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replacing 3 way switches

1K views 9 replies 5 participants last post by  Jim Port 
#1 ·
I have 2 three way switches I am replacing in one electrical box that each control a different light. My problem is trying to figure out where the wires hook up.
I have 4 yellow wires, one red and one orange and two whites nutted together in the box.
Any ideas on what to put where. I've tried all kinds of combinations- I can now get each light to turn on and off at is box I am working at, but each light will not work at the other switch location.
 
#6 · (Edited)
can you walk me through the steps I would need to do to get the correct wires hooked up ?

Thanks
It'll take me a while to write up this procedure. It's extremely tedious but, in return, you get certainty as to where each wire goes. In general, you make a guess as to where each wire goes and then test to confirm/disprove.

Of course, with just an ohmmeter and using an extension cord as a test lead, with power off and an assistant, you can open up the other two boxes and check continuity between all boxes. This will confirm most or all of the wire destinations to some level of certainty [depending on the switch positions, and assuming a wire has not been spliced and so has a different color at each end].

Also, if your neighbor's house is just like yours, you can copy what he has.

In any case, do not disconnect any more wires.
 
#4 ·
Do you know if any of the wires is unswitched (constant hot)? You can figure this out with a non-contact voltage detector. (about $10 at HD/Lowes).

Spread all the wires out so they are not touching (but the ones that were nutted together before you started...leave them alone). Then turn the breaker on and use the meter to see if any of them are hot regardless of the positions of the other switches. Make sure nobody touches the exposed wiring when you are not near them!!!
 
#5 ·
Assumption Alert:

I would start with the red and orange on the common terminals. You will also need to figure out the grouping of the yellow travelers.
 
#7 ·
Assume the existing switches work. DON'T TOUCH ANY WIRES EXCEPT THE THREE THAT ARE ON THE SWITCH. Look at the old switch. One of the terminals should be black or a different colour from the rest. That is the common terminal. Look for the black on the new switch and connect the common wire to it. Ther other two wires don't matter. Change one switch at a time and verify operation before changing the second switch.

If you can't identify the common wire then it will only take three tries to find it since the other two wires don't matter to the operation of the switch.
 
#8 ·
replacing three way switches

Thanks for the info-- I do have the red and orange wires wired to the common points on the switch- but I am baffled as to how to place the four yellow wires. I know 2 need to go to each switch- but I have tried all kinds of combinations and can't get it right.
Any advice on how to proceed with these 4 wires ?
 
#9 · (Edited)
Any advice on how to proceed with these 4 wires ?
Switch off any breaker even remotely likely to power this setup.

With your double wide box labelled as #1 and the other two boxes labelled as #2 and #3 and the four yellow wires in box #1 labelled as A, B, C & D,
run your ohmmeter with its extension cord from a yellow wire in box #2 to each of the four unconnected yellow wire ends in box #1. But first put your meter on the 240vac scale and check for 'zero' voltage; you never know.

Repeat for box #3.

4 +3 +2 + 1 = 10 tests in all.

If you can't get 'zero' voltage turn off your main breaker and try again.
In principle an AC voltage should not affect an ohmmeter that uses DC current to test the resistance, but the real world is not quite so predictable.




I've never put my test procedure in writing because it's in my head and some of it may depend on instinct.

Since you might have this fixed by now without this procedure, I'll post it in chunks as the need arises. Here are the cases covered so far for an unidentified wire of indeterminate color coming out of a resi. box:

Distant Wire End [E] has on it. . .
120v w/respect to ground [E1] or
ground [E2] or
open [E3] or
other?

Wire Middle [M] has in it. . .
splice, good or bad, with different color on each side or not [M1], or
lamp [M2] or
switch [M3] or
other?

Any other real-life cases are certainly welcome.



Maybe this will turn lurkers into members.
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"
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The "90-9-1" version of this rule states that 1% of people create content, 9% edit or modify that content, and 90% view the content without contributing.
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#10 ·
There would only be 2 combinations using the yellow wires. Either you get it right or you would switch one wire and get it on the second try.

Did you check the other switch to see what colors the travelers were?
 
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