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# Need help with 3-way switches

## Need help with 3-way switches

#1
04-12-04, 08:25 PM
dp2
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Need help with 3-way switches

OK, after painting, I replaced 2 3-way switches, which control 1 light.

switch #1 has 2 black and 1 red wire
switch #2 has 1 black, 1 white, and 1 red wire

None of the different wiring combinations have worked properly. (I checked the wiring of 2 other 3-way switches I replaced, each one had 2 black/1 red.)

Any ideas?

#2
04-12-04, 08:41 PM
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Is that a complete inventory of all the wires in the box? Just three wires in the box (ignoring grounding wires)? No more tucked into the back of the box that were not connected to the switch?

If there is any additional information available, it would be useful.

#3
04-12-04, 08:47 PM
dp2
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The box for switch #1 has 2 white wires capped off.

Right now if switch #1 is up, switch #2 can turn the light on or off. But when switch #1 is down, switch #2 does nothing.

#4
04-12-04, 09:09 PM
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Okay, that helps.

If all else fails, there are three choices of which wire to attach to the common (black) screw in box #1, and three choices in box #2. That's 9 combinations. You could solve this by trial and error only, and it would never take more than 9 tries. Statistically, it should only take four or five. The exercise walking back and forth to the panel is good for you.

But we might be able to save some trips by applying a bit of common sense.

Start at box #1. The presense of the white wires in box #1 says that this is where the power comes in. Identify the two cables. One is a black/white cable, and one is a black/red/white cable. Attach the black from the black/white cable to the black screw. Attach the other black and red to the other two screws in either order (but not to the green screw!!). This is almost certainly correct for box #1.

Box #2 is the end of a switch loop, and is a bit harder to tell for sure. But the answer is probably to connect the black wire to the black screw, and the red and white to the other two screws. This will probably work.

#5
04-12-04, 09:37 PM
dp2
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Alright, after making white common in box #2, the switches worked.

Thanks for the help. Now I'm off to tackle a few more switches.