3 way Switch Throwing Breaker

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Old 12-03-07, 07:14 PM
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Question 3 way Switch Throwing Breaker

I bought a house that had a 3 way switch hooked up incorrectly. After hooking up the common on the correct terminal on one switch, the light worked correctly. However, now the breaker occasionally throws. This never happened before I switched the wires around. I can flip the switches a hundred times and it works fine. Then the next time the breaker throws. I checked both switch boxes (plastic) and the are fed by a 14-3 line and no loose wires or signs of shorts. I pulled the cover on the box for the light (plastic) and no signs of of any shorts there either. Either switch can blow the breaker and usually their is a small flash in the switch when that happens. Any suggestions would be greatly appreciated. Thank you.
 
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Old 12-03-07, 07:30 PM
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Make sure that the switches are nowhere near the metal sides of the box. Make sure that the neutral wires (if present in the box) are properly wire nutted with no bare copper exposed. Make sure that the ground wires are well away from the hot terminals of the switch.
 
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Old 12-03-07, 07:34 PM
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Does "occasionally" have a pattern? Or is it truly random?

Check everything Bob mentioned, but also consider that it may have been wired correctly before. There are a lot of equally correct ways to wire a 3-way switch, and perhaps it was just wired in one of the ways you're not familiar with.

How did you determine that it was incorrectly wired anyway?
 
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Old 12-03-07, 07:52 PM
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Thanks for the fast response. All three boxes are plastic and there are no signs of arcing inside the boxes or on the wiring. The two switches are in 2 and 3 gang boxes with lots of room around the conductors. It is random. I used the switches many times testing it and it would work fine and then the switch would spark and the breaker blow. As far as it being wired incorrectly, if switch A was in the down position, switch B would not turn on the light. I also used a tester and found one of the traverlers hooked up to the common terminal. The light is working properly now with the exception on the random short. Could it be one of the switches? If I did hook it up wrong, could I have done so in such a way that I would be blowing the breaker? Thanks again.
 
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Old 12-03-07, 08:12 PM
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Any chance this is an AFCI or GFCI breaker?

Switches cannot normally trip ordinary breakers, unless they somehow internally short one of the conductors to ground. This would be very unusual fault.

Can you trip the breaker by wiggling the switch from side to side without flipping it?

In any event, I'd probably buy a new switch.
 
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Old 12-03-07, 08:35 PM
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No, this is just a normal 15 amp breaker that has this problem entry hall light, the adjoining bathroom fan, and the front entry light on it. I tried wiggling both switches and they seem solid (and working properly at this time). Both switches at one time or another have blown the breaker. I can't isolate a problem switch. There clearly is no short in the conductors in there respective boxes. Does this mean I should look to the box up at the lightfor the short? I didn't touch the light until this problem but there are a lot more wires to cause the problem up there. Would it have to be either in the switches themselves or the light that is causing the short? Thanks.
 
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Old 12-04-07, 05:04 PM
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I removed and replaced both switches with new premium 3 way switches, same problem. Right now in the current switch positions I have the short and the breaker trips as soon as I set it. I have the switches out of there boxes and I have all the wires in the light box pulled out. Is there any way to use a tester to isolate the short. Right now each switch box has just four conductors to the respective switches. Switch A has a white and black traveler and a red common. Switch B has a red and black traveler and the white is the common. The light box has six connections: white/white, red/black, black/black, 3 ground wires, white/light conductor, red/light conductor. Any suggestions would be appreciated as I have ran out of ideas. Thank you.
 
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Old 12-04-07, 06:11 PM
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If the problem is not at the fixture, and not at the switches, then the only thing left is the wiring in the wall. Perhaps somebody put a nail or screw through it while hanging a picture or mounting a bookshelf.
 
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Old 12-04-07, 08:17 PM
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Maybe try replacing the light fixture with a keyless lampholder and see if it still trips. Also maybe bypass the switches all together by splicing through them and keep the light on. Are you 100% sure that the circuit is not overloaded? Is the breaker warm at all? Know anyone with a clamp on meter to check current? Does it happen right away when to turn on the switch or will it happen after a little while?

Hold the phone!! I don't think you have this wired correctly. here is what you posted for how it is wired:

"Switch A has a white and black traveler and a red common. Switch B has a red and black traveler and the white is the common. The light box has six connections: white/white, red/black, black/black, 3 ground wires, white/light conductor, red/light conductor."

Do you have the commons from each switch wired to the light? I think your travelers are also messed up. You have a red and a black on one set and a white and a black on the other. I'm guessing your light box has two 14/3's and one 14/2. Is this right? If so, here is how you should have it wired:

Find your hot. (14/2 in light box) Connect that to the common of one switch. The black/red splice. Make sure this is correct and that the black is also with the white wire that is connected to the light. That should be the neutral. Check that to ground to make sure. Should be 0 volts. Then connect the black and white from the 14/3's for your travelers on both switches. The last red is connected to the common of the other switch and that goes to the black of your light. I hope this makes sense. Try that and see if it works. Some how I think the light is wired in series and the bulb is the only thing that is resistance to current flow. Thus, overload.
 
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Old 12-05-07, 06:57 PM
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I have seen some crazy three way switches wired unconventionally. They worked before replacing the switches but if you did not write down the scheme you were in trouble. This has nothing to do with the problem here but just adding my thoughts. <p>Sounds to me maybe the light fixture.
 
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