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Got a tingle from a neutral wire today ... please help me find the source

Got a tingle from a neutral wire today ... please help me find the source

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  #1  
Old 04-14-14, 05:57 PM
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Got a tingle from a neutral wire today ... please help me find the source

OK, here's the scenario:
A couple months ago, I replaced the recessed light above my kitchen sink. It was original (1972), and the grounding was via metal conduit wired directly into the junction box. One hot black wire, one white neutral. Cloth-wrapped.

Because my new recessed fixture was rated for NM-B (90 degree centigrade) cable only, I ran 14/2 NM-B for a good 2 or 3 feet out of the junction box and installed the new light. I was careful to note how the original individual wires were arranged, and marked them with tape so I could re-do them properly. Oh, I also replaced the metal J-box with a bigger since it seemed overcrowded with the new wiring.

Now, coming into this J-box are (what I thought were) 2 different circuits. One (#15) supplies only this over-the-sink light plus the overhead light in the kitchen. The other circuit which passes through this box (#17) supplies a couple of other rooms in the house.

When I originally replaced this fixture, I turned off all the breakers in the house, other than the gas furnace breaker (it was cold!) No issues.

Today, while changing the light bulb, I decided to pull the box out and just have a look and make sure everything was nice and tight and good. I wanted to trim down the neutral wires a bit, because there was a little copper exposed under one of the neutrals, and I'm anal. Also wanted to mark the box as containing two circuits for future homeowners, for safety.

I undid my twist of all five neutrals, and started to even them all up for a nicer connection. I was very surprised (shocked?) to get a little tingle from one of the neutrals. Just one, out of the five. My NC voltage tester read that wire as hot. I started to try to isolate the problem, and when I switched off circuit #23 (which supplies an adjoining room, the dining room), it killed the tingle wire.

So it seems I have two (and part of a third) circuits coming into the box. Turning off breakers #15 and #17 kill all the hot wires. But ONE neutral wire still is live, and turning off breaker #23 kills that one.

Can you help explain to me how this could be? Please see photos.
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Thanks!
Carol
 
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  #2  
Old 04-14-14, 06:06 PM
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Forgot to mention that while working today, I ONLY turned off circuits 15 and 17, which I was confident were the only ones running into/through this J-box. Evidently, circuit #17 has a neutral going in there, somehow, which is quite puzzling. Thanks.
 
  #3  
Old 04-14-14, 06:07 PM
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An open neutral will shock the same as a hot if you are between the open and the panel.
 
  #4  
Old 04-14-14, 06:16 PM
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Mild tingle only ... but why? And how to fix?

Thanks for the reply PCboss, but I need to know why it's happening and how to fix it. Or if I even need to worry about it, since everything seems to be functioning properly. I can supply more information, if needed.

As I said, it was just a mild "tingle" when I grabbed the wire, not a big shock.

Thanks!
 
  #5  
Old 04-14-14, 06:33 PM
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You've got a lot going on there and some clean-up to do.

First - the box is supposed to be securely mounted. The cables are also supposed to be secured within 12" of the box unless fished.

Biggest problem is that those neutrals are supposed to be separated per circuit. Maybe it is the same way in other locations as that is why you got the tingle.
 
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Old 04-14-14, 06:58 PM
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Hello Astuff, and thanks for the reply.

The box is not secured because the access is through a 5-inch recessed lighting opening. If it was secured, there would be no access.

I did attempt today to separate the neutrals per circuit. The lights failed to work that way.

:-(
 
  #7  
Old 04-14-14, 08:10 PM
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Are you sure you have the two breakers correct ?

You've got all the whites tied together which means you have a multiwire branch circuit. Two circuits on two breakers and sharing the same neutral. The two breakers MUST be next to each other for it to work properly.
 
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Old 04-15-14, 07:25 AM
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I missed that - if you have breakers 15 and 17 - should be next to each other as PJmax said and have a 3 conductor plus ground cable running from panel. Newer codes require tying the handles together or a two pole breaker so that you know what's going on.

For finding the tingle - Could be the neutral on that circuit is tied in another box. Other possibility is induced current (cables running parallel pick up stray voltage). Check the other boxes for circuit 23 does not connect to neutral of 15/17.
 
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Old 04-15-14, 08:58 AM
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the grounding was via metal conduit wired directly into the junction box.
I am still wondering how you are able to drop the box down if it is connected to conduits which are carrying the ground to the box.
 
  #10  
Old 04-15-14, 10:54 AM
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Joe,

The box was only connected to the one flexible metal conduit attached to the old can light, providing ground to the can only. That was the original installation. I removed the entire old can light with its attached conduit and replaced it with a brand new can light, and new Romex with green wire ground to the can.

It's a strange situation with the unmounted junction box and cabling being up in the ceiling. The original 1972 electrician installed it this way. When we moved in several years ago, the kitchen light switch turned on both the overhead light and the over-the-sink light simultaneously. I wanted them on separate switches, so we had an electrician come in and fish new cable to the over-the-sink light and install a switch to it. So two separate electricians have worked on this.

The original installer mounted a metal ring for the can to slip into, between two heavy boards up in the "hole." Nailed in, and I couldn't get them out without tearing up the ceiling. Neither the J-box nor the cables up there are secured to anything, the theory being I guess that if they were secured, they wouldn't be accessible through the 5-inch can light opening. There is a fair amount of slack in all the cables, which is how I'm able to get everything dropped down to work on it.
 
  #11  
Old 04-15-14, 11:08 AM
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Astuff and PJ,

Yes, breakers 15 and 17 are adjacent. I did figure out that it was a multiwire branch circuit, and I'll make sure to get the handles tied together or replace with a two pole breaker.

Could you provide a bit more explanation regarding finding the tingle?

For finding the tingle - Could be the neutral on that circuit is tied in another box. Other possibility is induced current (cables running parallel pick up stray voltage). Check the other boxes for circuit 23 does not connect to neutral of 15/17

Since the tingle stopped after turning off breaker #23, should I check all the boxes serving 23? How will I know that anything in those boxes connect with neutral of 15/17? Sorry for being dense, I just can't seem to think this through.

To reiterate, everything is working fine, no dimming or brightening of lights or tripped circuits. I'm mainly concerned about it being hazardous.

Thanks!
 
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