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3 Switch Calamity


JollyGreen55's Avatar
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05-18-17, 08:24 PM   #1 (permalink)  
3 Switch Calamity

I went to put a dimmer on a setup with three switches. Assuming it was normal setup, I bought a 3way dimmer and was going to install on one of the ends.

To my surprise I have the following configuration:
First Switch: 3 way switch with one 3 wire and one 2 wire, neutrals connected
Second Switch: 4 way switch with two 2 wires (???) All connected to switch.
Third Switch: 3 way switch with a single 3 wire, all connected to switch

I disconnected​ all the wires from the switches and placed wire nuts on them. Turned the power on and investigated which wires are hot.

First Switch: black from 2 wire was hot, black and red from 3 wire are travelers
Second Switch: both wires from one pair is hot and both from second pair is not
Third Switch: all three are hot.

Any ideas what could be going on here?

 
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05-18-17, 09:27 PM   #2 (permalink)  
Welcome to the forums.

Just to clarify....
switch 1 - 1) two wire cable and 1)three wire cable.
switch 2 - 2) three wire cables.
switch 3 - 1) three wire cable.

Is that correct ?


~ Pete ~

 
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05-18-17, 09:30 PM   #3 (permalink)  
Nope ....
switch 1 - 1) two wire cable and 1)three wire cable.
switch 2 - 2) two wire cables.
switch 3 - 1) three wire cable.

 
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05-18-17, 09:41 PM   #4 (permalink)  
Interesting and going to be hard to troubleshoot.

With a four way circuit..... the wiring goes from one 3w switch to the 4w switch and then to a three way switch. The three ways are always at the end.

If you have red and blacks as travelers..... how/where do they convert to the two wire cables that show up at the 4w switch ?

If the black of the two wire cable at switch 1 tests as hot.... there should be no other hot wires found anywhere in the wiring. Testing for hot wires should be done with a meter or voltage tester..... not a non-contact pen.


~ Pete ~

 
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05-18-17, 09:57 PM   #5 (permalink)  
I should clarify I am assuming the red and black on switch 1 are travelers (based on the third avaiable being hot). You're correct that I determined hot wires using a non-contact pen. I will use the meter and post the results in a bit.

 
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05-18-17, 10:37 PM   #6 (permalink)  
Switch 1 - Single black from two wire connected to either red/black from three wire returns 100V, red to black from three wire returns no voltage

Switch 2 - black to white on the hot pair (according to non-contact tester) no voltage, Black to Black returns 40V White to White returns 40V, I didn't cross test these but can if it would be helpful.

Switch 3 - White to black or red 40V, black and red together returns no voltage.

I

 
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05-19-17, 06:28 AM   #7 (permalink)  
deleted ...........................

 
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05-19-17, 08:30 AM   #8 (permalink)  
Re post #6: Usually readings at switch boxes don't help much. The voltages below 100 may be due to using a digital multimeter instead of an analog multimeter. They'd probably be ~0 on an analog multimeter. The 100 volt may be feeding through a load. Only useful information would be if you found a 2-conductor cable that when disconnected read ~120v black to white. Then we would know where your power in likely was.

Tell ust the wiring at the light. That may help.


I can explain it to you, but I can't understand it for you.

 
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05-19-17, 10:08 AM   #9 (permalink)  
The mystery is how they converted from 3w cables at the three way switches to 2w cables at the 4w switch.

I'm sorry to say, as far as I see, the circuit isn't a mystery. That two wire cable coming into switch one is a switch loop. If you were to connect the white and black the lights would probably come on. That would confirm the switch loop.

If that is the case.... there is no neutral at the 1st switch which means you won't be able to use a dimmer on that switch system.


~ Pete ~

 
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05-19-17, 01:50 PM   #10 (permalink)  
Oye! Not what I was hoping to hear but thanks for the feedback.

 
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