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3 way wiring

Posted by casiocarcharger (My Page) on
Sun, Feb 17, 13 at 18:45

Hi!
I have 2 three-way wire switches operating a single light bulb. I recently replaced both switches with three-way Decora switches and now the switches no longer operate properly.

I understand how three-way switches work (from internet research) and I can't figure out why my switches aren't working.

From a purely mathematical perspective, there are a total of 36 possible permutations of how my two switches can be wired. I've attempted to draw this in my picture below:

1. Each box represents a possible connection scenario.

2. The first line in each box represents one three-way switch
R=Red
B=Blue
O=Orange

3. The second line in each box represents the other three-way switch

4. The third line in each box represents the result of the connection.

"1" =
> light can be turned on/off by lower switch if upper switch is off
> light can be turned on/off by upper switch if lower switch is off
> light can NOT be turned on/off by lower switch if upper switch is on
> light can NOT be turned on/off by upper switch if lower switch is on

"2" = light is on regardless of switch on/off position

So far, I've only had time to test out 7 of the possible 36 permutations. (actually, I believe I've gone through all permutations once before, but didn't record them one-by-one on paper)

Admittedly this brute force approach is probably funny to those of you with electrical expertise. I am just looking to save some money before hiring an electrician so please help with some real advice (better yet, a solution) instead of typical internet junk posts.

THANKS FOR ANY HELP!

p.s. I suspect there is an additional issue in play here. The house has a security system. When I shut off the main switch, the house has a weird high-pitched noise (not sure where it originates from). Turning the three-way switch on/off affects this noise.


Follow-Up Postings:

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RE: 3 way wiring

I need to clarify "#4"

4. The third line in each box represents the result of the connection.

"1" =
> light can be turned on/off by lower switch if upper switch is off
> light can be turned on/off by upper switch if lower switch is off
> light can NOT be turned OFF by lower switch if upper switch is on (light remains ON)
> light can NOT be turned OFF by upper switch if lower switch is on (light remains ON)


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RE: 3 way wiring

If you use logic you don't need to calculate a bunch of random hook-ups by a blind guy.

Look at this pic. Take note of the black screws on each switch (common terminals).

If you wire it up and it's not working as planned, in the distant box (leading to light fixture) switch the two wires on the silver terminals.

Here is a link that might be useful: diagram

This post was edited by homebound on Sun, Feb 17, 13 at 21:05


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RE: 3 way wiring

Each three way switch has a common terminal. You have the wrong wire on the common terminal.
If you can trace the wires the always hot wire at one switch and the switched hot going to the light are the ones that need to be on the common screws.

I have no idea what your chart is showing, but somehow the two settings where the light can not be turned off should identify the hot and light wires.


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