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Discussion Starter · #1 ·
I have a light that is supposed to be controlled by two 3-way switches. Someone has replaced one of the 3-ways with a single pole. I want to wire back correct with a 3-way. How do I determine which wires go to which poles on the new switch?
 

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That just doesn't sound to safe:smile:

I do have a tester.
You already know that the two wires on the SP switch are connected, so there should be a 3rd wire sitting in the box,

the worst that can happen is the light won't turn off, or turn on or it will work.

What color wires are in the box and on the other end?
 

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Discussion Starter · #5 ·
You already know that the two wires on the SP switch are connected, so there should be a 3rd wire sitting in the box,

the worst that can happen is the light won't turn off, or turn on or it will work.

What color wires are in the box and on the other end?
So the 3rd wire in the box. Would that be the "traveler" or "common"?
 

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The third unused wire would be one of the travellers. That means it will only take two tries to get the proper wire on the common.
Is the other three way switch still connected and functioning?
 

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Put the unused traveller wire on one of the traveller screws. Put the two wires from the old switch on the other two screws.
Test the switches and see it functions properly. If not then switch the two wires from the old switch. Test it again.
 

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That just doesn't sound to safe:smile:

I do have a tester.
since you have a tester, this should work. check the 2 wires that are on the single pole switch. when the switch is off (light out) one wire will have power. that wire goes on the common screw (usually dark colored) of the 3 way. the other 2 are the travelers.

edit, I can see a condition where this may not be the case.
 

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That only works if the power comes into the switch in question. If power comes into the other switch then that is not true.
Just hook it up and try it. It can not cause a problem if the other switch is wired properly.
 

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You will not trip the circuit.

Just try the 3 wires in different combinations on the 3 terminals of the new switch. If it's not correct, working with a partner at the other switch, turning on and off in random turns will determine the correct wire locations when the switch functions properly.
 
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