A 3-way mystery!

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  #1  
Old 01-22-08, 01:21 PM
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A 3-way mystery!

There's a light in my kitchen that's on a 3-way switch. One switch is on the west side of my kitchen, the other is on the east side.

For aesthetic purposes, we decided to replace the west switch with a new 3-way switch. So I tripped the circuit breaker, removed the old switch, and connected the new switch using the same wiring arrangement. I reset the circuit breaker, tested the new switch...and had problems.

I <i>thought</i> I had carefully identified which wire was where in the original switch. Apparently not, and now I'm lost.

The east switch is untouched; looking at the switch from the back the white wire is connected to the upper-left terminal, the red wire is connected to the upper-right terminal, and the black wire is connected to the lower-right terminal (marked "common" on the switch).

If I connect the west switch in the same configuration it works like this:
  • With the EAST switch in the UP position, the WEST switch does nothing (doesn't turn on the light).
  • With the EAST switch in the DOWN position, the WEST switch will turn the light on in the UP position and off in the DOWN position.
  • With the WEST switch in the UP position, the EAST switch will turn the light on in the DOWN position and off in the UP position.
  • With the WEST switch in the DOWN position, the EAST switch does nothing (doesn't turn on the light).
If I reverse the red and white wires on the west switch, things work like this:
  • With the EAST switch in the UP position, the WEST switch does nothing (doesn't turn on the light).
  • With the EAST switch in the DOWN position, the WEST switch will turn the light on in the DOWN position and off in the UP position.
  • With the WEST switch in the UP position, the EAST switch does nothing (doesn't turn on the light).
  • With the WEST switch in the DOWN position, the EAST switch will turn the light on in the DOWN position and off in the UP position.
I've verified that the problem isn't with the new switch; I connected the new switch to another 3-way circuit in the house and it works correctly.

The only thing I can imagine is maybe I damaged a wire when I replaced the west switch? If so, which wire would I be looking to fix?

Help!
 
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  #2  
Old 01-22-08, 01:45 PM
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All three way switches are NOT the same. Just because one 3 way switch has it's common in one place does not mean that another 3 way switch will have it's common in the same place.

Identify the common by either looking at the terminal colors (the common is an odd color) or by reading the indicators on the switch.

Put the common in the right place on each switch and the travelers in the right place and your setup will work.

If all else fails, and you forget what was on the common, there are only three wires that can go on the common on each switch. That means by trial and error you can get the light working properly in 9 attempts total, 3 if you only messed with one switch.
 
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Old 01-22-08, 02:23 PM
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The common wire on the east switch, as well as the common wires on the other two 3-way switches in my house, are all colored black. The side terminal for the common wire on all of the switches all have a black screw in them (the others are brass). Without pulling out the multimeter and testing it, I would therefore believe that the black wire and black screw on the west switch are the common wire/terminal.

And yes, I only messed with one switch.
 
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Old 01-22-08, 04:41 PM
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The black terminal for sure is the common.
The black wire is not always the comomn. In some cases it is a white wire.
 
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Old 01-26-08, 07:35 PM
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I am still having trouble with this. :-(

I found an excellent page describing this circuit and how to troubleshoot it:

http://www.naturalhandyman.com/iip/i...l/inf3way.html

Using these instructions I identified the common, which is indeed the black wire. The common terminals on my switches are black screws, while the traveller terminals are brass screws.

So, again, the common is in the correct place but the switch still doesn't work properly, and swapping the traveller terminals doesn't help.

WTF??
 
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Old 01-26-08, 08:07 PM
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If all else fails, and you forget what was on the common, there are only three wires that can go on the common on each switch. That means by trial and error you can get the light working properly in 9 attempts total, 3 if you only messed with one switch.
 
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Old 01-26-08, 08:13 PM
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Then obviously the common is NOT in the right place. Three ways are not magical. Get the commons right and the light works. it's very simple, as suggested I recommend you just try swapping wires to the common screw until you get it.


If your positive you have the common correct, [which you don't] check the bulb just so your not chasing a phantom problem.
 
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Old 01-26-08, 08:14 PM
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Start Over?

Since the original switch worked fine and you are only replacing for a newer or prettier one, re-install old switch the way it was and see if all starts working again. if it does that lets you know you don't have any breaks in the wire or possible other problems and will allow you to start over and carefully trace you steps. Just an idea
 
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Old 01-26-08, 08:24 PM
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Originally Posted by racraft View Post
If all else fails, and you forget what was on the common, there are only three wires that can go on the common on each switch. That means by trial and error you can get the light working properly in 9 attempts total, 3 if you only messed with one switch.
But I didn't forget what was common. I thought the common was black and it is; the multimeter confirms it. And the common terminal on the switch has the black screw and the word "COMMON" written right next to it. So I definitely have the common wire identified and in the correct location on the switch.

Theoretically that means that I have only two possible options: the red and white wires on the two remaining terminals. They either go on white at the top and red at the bottom, or vice-versa. But neither works properly. And since I never messed with the other switch that eliminates the wiring on that side.
 
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Old 01-26-08, 08:27 PM
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Originally Posted by burkej62 View Post
Then obviously the common is NOT in the right place. Three ways are not magical. Get the commons right and the light works. it's very simple, as suggested I recommend you just try swapping wires to the common screw until you get it.
If your positive you have the common correct, [which you don't] check the bulb just so your not chasing a phantom problem.
Once again: I <b>AM</b> positive I have the common correct. All of the other switches in the house have a black common wire, the switch I removed had the black wire on the common terminal, my multimeter verifies that the black wire is the common wire, and the new switch has a very clear identifier of the common terminal.

But as you seem to have all the answers, I'll ask you: Since the black wire is the only wire that comes up with a 120V current on the multimeter, which wire do you think is the common wire? And since the black terminal on the switch is the only terminal that has "COMMON" written next to it, and it's the only black terminal on the switch (the other two are brass), which terminal do you think is the common terminal? You're so insistent that I have misidentified the common wire and/or terminal, so the answer here (according to you) cannot be "the black wire and the black terminal" so..... What's the answer?
 
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Old 01-26-08, 08:28 PM
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No you are wrong.

The reason you most likely have power on that wire is because it is actually a traveler from the other switch. If you were to flip the other switch then check I''m sure you'd find power on a DIFFERENT wire. The correct wire to use as the common in this case would be the wire that never registered current.

I will not argue that the common terminal is the black screw. I know this for a fact , but I will argue that it's not the black wire. This is very apparent since the light doesn't work , so unless your bulb is shot I'd feel very confident saying you wired it wrong.
 
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Old 01-26-08, 08:35 PM
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Swapping the travelers will make no difference to the operation of the switches.
I also think you have the common wire wrong.
Please tell us how you determined which wire is the common.
 
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Old 01-26-08, 08:41 PM
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Originally Posted by joed View Post
Swapping the travelers will make no difference to the operation of the switches.
I also think you have the common wire wrong.
Please tell us how you determined which wire is the common.

Pretty sure he "found" the common by checking checking for voltage. Probably just found a live traveler... I'd wager to bet that power comes into the other box and his common is actually the black from the light...
 
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Old 01-26-08, 08:46 PM
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Originally Posted by jimmyb View Post
Since the original switch worked fine and you are only replacing for a newer or prettier one, re-install old switch the way it was and see if all starts working again. if it does that lets you know you don't have any breaks in the wire or possible other problems and will allow you to start over and carefully trace you steps. Just an idea
Thanks, but I already tried that too. The old switch comes up with the same issue.

I think I'm just going to give it up and call an electrician.
 
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Old 01-26-08, 08:50 PM
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I think you should give up and try my directions.

You've all ready eliminated one wire as the common, now try the other two.

Don't forget to check the bulb !
 
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Old 01-26-08, 09:04 PM
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This is not rocket science.

There are only 9 combinations to try. Try them all and you will eventually get it right.

Pay an electrician and you will feel foolish when he or she figures it out very quickly.

Using a meter to find the common won't necessarily work. If you test the To make that test you must have the wires completely disconnected from both switches. Have any wires connected and you risk finding a traveler from the first switch that just happens to have power on it.
 
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Old 01-29-08, 04:50 PM
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Wonder how he fared out....
 
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