neutral wire is hot, How to track down the problem area?

olympia_gardenerJuly 5, 2012

We bought a house years ago and now we try to put a ceiling light to the basement ceiling. There is a existing box on the basement ceiling ( i assume was put there by previouse owner). So theoratically, all we need to do is tight black wire to black wire , white wire to white wire together then the wiring job is done.

when we un-tight the wirenut in the box, to our surprise, one of the white wire is hot ( there are 4 white wire tighted together) even with the circuit break is off. I suspect this hot white wire has been mixed/switch into hot wires somewhere in the circuit , other circuit, floating, etc. possibilities. Would anyone recommend a best way to track down the location so I can fix this problem since the basement is finished , hard to look between/behind the walls.

Also, the cable looks like NM 14-3 , red , black, and white came into/out the box via conduit. Although, to my knowledge, there should be a 4th bare wire, but I did not see it anywhere, Could anyone here confirm if Romex NM only has red/black/white 3 wires in the cable? If this is the case, which color wire should serve as ground?

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Ron Natalie

If there 's 14/3 in the box chances are you have a multi wire branch circuit which means there are two poles (could be two different breakers, handle ties are not strictly required) feeding that circuit.

If that is the case, you've NOT turned off the circuit (fully).

If the circuit is fully turned off, and there is current present on the neutral something is seriously wrong. If the circuit is on (at least partially) voltage on the neutral usually means it is open somewhere and no longer grounded (which is sure to be the case if you disconnected that bundle of white wires in the box that were wire nutted together).

    Bookmark   July 5, 2012 at 5:41PM
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are you sure it not feed at the light..and not a 3way?

ground is bare or green..shouldn't anything else

14/3 would be used in a 3way many switches control the light..more than 1..its a 3way.only 1..might be hot at the light..


    Bookmark   July 5, 2012 at 5:50PM
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It's not a "real hot wire" with high current behind it. Just because you get a small spark with it when you touch it to the other neutrals or read 110vac on a meter between it and the others doesn't mean much.
You could try connecting a clamp on ammeter around a short length of wire completing the circuit to give an idea of what amount of current is involved. That should give a good clue to the mystery item.

    Bookmark   July 5, 2012 at 8:13PM
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Thanks all for the input. Ronnatalie, I think you are right on this one. After I un- wired nutted the white nuetral, and find out there is voltage presents on the neutral, I loosly put them together push back to the box just to get it out of way before I figure out what/how to fix the problem. I went up stair and found out that my kitchen light and garage light no longer functioning (We original think the ceiling box is on the same breaker with living room circuit which is #2) . The kitchen and garage are each tighted to different breaker #1 and 8. "longer functioning" means the fluorescent lights are flicking, can't start up. This probably has to do with my "loosely" tight them together.

Just to be cauouse, I turned off circuit breaker #1, 8 and #2. Once all three are off, that particular neutral wire no longer has any voltage presented.

Since there was no light attached to the ceiling box, we can't be sure which switch controls which lights ( we did as much as possible to lable the switches and outlets to the circuit breakers when we bought the house years ago. Outlets are mostly identified with circuit breaker#, but there are some mystery switches we still don't know what attached to it) I checked the switch right next to the entrance of basement door way which we think it controls or should control the basement ceiling light, except there is no light there yet. It was a most basic switch... two wires red and black on each screw. The white wire is not attached to any , but covered with ele. tape. I don't think the circuits was wired correctly, at least, should not have red and black wire on the switch for single pole. Whoever did the basement finishing and wired this switch probably used the red wire as neutral or ground, I am just guessing, because I did not see any ground wire( either bare or green) at the box in or out from the breaker! Is it possible they use conduit as ground?? I did see whole bunch of red wire were wirenutted together at the box. ( Proper ground the circuits is very important. If I am some how able to confirm the red is indeed used as ground, I will label it or make note to it just in case few years down the road, no more memories left.).

obviously, something is not correctly wired in the circuits. My question is how to/ what I need to do to figure out where is the open/short, or not grounded wire at?? I have multimeter, test bulb, continuety tester, what else tool I need? Consider the difficulty of all the wires travel inside conduit and behind the walls.

    Bookmark   July 6, 2012 at 11:00AM
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If the conduit is metal, then it is probably the ground. The red isn't allowed to be the ground. Only green or bare wires can be.

Sounds like you have a switch loop where the previous owner used the red and black wires. In a switch loop there is no neutral. Google "switch loop" for a full description.

Making loose connections, even if temporary, is a really bad idea.

    Bookmark   July 6, 2012 at 11:47AM
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You seem a bit unfamiliar with multimeter use. A multimeter has relatively high opposition to passing electricity. A light bulb has relatively low opposition.

Let's take an example:
110v on a runner hot wire goes into a switch, then out to a light socket, then through the lamp, out the "neutral" side of the socket on the wire back to the neutral bus.

Now we shut off the light switch, cut the neutral wire in two, connect our meter to the ends of the cut wire, turn the switch back on.

What is the voltage reading on the meter?
Why is this the voltage reading on the meter?

    Bookmark   July 7, 2012 at 10:14AM
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"should not have red and black wire on the switch for single pole."

Could be pefectly fine.

Switches do NOT have neutral connections (though in a switch lop a white wre maybe used as a feed to the switch, it is a HOT WIRE.

They are wired in the 'hot' (black) line to turn things on and off.
An 'always hot' wire often comes in, and a switched hot goes out.
Sometimes a red wire is used to indicate tat the 'hot' wire is switched.

You should probably get a copy of 'Wiring Simplified' by Black and Decker so you will have at least some idea of how thigs are supposed to be wired ad work.

    Bookmark   July 7, 2012 at 11:56AM
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Ron Natalie

Simple snap switches do not have neutral connections. Fancier dimmers or home automation controlled ones may. The later versions of the code require neutrals to be provided to switch boxes in most cases (even if the installed switch doesn't need it).

    Bookmark   July 7, 2012 at 1:18PM
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Excuse me, I am all for helping Do-It-Yourselfers
save a few bucks and take care of problems on their own,
BUT,in this case, it sounds to me as if there are already existing conditions which are terribly dangerous, and a professional should be called in.

    Bookmark   July 7, 2012 at 1:50PM
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Ron Natalie

The existing situation I doubt was dangerous until the diy'er started screwing around with it.

    Bookmark   July 7, 2012 at 5:06PM
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"it sounds to me as if there are already existing conditions which are terribly dangerous"

Far more likely just a lack of understanding of the wiring.

Many folks do not understand the limits of even simple meters, especially digital ones (let alone the 'volt tick' non-contact sensors that are more of a joke than anything useful).

Older analog meters are a little more reliable (slightly higher load currents) but understanding their limits still is important.

    Bookmark   July 8, 2012 at 10:03AM
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Ron Natalie

The other thing is that if you open a grounded connector on a multi wire circuit, there's bound to be voltage present.

    Bookmark   July 8, 2012 at 4:10PM
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Greg, it does sounded like I have a switch loop here which is switching on the hot side. I did not include this possibility initialy. But the problem is not a switch connection. The problem is I have no best way to know which wire is connected to which switches or outlet, especialy there are muilti-circuits tighted together ( another word, I try to figure out how the circuits are connected) . My initially thought was only one circuit which make sense to me for it is in the basement, not much power needed there.

I doubt the condition is dangerous. Well, it is dangerouse when you walk when you trip and fall... or you can conside eating is dangerous,you can choke to death... I would say it needs to be cautious when you deal with voltage and current. But as long as you know what you are doing, and know what you need to look out for, any househood wiring is not as dangerouse as you think. Understand the circuits is important as well as having solid grounded wires. My attemp is to find the best way to understand how my circuits are connected together so I can track down if there is open/short somewhere. Once I know where is the problem at , I can fix it. Also, I can go on to add my ceiling light.

ronnatalie, The ceiling box have 5 conduit ( which means 15 wires) in and out. I have no best way to tell which are feed lines from breakers which are not. I suppose I can untight the black wires and test the voltage presents. If the ones has voltage are the current "in" , and the onee doea not have the voltage are the current "out". At this moment, I hate to un-tight the wirenuts of red and black connection at the box. If I do, the box will be looking like a Medusa's hair, a mass. Is there a simply way to sort this out?

    Bookmark   July 9, 2012 at 1:56PM
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If it's true that you had to switch off all 3 circuits before the neutral wire lost power, then I think you definitely have a pre-existing potentially dangerous wiring problem. Two circuits can share a neutral in certain situations, but not three.
If you only had to switch off 2 circuits, then everything may be fine and it's just a matter of figuring out how your circuits run.
Google "shared neutral circuits" for more information about how that works.
As brickeyee mentioned, you should probably read a basic wiring book before tackling this project. With all due respect, you seem to be over your head on this one. Or maybe it's just a language problem (I'm assuming english isn't your native language due to some of the terms you are using).

One tip, if you plan on undoing all of those connections and creating "Medusa's hair", then take a photograph of it beforehand so that you can put it back together in exactly the same way in case you get totally confused and give up.

    Bookmark   July 9, 2012 at 4:34PM
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sounds like the feed is off of a 14/3, you turned only one leg off at the panel and still had stuff that was on, on the other leg of the panel( the other beaker that is feeding the 14/3)so when you disconnected the neutral it is normal to read 120 on the neutral, it is the return of whatever was on, from the other leg of the panel, you are lucky if you had done this live(both breakers still on), upon the disconnection of the neutral you could of put 240v across your still connected devices.Sounds like a normal split circuit, always turn off both breakers before working on this stuff.

    Bookmark   July 10, 2012 at 7:48PM
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