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I moved into a new house and was working on making a three way switch work properly when I came across some creative wiring. The traveling wire between the switches was only two wires, and the ground from it had been electric taped over and used as a neutral wire for the lightbulb.

Obviously normally this would be very dangerous because you wouldn't have ground wire in case of short circuit, however, there is an outlet by one switch and another switch by the other. The grounds from the wires for those has been used as the ground for the switch. That outlet and light are on the same breaker. Here's a rough diagram of how things are wired:

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What are the risks as a setup like this? As far as I can tell, everything is grounded and should be okay but I'm no electrician.

Edit: I was using the word "drain" instead of "neutral" and fixed it.

yesennes
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  • the ground from it had been electric taped over does this mean that it was a bare, copper (no insulation from the factory) wire covered at each end in electrical tape, or does it mean that it's got some other factory insulation color and has had some green tape applied to "make" it a ground? used as a drain wire what does that mean? Unless there's water in the box that the bulb is mounted to, I'm not sure what would be "draining". – FreeMan Oct 18 '21 at 17:58
  • Ground wire never are to used except for ground. By "drain" you mean to say neutral? – crip659 Oct 18 '21 at 17:59
  • @crip659 Drain wire is the term for a ground in metallic-sheathed signal cabling/wiring to reduce signal noise, etc. OP's use of it here is a misnomer; they mean ground, probably, since both ground and drain wires are always bare. There's no need for a drain wire in non-signal wiring, like the kind that provides power throughout the house. – TylerH Oct 18 '21 at 18:23
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    @TylerH Nice to know, thanks for info. – crip659 Oct 18 '21 at 18:32
  • Sorry, I don't really know the proper terms. By drain I mean the one of the wires that is normally part of the circuit from the bulb. I think neutral is correct for that. By ground wire I mean its the wire that's bare under the first level of insulation. – yesennes Oct 18 '21 at 18:41
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    Can you post photos of the insides of the boxes involved please? – ThreePhaseEel Oct 19 '21 at 02:00
  • Why are you trusting your life and house and family to a bunch of internet strangers, rather than hiring someone qualified? – Robbie Goodwin Oct 24 '21 at 19:13

3 Answers3

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What could possibly go wrong?

  • If the ground wire is bare copper, you massively increased the risk of a ground fault, which can kill somebody or burn the house down.
  • If the ground wire has a smaller cross-section, it will not be protected by the breaker from overheating and can burn the house down.
  • Somebody working on the system may falsely believe the ground wire is, in fact, ground. Neutral wires are just as dangerous as live wires (e.g., a loose neutral may unexpectedly become hot if any appliance on the circuit is switched on). This can kill somebody.
  • Somebody may 'fix' the ground by tying it to ground, creating a electrocution hazard long after the 'fix' has been made. This can kill somebody.

In my attic, I found a junction box where the owner had made sure their setup was 'safe': they connected an insulated 2.5mm² wire to another insulated 2.5mm² wire. Only, one was brown and one was green/yellow. Perhaps they decided to 'safely' ground an unused live wire? Or used a bit of leftover brown wire to ground the ceiling lamp? If I hadn't found this box and instead repurposed the other end of either cable, I may have killed somebody (or myself) or burnt the house down. I'm sure the previous owner did not realize that.

Sanchises
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You have ground being used as neutral. That is a serious code violation and can cause a number of dangerous problems.

In the old days, the only real solution would be to run a new cable. Fortunately, today we have smart switches to the rescue! Look for a smart switch that has 3-way operation but that only needs one traveler between the switches. That can be by using some sort of signaling over the power line or by one the switches being a wireless remote.

Make sure to get something that is properly UL or ETL listed - generally that means either knowing exactly what you want (specific manufacturer/model) or by shopping at a traditional bricks and mortar store such as Home Depot or Lowes (shopping online is OK, as long as the items are sold in the US stores they will be properly certified) and not an exclusively online retailer where the items may be provided by a 3rd-party and of dubious quality and safety.

manassehkatz-Moving 2 Codidact
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  • What are the dangerous problems? Maybe I'm being overly simplistic, but a wire's a wire, and its the same gauge as the others. The normal function of the ground wire is being done by the other wires I mentioned. – yesennes Oct 18 '21 at 18:45
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    The electrical is designed so that under normal circumstances, ground does not carry any current at all and neutral carries as much current as hot! This, combined with ground and neutral only being connected at one location (main panel), makes it so that metal parts (cases of major appliances, electrical boxes/conduit, etc.) function such that if a hot wire comes loose (or certain other problems) there is a short circuit and very quick breaker trip, but the rest of the time those metal things are totally safe - if ground and neutral are combined, those metal parts are not safe. – manassehkatz-Moving 2 Codidact Oct 18 '21 at 20:13
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    In addition, while not directly relevant for your light circuit, in general because ground only carries current in emergencies, the ground wire is often (with larger circuits) a smaller wire that would not be able to handle the full circuit current for an extended period of time, saving money on wire while still providing a path for current for a short time when needed. Plus if the ground wire is bare (it can also be green or green/yellow) then even if it is treated as neutral in all its deliberate connections (switch, light fixture) it would contact other stuff (because it is bare). – manassehkatz-Moving 2 Codidact Oct 18 '21 at 20:17
  • I think since mine set up only use a ground wire to connect two different neutral source and not actually going to ground, I should be safe on the first. I suppose it being a bare wire means it has one less layer of insulation around it would could be dangerous if it breaks, or if the electrical tape around it in the boxes wears down. – yesennes Oct 18 '21 at 21:21
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    The problem is that one person can take one shortcut (using ground as neutral) and then another person takes another shortcut (perhaps wiring an MWBC incorrectly) and soon enough, the shortcuts kill somebody or burn the house down. – manassehkatz-Moving 2 Codidact Oct 18 '21 at 21:24
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    "A wire's a wire". Code isn't there to be annoying. It's there for safety. There are reasons, you're just a novice and don't know them. So stop thinking you can outsmart the experts when a perfectly viable solution is on the table. – Harper - Reinstate Monica Oct 18 '21 at 23:42
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    @Harper-ReinstateMonica If you couldn't tell from the fact I'm asking a question on forum, I know I'm a novice and don't understand the reasons. I hope you will forgive me for not taking code's word blindly but inquire as to the reasons it exists. I've got a long list of things wrong with my house, and I'm trying to prioritize the most important things to fix first. – yesennes Oct 19 '21 at 15:02
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    OK, apologies. The problem is, we insulate neutral for a reason. It is perfectly common to have 120V on the neutral wire, the most trivial wire failure can cause it, even maintenance can, or removal of a device. The conductors in NM have THHN insulation on them, the ground does not. – Harper - Reinstate Monica Oct 19 '21 at 17:35
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    I wonder if there would be any technological or safety problems with designing a smart switch to use a ground connection instead of neutral, but do so in a way that would be guaranteed never to leak more than 250uA through it? If one had too many such switches downstream of a GFCI they could cause false tripping, but at 250uA each one would need a dozen or so for that to be a problem. – supercat Oct 20 '21 at 17:46
  • @supercat That actually is a real thing. See my many answers about "Power for smart switch/motion detector/timer/etc. needs to come from: neutral, battery, leakage through hot or ground". – manassehkatz-Moving 2 Codidact Oct 20 '21 at 17:54
  • This would also cause issues with a GFCI/AFCI breaker, right? – JimmyJames Oct 20 '21 at 18:32
  • @JimmyJames Correct. The issue ("normal" current through ground > GFCI threshhold) is the same whether it is a GFCI breaker or GFCI receptacle. With the one advantage that with a GFCI breaker, it is always the entire circuit on one GFCI. With a GFCI receptacle it can be split, which can help alleviate the problem. – manassehkatz-Moving 2 Codidact Oct 20 '21 at 18:36
  • @manassehkatz-Moving2Codidact: Are there any standards as to how much current such devices are allowed to pass through the ground lead either in normal operation or in worst-plausible-case malfunction? Could device be approved for use in both repair/retrofit applications where neutral is unavailable and its standby current return wire would be grounded, and also in new installations provided that its standby current return wire is connected to a proper neutral? – supercat Oct 20 '21 at 18:44
  • @supercat I know I've seen some information on all of that, but don't have time to research it right now. But yes, there are specific rules/guidelines. – manassehkatz-Moving 2 Codidact Oct 20 '21 at 19:04
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I'm assuming by drain, you mean neutral. Ground wires can not be used as any other conductor, repurposed. If its green insulated or bare copper, then it must be used as a ground and only as a ground.

JACK
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