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12-3 question. #38830 06/03/04 04:39 PM
Joined: Nov 2002
Posts: 558
ga.sparky56 Offline OP
Here's the problem. I have 2 3-way switches controlling a light. House is 3 yrs old,everything was fine until about a month ago. Customer complained that light would not turn off.

Went to check it and found the wiring arrangement to be correct,but upon taking the dead end 3 way out,I discovered that there was 120v between all three wires and ground.

Took both 3 ways out and also took the 3 wire out of the ckt.Ohmmeter says they're all in contact with each other somewhere.

My question is this,What could have happened to the cable to cause this? I did the work and remember running the cable myself. I'm always careful about stapleing,sharp edges,nail guarding etc. No work has been done in the house,or anything else done that would have come anywherenear the cable.

It worked for nearly 3 years. It's got me puzzled as to what happened.


[This message has been edited by ga.sparky56 (edited 06-03-2004).]

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Re: 12-3 question. #38831 06/03/04 05:02 PM
Joined: Oct 2000
Posts: 3,964
Bill Addiss Offline

I had this same problem once. After questioning the Customer when the light started staying on I found out that it happened the day someone put in an AC unit through the wall. One of the screws they put in went through the cable between the Live and 2 travellers and was not touching the bare ground.


Re: 12-3 question. #38832 06/03/04 05:16 PM
Joined: Dec 2003
Posts: 751
earlydean Offline
I had a similiar senario: Homeowner decided to panel his den using 4-inch tongue and groove strips. He ran out of nails. He used what he had in the garage, 4-inchers. Of course he ran one through the NM. I found it by checking every nail with my volt meter till I hit a hot one. They never tell you what they did, though. It is assumed to be your fault because you wired the sucker.


Re: 12-3 question. #38833 06/03/04 07:37 PM
Joined: Mar 2004
Posts: 774
BigB Offline
Ditto here. My customer hung planter boxes under the windows using 3 inch screws on the brackets.

Re: 12-3 question. #38834 06/03/04 08:54 PM
Joined: Nov 2002
Posts: 558
ga.sparky56 Offline OP
Thanks for the input fellas.

The only thing I could think of was that is one of the switches is on the outside wall,and possibly a siding nail hit the wire.

I'll check closer for "improvements" when I go back.


Re: 12-3 question. #38835 06/04/04 12:09 AM
Joined: Oct 2000
Posts: 3,964
Bill Addiss Offline

Ask them if they remember the Breaker tripping at all, and what was going on at the time.

It's worth a shot. In my situation the Breaker did trip when the guys were working, but then it did reset.

let us know how you make out.


Re: 12-3 question. #38836 06/05/04 07:10 AM
Joined: Nov 2002
Posts: 558
ga.sparky56 Offline OP
Well, I wound up going in the attic a nd fishing a piece of 12-3 into both switches.

I couldn't find any evidence of anything that would have caused this to happen.

They say the breaker never tripped,nor could I get it to trip with the old 3-wire,but feeding any of the 3 insulated wires in the cable made them all hot.

It's fixed,but I still don't have a clue as to what could have happened that took 3 yrs to show up. [Linked Image]


Re: 12-3 question. #38837 06/05/04 10:42 AM
Joined: Feb 2002
Posts: 840
CTwireman Offline
I have gotten voltage across a 3-wire before due to induced voltage on a multiwire circuit (one phase deenergized), but never a full 120 volts. That is really strange.


Re: 12-3 question. #38838 06/05/04 01:02 PM
Joined: Jun 2003
Posts: 1,143
DougW Offline


When In doubt, blame "The King".


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