how to know if unknown wire is "neutral or ground"?


I'm trying to add an outlet from 2 wires that are just hanging out of the wall. I followed the wires to the attic and only one wire goes to the attic. The other wire went somewhere else.
I tested the wire and found out that it's either a ground or a neutral. How do I find out for sure if this is a "ground" or "neutral". If it's a neutral, then this outlet I'm trying to add is almost complete. If it's a ground then I'm in for another few hours of work.
Thanks, stan
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Stan wrote:

Stan,
It doesn't matter what those mystery wires are, and nothing has changed since you posted two weeks ago. Again:
"All conductors of the same circuit and, where used, the grounded conductor and all equipment-grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted"
If you google appropriate portions of the code quoted above you can learn more, including the rationale.
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What does that mean? Are you saying the ground and neutral are the same wire?
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Stan wrote:

No. Absolutely not.
I think you need to consider the possibility that you're in way over your head and need to call an electrician.
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On Wed, 26 Aug 2009 22:28:42 -0500, Mike Paulsen

I think we established that a while back in another thread. I only hope that Stan doesn't kill himself, someone else, or burn down his or someone else's house!
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If you're talking about the duplex problem and which side of the duplex the hot and unknown wire come from its relatively simple to determine regarding a ground wire and a neutral wire.
All neutrals should connect electrically to the actual grounding rod via a grounding connection inside the primary breaker box. This is a single wire connection from the neutral terminal where all the neutrals connect. This wire connects to the ground terminal bus. The ground terminal bus is physically directly connected to the grounding rod. via a unsheathed copper wire. With power removed, disconnect the wire connection from the neutral side to the grounding side. After this is done re-energize the power panel. Go check for the unknown wire for enabling power. If doesn't work now, its a neutral. If it does, its a grounding wire. Reverse the procedure to connect the neutral and grounding sides in the main breaker panel.
You have to check both main breaker panels this way for both sides of the duplex. If it is a neutral, it will also tell you which duplex main breaker panel it is originating from.
Simply denergizing either duplex breaker panel will tell which side the "hot" is coming from.
Will help with the grounding wire question once you established the answer to the neutral question.
--
Dave



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On Aug 26, 8:22pm, "Grasshopper" <NONE> wrote:

Dave, Thanks for you detailed answer. What I did was I disconnect all the neutral's from both of the fuse box. (Since I live in a duplex.) However, the problem is some of the electricity still works. I don't know where it's getting the neutral from. One unit all the electricity went dead. The other unit everything stayed on but 3 outlets and one light. Weird? Any other suggestions?
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It is possible that devices remaining connected complete the circuit between the two hots. The problem is that the load is likely unequal and that will cause higher voltage on one side and lower voltage on the other. Bad for some stuff.
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Stan wrote:

You need to disconnect the hot wires to kill the power, not the neutrals. Disconnecting all the neutrals is foolish and dangerous. CALL AN ELECTRICIAN YOU IDIOT!
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Stan wrote:

Join a club, shooting, chess, cooking or knitting etc, make friends with an electrician (or you could go to tech and learn the business)
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To find an electrician like others suggested, go to this site, then click on your city/state on the right side, then look for ads under "Services", or post an ad in "gigs".
http://www.craigslist.org
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Smartass had written this in response to http://www.thestuccocompany.com/construction/how-to-know-if-unknown-wire-is-neutral-or-ground-17936-.htm :
Stan wrote:

If you have 2 wires coming out of the wall and only one goes into the attic, that suggests that your looking at wires for a switch rather than an outlet. You may have an unswitched hot wire from the panel and a switched hot wire to an overhead light, for example. That being the case, the neutral is connected to the other side of the light socket.
The right thing to do is run a neutral wire from the panel to the new outlet. There is a possible Micky Mouse solution: Short out the light socket and the switched hot wire becomes neutral. Of course, that would be a serious code violation! But it would work.
By the way, just because you measure 120vac on a wire is no proof that it is hot. One time, I was installing a scale in the meat locker of a newly constructed Grocery store. I plugged my drill into an outlet, and when I pulled and released the drill trigger the refrigeration turned one and off.
------------------------------------- Retired tech.\\//.
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