OK 4Lorn, Bill, IBEW, and other elec gurus… mea culpa, I made a rookie mistake compounded by a wierd situation.
I was finishing the installation of the additional work on the 3 way circuit I was talking about the other day. I’m replacing the existing light fixture in the stairwell, as well as adding lights to the circuit. Got everything run and dropped the original fixture to find that in the ceiling box there were (4), 2 conductor BX cables (so tight they must’ve pounded em in there with a mallet). I began teasing them apart to figure out what I had and it became obvious I was going to have to cut them back to clean them up, transfer them into a bigger j box, and run a short line to a new ceiling box.
Now, I was very sure I was keeping tracking of what was nutted to which but these are old cloth covered BX and my notes ummmm… didn’t survive. So I have to chase them down and figure out where I’m at. Ordinarily I wouldn’t have any problem doing some quick continuity checks, but here’s where it gets even wierder (to me). I discovered that one cable feeds the other (unswitched) lights in the hallway, so with the cable that is the power feed I now have (2) 2 conductor cables constituting a 3 way circuit, as far as I can tell. I’ve never seen a 3 way circuit without a traveler, any suggestions how to sort out this mess?
Thanks!
PaulB
Edited 3/15/2005 4:10 pm ET by PaulB
Replies
"I discovered that one cable feeds the other (unswitched) lights in the hallway, so with the cable that is the power feed I now have (2) 2 conductor cables constituting a 3 way circuit, as far as I can tell. I've never seen a 3 way circuit without a traveler, any suggestions how to sort out this mess?"
Well it is possible that some one else did what you where contemplating, but new not to do.
That is they cheated and used the ground on the BX as one of the lead.
However, that would have probably been clear that it was wired very strangly when you opened up the box.
Here is my first guess. One cable is supply, one is a feeder to supply power to a downstream lights or receptacles (or to another light that is switched with this one), and the last one is a switch leg that goes to one of the 3 way's and 3 wire between the 2 3-ways switches.
If you open up the switches you should find one with one 3 wire cable and the other with a 3wire cable from the other switch and a 2 wire to the light box.
If you have a tone generator/probe you can go this a little quicker.
But without it start by separating all of the cables and wires.
Then put power on the circuit and ID the supply. Then mark that and set it asside. Verify that there is no power on the other two.
Then turn the power back off, just be be safe.
Then try one of the other cables and connect a continuity tester/ohm meter between the 2 wires. Then try one of the 3 way switches (unless there is some question about whether they are woring correctly or not).
As you operate the switch the tester should alternate between open and short.
If it doesn't then try the last cable.
Then mark that cable as being the switch leg and set it asside.
The last cable is then feed to downstream lights/receptacle.
Thanks Bill,
I know which one is the supply, and which one feeds the downstream circuit. But where I'm really stumped is that all cables are 2 conductor. There are no 3 conductor cables. I have a tone gen, etc and ordinarily wouldn't have any trouble sorting this out but the lack of a 3 conductor cable has me ummmm... befuddled.
Oooops, on rereading your post I see where my logic went wrong, I think...but there is still a 2 conductor cable that remains unaccounted for. Maybe it feeds sumthin else, oyyyyyyy. That's what I get for trusting myself to keep it straight in my head as I was disasembling it.
Thanks for the suggestions!
PaulB
Edited 3/15/2005 4:53 pm ET by PaulB
Edited 3/15/2005 4:56 pm ET by PaulB
1- Get you a book of number strips. Label each involved wire.
2- Using a piece of paper, draw yourself a diagram.
3- Identify [trace] each of the involved wires.
4- Use the grand theory of switches and figure things out. Wrap a piece of pink tape on each incoming power line.
~Peter
Believe me PM, I alwaysssssssssss do that. Actually in my previous business, we used things called twin checks, little stickers that came in two matching pieces. (Next time you get a roll of film done, look at the envelope and you'll see one on it, and a matching number on the film sleeve). In this case, the insulation crumbled as I was disassembling the connections taking my numbers with it, and I made the fatal mistake of thinking I was keeping it straight in my head... last time I'll do that, if for no other reason than embarassment ;)
PaulB
This is a good puzzler, and I'd like to hear what you finally figure out. Is it possible that they used a piece of 2-wire for travellers and another for the common?
Scott.
Bill had the key Scott. My mistake was assuming that all the conductors they pounded into the J box were associated with the light fixtures. The one that had me stumped actually fed a circuit on the floor below. Combined with the fact that this was the one of the 5 (I think) possible ways of wiring a 3 way circuit I had never seen before, I was really thrown for a loop.
And if I wasn't grateful enough earlier...thanks Bill!
PaulB
Someone cheated and used two 2-conductor cables instead of one 3-conductor cable.