good practice: metal boxes must be grounded! –  Jeremy W. Sherman Jul 24 '12 at 21:41
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Joel, older BX cable like you described is not safe for equipment grounding. The ridges in the cable cause considerable impedance, meaning that though your outlet tester will read 120V between the hot and ground (and mistakenly tell you it's wired correctly), if a ground-fault were to actually occur the impedance could cause the breaker to not trip, leaving the device hot and ready to shock you the next time you touch it. This is not an issue with newer BX cables because they have a bonding strip (basically a separate grounding wire). –  BlueRaja - Danny Pflughoeft Sep 9 '13 at 20:21
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