Three Way Switch Problem

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  #1  
Old 08-19-04, 02:28 PM
Bob Stern
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Question Three Way Switch Problem

This is similar to a past question but with a variation. I have a two switch setup for my upstairs hall fixture. Quite suddenly I found that one switch will operate the light while the other won't. Sometimes its the upstairs switch, sometimes the downstairs switch. I'm getting lots of excersize running up and down the stairs to turn on that light! What should I do? Thank you for any help you can give me.
Bob
 
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  #2  
Old 08-19-04, 03:06 PM
J
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You say "suddenly" so I assume this means that nobody did anything or changed anything. You certainly have to think about whether or not anybody even hung a picture in the area that might have hit the wire.

You also say that it doesn't work. Is this true regardless of the position of the other switch? The common complaint is that switch "B" won't work unless switch "A" is in a certain position (up or down).

One possibility is that a connection has failed. Backstab connections (wires poked into holes) often fail. You might try moving any backstabbed connections (release them with a small screwdriver) on the switches to the adjacent screw. If the adjacent screw already has a wire, you'll need to use a wire nut and pigtail.

Yet another possibility is that a switch failed. Buy a replacement switch. Don't just move the wires from the old switch to the new switch by screw position. That's not a reliable algorithm. Find the black (i.e., common) screw on each switch and make sure the wire connected to the black screw on the old switch connects to the black screw on the new switch.

Shut off the breaker before doing anything, and work carefully.
 
  #3  
Old 08-20-04, 01:16 PM
Bob Stern
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John-
Thanks so much for your reply. No, no one did anything or changed anything to make this happen. It just did! I'm not certain if switch "B" won't work if switch "A" is in a particular position, but I'll check (ohhhhh, those stairs!) I figure that perhaps I should replace both switches, if you think that its a good idea - just to be safe. I figure the switches are at least 20 years old. I will certainly follow your instructions. Thanks again.
Bob
 
  #4  
Old 08-25-04, 02:27 PM
Bob Stern
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Unhappy Still Problematic!

I replaced both switches following the guidelines kindly suggested by John, and the problem is still there. My observation is: If Switch A is turned on, and if Switch B turns off, Switch A no longer operates. If Switch B turns on, and Switch A turns off, B no longer operates. I'm confused.
The fixture in question is now holding 2 "power saver" (read flourescent bulbs with Edison bases) which I don't see making any difference. Any further help will be more than highly appreciated.
 
  #5  
Old 08-25-04, 05:08 PM
J
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This is the common symptom of a misidentified common on a 3-way switch. If the problem had started when someone replaced a switch, then I'd conclude that the wires had been incorrectly transferred to the new switch. This is a very frequent mistake. However, this started without anybody doing anything. So it sounds like a connection of one of the travelers failed.

Are the symptoms with the new switches exactly the same as the symptoms with the old switches? This is important. It's possible that the new switches fixed one problem and created another.

Did you carefully move the wire on the black screw on the old swithes to the black screw on the new switch, even if that screw was in a completely different position on the switch?

This problem would be trivial to solve if not for the "suddenly" in your original post.
 
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