Replies

1. 
   webby | Dec 03, 2007 04:17am | #1

   Criddle what I have done in the past is to disconnect the wires and seperate them then turn the power back on and use a non contact voltage indicator to identify the hot.

   I am not an electrician so someone else may have a better idea. What I have done works in basic simple situations.

   Chris Webb

   Chris' Handyman Service

1. 
   criddle | Dec 03, 2007 04:27am | #2

   OK, getting closer.  I can at least now identify 2 of 3 that are hot.  Thanks for the easy check!

1. 
   northeastvt | Dec 03, 2007 05:44am | #10

   criddle,

     If two are testing hot, try flipping the other three way, and test again. The one that stay's hot, "should" be on the common (black screw).The other two will test hot back and forth when you flip the switch, they should go on the brass screw's. Just a thought.

   Northeastvt

2. 
   JTC1 | Dec 03, 2007 04:38am | #3

   I use a cheater cord and a continuity meter.  My cheater cord is nothing but a 75' length of #16 wire with alligator clips on both ends.

   Turn off power.

   Disconnect all conductors at both ends.

   Check all conductors for "no power" state with non-contact voltage detector.

   Clip alligator clip to one conductor at one box. Run cheater wire to other end of cable run - determine which conductor has continuity with your cheater wire - code this one somehow - white tape = neutral.

   Attach clip to another conductor and code it something else - go to other box - code the wire which is currently clipped white to match other end - remove alligator clip and find continuity again.

   Keep checking continuity and coding the wires until you run out of conductors.

   Jim

   Never underestimate the value of a sharp pencil or good light.
1. 
   criddle | Dec 03, 2007 04:48am | #4

   That makes sense even though a bit of a pain!  I wonder how they wired anything when it was originally installed?  I stripped back more of the sheath and I don't see any color differences.  For that matter, it appears they made 12-3 cable with no ground wire in it.

   Edited 12/2/2007 9:18 pm ET by criddle

2. 
   pwd | Dec 03, 2007 05:17am | #5

   Why do you use a non contact tester?

1. 
   criddle | Dec 03, 2007 05:22am | #6

   I'd rather check for power without actually touching it.  Sorry, I'm a chicken.

2. 
   JTC1 | Dec 03, 2007 05:25am | #7

   At that point in my process, as described, I should not have any reliable neutrals or hots - this system does not have a ground - so non-contact tester becomes the fastest, easiest way to be sure I have not missed a hot wire which could bite me - not good for my health.

   Continuity meters generally do not like being connected to energized wires - not good for their health.

   Jim

    Never underestimate the value of a sharp pencil or good light.

3. 
   edlee | Dec 03, 2007 05:28am | #8

   Ya know in all the years I've been an electrician I can't remember ever seeing NM cable that wasn't color-coded inside. 

   Sometimes the colors fade a lot and go pretty dark , but even then good bright light usually clears it up.

    

   Ed

1. 
   criddle | Dec 03, 2007 05:35am | #9

   How far back would you guess I should go to see color?  I've really only stripped it back a couple inches.

1. 
   edlee | Dec 03, 2007 05:44am | #11

   I dunno, if you have the slack try 2 or 3 more inches. Are you still just trying to repair your 3-way switching, or is this a more general question? 

   Cuz if it's 3-way repair, then the color-coding often doesn't really mean much and you don't need it. Just turn off the circuit, use a continuity tester to sort out the individual wires and then label them.

1. 
   criddle | Dec 03, 2007 05:49am | #12

   It is a repair and you are right.  I just need to buzz this out and stop trying to avoid it!

2. 
   northeastvt | Dec 03, 2007 05:55am | #13

   Edlee,

      I have seen some up here. Maybe it was the next step after knob & tube? Most of it end's up terminating in three inch round/octagon boxes with cloth tape covering the connections. And usually with no cover on the jbox, with insulation over the top of it...I'm sure you have seen your share of thing's like that :)

    

   northeastvt

1. 
   edlee | Dec 03, 2007 06:00am | #14

   I'm sure you have seen your share of thing's like that :)

    

   Oh yeah. The wiring is crammed in there, the splices are often soldered and wrapped with cloth tape and the insulation so old that if you pull the connections out it's all brittle and cracks apart. And most of the time it's in damp dirty basements or old dairy barns with undefinable  crud everywhere.........

   Yuch!

    

    

   Edited 12/2/2007 10:01 pm ET by edlee

1. 
   criddle | Dec 03, 2007 07:48am | #15

   The only difference I have is it is in a dry attic space, but the brittle part and tons o' tape part explains it all.  It makes sense about the next step from knob and tube.  You should have seen the jerry-rigged exterior fixture I am replacing.  It is amazing that it has lasted all these 59 years.

1. 
   DaveRicheson | Dec 03, 2007 01:55pm | #16

   is it is in a dry attic space

   Cut it back far enough to find some color on the individual wires (per edlee) and add a j-box or two as needed. As long as you can get to it, you can add a long splice and give yourself plenty of wire to work with in the new boxes.

   Chances are the old wire insulation is so brittle inside the existing boxes that it will just crumble as you try to make up new joints.

   Just keep your new j-boxes accessable and be sure to but a cover on them.

    

   Dave

4. 
   DanH | Dec 03, 2007 02:25pm | #17

   I would bet that if you look closely one of the wires is "distinguished" by a different color thread in the wrapping or a small ridge on the plastic insulation. But that's not to say that the sparky would have paid any attention to such things.

   Simplest thing is to use a neon tester: With the circuit hot you stick one lead in the slot and hold the other in your hand. The slot that lights the tester is hot. If both sides light the tester dimly, or neither side lights it, then the circuit's disconnected.

   If your view never changes you're following the wrong leader
1. 
   DaveRicheson | Dec 03, 2007 04:24pm | #18

   I use to recommend that same technique,..... got hammered for it here, several years ago.

   BTW, it scares the **** out of my wife when I touch a hot wire with one lead while holding the other lead. Then if I let the smoke out of something, she says I have a death wish :)

    

   Dave

1. 
   DanH | Dec 03, 2007 06:30pm | #19

   It's perfectly safe, more or less.
   If your view never changes you're following the wrong leader

2. 
   BillHartmann | Dec 03, 2007 07:25pm | #20

   I did not give that as a recommindation, but mentioned that I did that here and lots on comments. Mainly htat it would not work.Another way is to go back to a good know receptacle and plug in an extension cord.Then take the other end to the problem area. You can get real accurate data that way on both hots, neutrals, and opens by meauring between both the hot and neutral and the wire in question.But I misplaced by 79cent neon and got a $3 one with two bulbs, one lighting for 120 and the 2nd for 240.That drew enough current that when I plugged my extension cord into a GFCI that it tripped the GFCI..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.