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Adding a 4 way switch to my existing two 3 way switches for main lighting

IONH

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Feb 12, 2010
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2,043
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Central Massachusetts
Okay, so my first attempt at adding another switch to my existing two 3 way switch setup failed because I bought another 3 way switch and didn't understand exactly how the circuit worked. That caused me to do some research and found the following link.

4WayAnimation.gif

http://users.wfu.edu/matthews/misc/switches/4WayAnimation.html

Alright, let me start with the 3 way wiring is existing. I did extend it months ago to add some T8 fixtures with conduit, but I did not touch the switch wiring.

I figured the switch at the back wall is the one which is really responsible for supplying voltage to the main lighting. I am adding a switch by the front side door, this is the 4 way. The front wall at the center of the doors has the other 3 way.

Long story short, after a couple of hours of troubleshooting, I figured out that the rear 14-3 line was providing power on the red and white wires, depending on switch orientation. Okay, so the black must be common. This 3 way is very old and has no ground screw (that tells its age right there). Let it be noted that this rear 3 way has two 14-2 romex hooked up to it and I do not know where in the ceiling it turns into 14-3 to get to the front wall, probably near the original lights back there.

I think I set up the 3 way in the front with the red as common (darker screw) and white and black on the other screws.

I hooked the 4 way up with two runs of 14-2 romex. I attached both whites to one side of the switch and both blacks to the other side.

I got both 3 ways to work with the 4 way in one position but not in the other.

I'd like to say "thankfully" I haven't popped any circuits because this is all dealing with hot wires so the only two "wrongs" are lights ON or OFF at any time and no popping circuits. This said, I can experiment with wire orientations till it finally all works... this is definitely a challenge of my legs and knees crouching in the attic swapping wires to then go back downstairs to turn the breaker on and try the switches in my heavily cluttered garage. I must be down to the last couple of combinations by now!
 
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OccupantRJ

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Eastern North Carolina
Make sure you have a 4 way switch and not a double pole switch. The double pole should have the handle marked for on/off, while the four way will not. The wires you are trying to connect into are called the travelers.
 

TheMightyPetrie

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Apr 12, 2013
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....leave the "hot" in exactly as it is (black screw on THAT 3-way). leave the switch leg out exactly as it is (black screw on THAT 3-way)...
the 4-way switch intercepts the travelers from both 3-way switches.....
both travelers from switch 1 to one side of the 4-way, both travelers from switch 2 to the other side of the 4-way....
 
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OccupantRJ

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Make sure you hook up the wires from one END of the switch to the other END of the 4 way. If you are hooking up to pass through the switch SIDEWAYS, this might be your issue.
 
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I

IONH

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Feb 12, 2010
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Central Massachusetts
....leave the "hot" in exactly as it is (black screw on THAT 3-way). leave the switch leg out exactly as it is (black screw on THAT 3-way)...
the 4-way switch intercepts the travelers from both 3-way switches.....
both travelers from switch 1 to one side of the 4-way, both travelers from switch 2 to the other side of the 4-way....

That's exactly how I read it. The tough part is figuring out which traveler wire is which from each of the 3 way switches. I know which is which from my 4 way.
 

Milton Shaw

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Feb 11, 2011
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4,840
To hook up the 4 way remove the two travelers from one switch, connect one new 14/2 to those traveler terminals and then attach the two wires you took off to the other new 14/2 to the 4 way. That should fix the connection problem. You also need to check how the 3 way switches are designed, some I have seen the travelers are on one end of the switch another design has the two travelers on the side of the switch. This causes a lot of connection problems when replacing three way switches. Check the 4 way for the came connection problem side or end for a pair of travelers.
 
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IONH

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Feb 12, 2010
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Central Massachusetts
Finally figured it out!

I had assumed the switch was connected in one position ACROSS the switch when it is actually top to bottom.

Thinking about it, that's the same way a regular 1 way light switch is connected so I should have known.

Thanks everyone for trying. I got it set up successfully in about 90 more minutes of wasted time tonight.
 
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