Strange wiring of two switch loops


  #1  
Old 10-23-04, 06:41 PM
mattgg
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Strange wiring of two switch loops

I replaced a dimmer today and ran into some wiring that makes no sense to me. The box has two switches. There are two 14/2 + ground cables coming into the box. The first switch is connected to the black wire from cable A and the white wire from cable B (there is black tape on this wire). The second switch is connected to the white wire from cable A and the black wire from cable B. So the power comes in on cable B (both wires are hot) and switched power goes out on cable A. I expected to find normal switch loops (power in on black and switched power out on white in the same cable).

I have no idea how this would work, except it does. Does this make any sense or did someone really screw up the wiring at the fixtures? There's no neutral in the switch box. There's no reason to have two hots.

One clue is that cable B does not appear to be stapled (there was a lot of slack in it), while cable A is stapled. Maybe they had to pull a new cable to make it work, though I still don't see how this could have happened. I haven't opened up the fixture boxes yet because neither of them is very easy to get to.

Does this make sense to anyone?
 
  #2  
Old 10-23-04, 06:59 PM
R
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This does not make sense to me. I hope that these fixtures are on the same circuit. Please do investigate the fixtures and report back as to the wiring there. I am concerned that someone may have added something and made a very bad mistake.
 
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Old 10-23-04, 07:11 PM
J
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I think somebody replaced the switches and got the wires mixed up. I suggest you put both wires from cable A on one switch and both wires from cable B on the other switch.

By the way, if you make the modification I suggested, then the wiring makes perfect sense.
 
  #4  
Old 10-23-04, 07:27 PM
rsierk
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I agree this is very bizarre indeed!

Can you get to the switched devices and feedback to us what wires are in those boxes?

What are these switches controlling, lights or outlets? I take it at least one switch is controlling a light since you made mention of changing out a dimmer.

You make mention that wire B is loose: was one swtich there before the other?

We have to find the power source from the panel. Doesn't seem to me that either of these 2 wires are from the panel, otherwise there would be a nuetral; and it seems by your description that all wires (both blank and white) are hot, correct?

Rob
 
  #5  
Old 10-23-04, 07:53 PM
mattgg
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Originally Posted by John Nelson
I think somebody replaced the switches and got the wires mixed up. I suggest you put both wires from cable A on one switch and both wires from cable B on the other switch.
That was my first thought and I tried it, but neither light worked when wired that way.

The fixtures are on the same circuit. I won't be able to investigate the wiring at the fixtures right away because I have two babies and no time. I was lucky to find the 20 minutes to replace the dimmer. It took so long because there were at least three code violations in the box - more than 1/4 inch of sheating on the cables, grounds not tied together, and two grounds under one ground screw.

I'll post back later when I know what the wiring looks like at the fixtures.
 
  #6  
Old 10-23-04, 08:01 PM
mattgg
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Originally Posted by rsierk
What are these switches controlling, lights or outlets? I take it at least one switch is controlling a light since you made mention of changing out a dimmer.

You make mention that wire B is loose: was one swtich there before the other?

We have to find the power source from the panel. Doesn't seem to me that either of these 2 wires are from the panel, otherwise there would be a nuetral; and it seems by your description that all wires (both blank and white) are hot, correct?
Both switches control light fixtures.

It is possible that one switch was added later. I can check with my neighbor to see how many switches he has. Our houses are identical and he hasn't done a lot of work on his so he probably has the original wiring in this switchbox. The previous owners of my house had lots of work done by incompetent people (one "plumber" ran a drain pipe to a sump pit and let the pump dump the waste in the backyard).

Both wires in one of the cables are hot. The wires in the other cable bring switched power to the fixtures.
 
  #7  
Old 10-23-04, 08:03 PM
G
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What happens if you cap off one of the hots and make a pig-tail from the other hot to both switches?
 
  #8  
Old 10-23-04, 09:09 PM
J
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Both wires in one of the cables are hot. The wires in the other cable bring switched power to the fixtures.
Well, that explains why my solution didn't work.

Since you said that it works, and you said that both lights are on the same circuit, I'd just leave it alone. It doesn't meet code and it is definitely unusual and it cannot have been wired by a competent electrician, but it doesn't sound particularly unsafe.
 
  #9  
Old 10-24-04, 06:05 AM
mattgg
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Originally Posted by Garou
What happens if you cap off one of the hots and make a pig-tail from the other hot to both switches?
I didn't try that, but I assume it would work. Hot is hot, right? As long as they are on the same circuit (which they are) it should be fine.

I am going to leave it alone, but I want to find out how this happened. I suspect there might be a splice hidden in the wall or ceiling somewhere. If there is, I want to know about it.
 
  #10  
Old 10-24-04, 06:25 AM
G
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It will work as is, but it would be nice to fix it so the person who lives in the house after you doesn't have the same problem.
 
  #11  
Old 10-24-04, 06:30 AM
R
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If there is a splice hidden the wall, you not only want to know about it, you want to put it in a proper junction box.
 
  #12  
Old 10-25-04, 03:58 AM
Snape
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I think the answers will proberbly lie in the way that the fixtures are connected have you had a chance too look at these fittings yet as i see you mentioned you have two little people too look after.

Did you say that cable B has two hot wire coming from it. I can see how this works but as the rest of the guys have said this is a big code violation, it would be usefull to solve this as the next person in the house might not be as wise about electrical fixtures and could be dangerous.

Thanks
Ian
 
  #13  
Old 10-25-04, 08:11 PM
rsierk
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I can empathize with the 2 little ones: I have 2 under 17months right now and things are WILD to say the least. In fact at dinner tonight they both decided that they were going to puke. Two puking babies, one is screaming, and my wife and I are running around trying to clean everything up--one had to be there to appreciate the moment

Please open up the fixture boxes, if you ever get a chance, I would really like to know what is going on. One has to work real hard to wire those switches that poorly; you definitely can't get there with logic.

Is this a first floor application? What is the layout? Are the lights in the same room?

I really think the loose wire is an indicator that this mess was added for some reason. You have to find the power source from the panel. The wire brining power to this switch box is not from the panel, can't be, or else there would be a nuetral along with it.

But another post is absolutely correct: if there's somebody out there that would wire a switch box with such ineptness then who knows what the backend of that circuit looks like. You could have splices in walls which would be something you would want to rectify asap.

Can you tell this problem is bugging me? If you ever figure out the issue please let us all know.

Rob
 
  #14  
Old 10-26-04, 09:05 AM
mattgg
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I'll try to open up the boxes tonight when the kids are asleep. They are the dining room chandelier and an outside light (the dining room has a sliding door to the deck). If we can't figure it out from what's in these two boxes, I don't think we'll be able to figure it out very soon. There are a lot of lights on this circuit and I can't open them all up because many are hard to reach.

I've never mapped out this particular circuit, so I don't know what is upstream of these boxes. The house is a split entry, so the dining room is upstairs with an attic above. This circuit powers the front entry lights, the chandelier in the entry, some kitchen lights, the dining room chandelier, the back entry light, a few outlets in the living room, and the microwave. (I am going to run a new circuit for the microwave eventually.) It also used to power some outlets in the finished basement, but I took them off the circuit. It runs all over tarnation and I have no idea which order it goes in.

We found a hidden splice in the kitchen when we remodeled the bathroom (they share a wall), so I wouldn't be surprised to find another. Do people who hide splices ever think to use wire nuts? They sure don't mind using a whole roll of electrical tape.
 
  #15  
Old 10-26-04, 06:06 PM
mattgg
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I just looked in the dining room chandelier's box. There are two 14/2 and one 14/3 cable in the box. All of the blacks are nutted together, all of the whites are nutted together, and the switched power is on the red wire on the 14/3 cable. If you've followed the story to this point, you know that there is no 14/3 wire in the switchbox.

I'll probably find the other end this 14/3 cable in the outside light that is controlled by the other switch, but it's too cold and dark to look there yet. I still can't imagine how someone could screw this up so badly.
 
  #16  
Old 10-26-04, 06:57 PM
rsierk
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I would doubt the 14/3 goes to the outside light. Usually 14/3 is used in 3-way switches; or to run 2 circuits from the panel sharing one ground, the two hots being on opposite phases of course.

Could there have been a 3-way switch that was taken out to put in a new light?

I think you may have to go into the attic/crawl space above the dining room to get some answers. Hopefully there aren't any taped connection laying in the open, or buried in insulation.

Keep us posted if you find something interesting.

Rob
 
 

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