3 way light switch problems

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  #1  
Old 12-07-01, 03:19 PM
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3 way light switch problems

I have a ceiling fan with a seperate light switch. The light is controlled by two switches on opposite sides of the room (3-way switches)

All of the sudden one of the switches does not work if the other one is off.

Why and how do I fix this?

Any help greatly appreciated
 
  #2  
Old 12-07-01, 03:34 PM
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Chances are that a connection has come loose at one or the other of the switches. Shut off the breaker and check the connections. If the switches are connected using the push-in connectors on the back, move the connection to the adjacent screw. Be careful not to mix up the wires or you may make the problem worse.
 
  #3  
Old 12-07-01, 03:36 PM
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That was my first thought also so I actually replaced both switches and the situation did not change. Any other suggestions? I am really stumped
 
  #4  
Old 12-07-01, 03:54 PM
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Oh. You should have said so in the first place.

Did you pay careful attention to which wire was connected to the "common" screw on each switch? If you just put the new wires on the new switch by matching screw position, then that is undoubtedly the source of your problem. Different switch manufacturers put the common screw in different places.

Your symptoms are the classic symptoms of a common wire on a traveller screw.

If this sounds likely, post back and I'll give you some suggestions on how to debug this situation.
 
  #5  
Old 12-07-01, 04:01 PM
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I removed the 2 main wires first and put them on the new switch and then did the 3 wire on the other side. I tried to be as careful as possible to put the wires on the correct sides.
 
  #6  
Old 12-07-01, 04:02 PM
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By the way the switches are leviton heady duty grounding 3-way switches if that helps

Thanks Again
 
  #7  
Old 12-07-01, 04:09 PM
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Being sure to put the wires on the correct sides is exactly the wrong thing to do. As I've said, there is no standardization of screw position.

Look at the three non-grounding screws. Is one of them a different color than the other two. That one is the "common" screw. Do you still have the old switches? If so, do the same thing with those.

What did you discover?

Now tell me the wire color of the wires attached to each screw.
 
  #8  
Old 12-07-01, 04:17 PM
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You are right. There is one screw that is a different color. The wires are black white and red. I am going to redo the wiring and put the red wire on the 1 different color screw right?!?

I can't do it till in the morning but will try first thing

Thanks
 
  #9  
Old 12-07-01, 05:01 PM
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Where did you get the idea that the red wire is the right one for the common screw? It might be, but we've seen no evidence of that. I think you're jumping to conclusions.

If you would rather experiment than troubleshoot, that's fine. If you have the patience, you can try all combinations. There are three possibilities at each switch for the correct common wire, and thus only nine possibilities to try.

If you'd rather troubleshoot than experiment, then get out your voltmeter or circuit tester.[list=1][*]Shut off the breaker.[*]Remove both switches and separate all three wires in both boxes.[*]Turn the breaker back on.[*]Conduct six tests for voltage, one between each of the six wires and the known ground. Hopefully, exactly one will test hot. This is the "common" wire for that switch. The other two wires are the travellers.[*]Shut off the breaker again.[*]Now add the switch to the box that had the hot wire, connecting the hot wire to the common (usually colored black) screw on the three way switch. Connect the two travellers to the other two brass screws.[*]Turn on the breaker again.[*]Now go to the other box and test all three wires for hot. Hopefully again only one will be hot. This wire is one of the two travellers.[*]Go to the first switch and flip it to the other position.[*]Go back to the box and test the remaining two wires. Again, one will be hot. This is the other traveller. The remaining wire that did not test hot with either position of the switch is the common.[*]Shut off the breaker.[*]Connect up the other switch, connecting the common that you found to the common terminal on the switch, and connecting the two travellers to the two brass screws.[/list=1]
 
 

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