Three Way Light Switch Question

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  #1  
Old 05-19-11, 01:43 PM
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Three Way Light Switch Question

Looking for some guidance, please. I am replacing two three way dimmer switches with two three way regular light switches. It should be easy enough, at least by process of elimination of the common wires vs. the travelers, but I'm having some difficulty. It seems as if one switch will turn the light off, the other will not turn it on and vice-versa. Here's what I've done so far:

- I've identified the hot wire on the switch coming from the light fixture and wired that to the common screw (the screw is black in color and indicates the word "common" on the back of the light switch).
- I've wired the other two travelers to the remaining to brass colored screws. This is where I'm stuck.

In the other switch, there is a black, red, and white wire. I've tried identifying the common wire by testing the resistance of each. It's my understanding that only one should show resistance but I have two that are showing resistance. I swear I've tried every possible combination without luck.

Any advice would be greatly appreciated! Thank you!
 
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Old 05-19-11, 02:07 PM
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The travelers should be the same color as they were in box #1. The remaining wire should be the common.
 
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Old 05-19-11, 02:31 PM
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Thanks for your response, ibpooks. I'm not sure that's entirely possible in this case. I have a white and black wire coming into switch #1. The black (hot) wire is connected to the common terminal and the white one is connected with a wire nut to another white wire (presumably running from switch #2 and its white wire). So, in switch #1, that leaves a red and black wire for the travelers. In switch #2, I have the black wire connected to the common terminal (like in switch #1) and the red and white ones connected as the travelers. It sounds like you're saying, though, that the white wire in switch #2 should be connected to the common terminal and the remaining black and red wires should be to the travelers, right? I think I've already tried this without success.
 
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Old 05-19-11, 03:31 PM
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Lets stop talking wires and start talking cables. Do you have a 2-conductor cable (+/g) and a 3-conductor cable (+/g) at one switch and just a 3-conductor cable (+/g) at the other switch or just a 3-conductor cable (+/g) at each switch or something different? Describe the cables at the light.

You really seem to be making this harder then it should be. The dimmers would have had 3 wires. Two the same color the third a different color. The house wire connected to that different color goes to the common on the new switch. The house wires to the two like colors on the dimmers to the traveler screws of the new switch.. No other wires should have been touched.
 
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Old 05-19-11, 04:29 PM
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"Lets stop talking wires and start talking cables. Do you have a 2-conductor cable (+/g) and a 3-conductor cable (+/g) at one switch and just a 3-conductor cable (+/g) at the other switch or just a 3-conductor cable (+/g) at each switch or something different? Describe the cables at the light."

What you describe above is what I have. Unfortunately, both dimmers have been disconnected so I can't obviously now tell what was connected to what. I'm sure that the 2-conductor cable (+/g) and a 3-conductor cable (+/g) at one switch are all connected properly. It's the switch where just the 3-conductor cable (+/g) at the other switch is what I'm not sure about. If I'm understanding correctly (?), the traveler wires on each switch should be the same colors, right?
 
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Old 05-19-11, 04:58 PM
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the traveler wires on each switch should be the same colors, right?
The screws yes. The wires to the screws, maybe. There is no standard color just what most people do.

The two conductor is probably a switch loop. You can verify that by looking at the light.

Assuming it is a switch loop here is how to connect it up.

At the switch with a 2-conductor and 3-conductor cable:

2-cond. white to 3-conductor white.
2-cond. black to common.
3-cond, red and black to switch travelers.

At the 3-conductor cable only switch:
White to common
Black and red to the switch travelers.

Note the white of the three conductor cable between the switches should be recolored blue or some other color except green or gray.
 
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Old 05-19-11, 05:39 PM
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Not exactly sure what a switch loop is, but you set me straight with your explanation about how to hook it up. I couldn't understand how the white at the 3 conductor only cable could be the common. I always thought it was either the black or the red wires. Thanks for your help!
 
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Old 05-19-11, 06:44 PM
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Not exactly sure what a switch loop is
Below is a basic switch loop. The power comes in at the light, down one side of the switch loop and back up the other.
In the case of this 3-way it goes through the the 3-cond. white to the second switch common then back to the first switch through one of the travelers to the first switch common and then back to the light.
 
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