Proper wiring for 3-way switches?

Old 10-01-22, 11:57 AM
Thread Starter
Join Date: Aug 2007
Location: USA
Posts: 50
Likes: 0
Received 0 Likes on 0 Posts
Proper wiring for 3-way switches?

I have 3 switches along a hallway, let's call them A B and C.

If A is off, then flipping C does nothing (B works).
​​​​​​If C is off, then flipping A does nothing (B works).
​If A and C are both off, then flipping B does nothing.

Is this expected? If not, which receptacle(s) need to be fixed?

To be clear, the behavior I'd want is, flipping any switch inverts the current state of the light.
Old 10-01-22, 12:11 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,951
Received 3,169 Likes on 2,846 Posts
That's a four way system. Two three way switches and one four way switch.
It's almost impossible to diagnose based on which switch operates when.

If you can pull each switch out and post a picture of the attached wiring...
we can help you locate the problem.... How to insert pictures.

This is a diagram of one way to wire that circuit. Your color locations could be completely different.

Old 10-01-22, 01:29 PM
Join Date: Sep 2015
Location: US
Posts: 995
Received 120 Likes on 104 Posts
Before pulling the switches, turn the breaker for the lights off.

If the correct switces are in place, one switch has failed OR they are miswired. If any of the 3 switches has ON/OFF markings, it's the wrong switch. If any of the switches are backstabbed (conductor poked in a hole in the back of the switch instead fo connected to screw terminals), one of the backstabs may have failed; they're notorious for failing.

You should have two 3-way switches (3 terminals each) and one 4-way switch (4 terminals). Each of the 3-ways will have 1 screw thatís a different color;l. On one 3-way the odd color screw is connected to the an hot conductor (black?) and on the other 3-way, the odd color screw is connected to a conductor going to the light(s).

Forget the 4-way for a few minutes. The other screws on the 3-ways are connected to conductors called travelers, 2 conductors running between the 3-ways. It doesn't matter which traveler connects to which screw on the 3-ways.

The 3-way with the always hot, switches power from one traveler to the other. The other 3-way switches the light(s) from one traveler to the other.

Now for the 4-way. It sits between the 3-ways and connects the travelers; hopefully you will have something like Red & Black for your travelers. Different brands use different terminal arrangements. Some 4-ways use different color screws; dark and brass for the travelers from one switch and the other dark and brass for the travelers from the other switch. If the travelers are Red and Black, connect the Reds to one color screws and Black to the other color screws. You can use a meter to find the arrangement on a 4-way, but it's a pain. If I have another 4-way handy, I just replace.

Even with the breaker off, it's a good idea to check all conductors at each box for power. don't assume everything is powered down. There may be spliced conductors in the boxes, leave them alone unless absolutely necessary.

Keep us posted!
Old 10-01-22, 03:28 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,951
Received 3,169 Likes on 2,846 Posts
@ ThisOldMan.... I'm not easily confused but that is confusing.
We need to see his wiring.
Old 10-02-22, 03:58 AM
Join Date: Mar 2014
Posts: 842
Received 109 Likes on 91 Posts
BryGX - also what ever you do don't remove the wires from the switches when you pull them out to take pictures, that will just complicate things. Take clear pictures.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: