Anybody know electricity?

[Spike Sipe]

My living room light is on a 3 way switch. Switch A stopped working, you could feel something wasnt right when you toggled it, and neither switch would turn the light on. So I replaced it. What was in there had 4 poles on it but only 3 wired up. Put a standard 3 way in, light comes on, yay?

Now, if either switch is turned on, the light is on no matter what the other switch is set to. Instead of a pair of 3 way switches, I have 2 regular switches controlling one light?!

Help?

[Paul F Franklin]

With three way switches you have two wires that are called travelers and one common. You likely swapped one of the travelers with the common. The location of the common on the switch can vary depending on brand but is either marked on the body of the switch or designated by using a different color screw (brass vs. silver usually). Unfortunately, there is no easy, reliable way to identify which wire is the common. So I suggest you identify which connection on the switch is the common connection and try connecting each of the 3 wires in turn to that connection (with the other two going to the remaining terminals), testing operation each time until switch operates properly. Remember to turn off the power each time!

[Tom M King]

See what color wire is on the common post on the original switch, and put that color wire on the common of the new switch. The common post on the new switch will have the screw head colored black. Please report back if this does, or does not work.

[John K Jordan]

What I did in a similar situation was turn off the power and use a continuity tester to map out every wire between all terminals on each switch (and the light). There are three terminals on a 3-way switch (not counting the ground terminal) and four terminals on a 4-way switch.

Multi-switch circuits are wired with a 3-way switch on either end and if more than two switches are wanted, as many 4-way switches in between as desired. There are a bunch of variations in wiring depending on where in the circuit you want to power the light - I think it is easiest to visualize the simplest case where the light is at the beginning or end of the chain, like this (images from a quick Google search):

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Here is another version of the same thing, showing the terminals on the switches:

396185

This one shows just the two 3-way switches, a logical diagram and one showing the switch terminals. (It's entertaining to read where they "let the hotness through." :))

396186 396187

If using just two switches, simply eliminate the middle (4-way) switch and connect the "traveler" wires directly from the first 3-way to the second 3-way.

If you make a table of all the connections on your wiring it will be simple (or at least possible) to make a diagram of exactly how the wires are run and then you can know for sure what to hook to what to make it work. If unsure about any of it, might be best to get an electrician to look at it.

In my situation I mentioned BOVthere were three switches, two of them 3-way and one a 4-way. Two worked as expected as long as the third one was left in one position. (It was that way when we moved into the house.) On analyzing the circuit I found that the electrician who originally wired the house had wired the center (4-way) switch incorrectly.

That was the second wiring error I found in this house. I thought maybe the guy just had a bad day. Then a few years later I met a guy who said he had wired the house. After talking to him for a few minutes I decided he was just having a bad life.

JKJ

[Charlie Velasquez]

When I purchased my last house I had several 3-ways that didn't work correctly.
I had a long piece of extra cat5 wire. Connected one end to one of the wires at one switch and ran continuity checks. Had each wire identified in 5 min.
A long spool is just handy to have around.

Edit: never mind, I see John suggested the same thing.... only in much more detail.

[Bill Dufour]

I shook hands with him when I was younger pulling the plug out of the wall for my train transformer. Quickly learned not to allow fingers beyond the end of the plastic part of the plug. So I guess you can say I know electricity.
Bill D.

[Chuck Wintle]

My living room light is on a 3 way switch. Switch A stopped working, you could feel something wasnt right when you toggled it, and neither switch would turn the light on. So I replaced it. What was in there had 4 poles on it but only 3 wired up. Put a standard 3 way in, light comes on, yay?

Now, if either switch is turned on, the light is on no matter what the other switch is set to. Instead of a pair of 3 way switches, I have 2 regular switches controlling one light?!

Help?
Don't you mean electrickery?

[Robert Engel]

Here are the checks:

The common on one switch takes power & the other common goes to the light.

The travelers go to corresponding connectors on both switches.

[Julie Moriarty]

Another way to identify the travelers

1. Open both switches and check to see which wires are hot.

2. Flip one switch and check again.

3. Go to the other switch and check again.

In the process you will be able to identify the hot wire on one switch and the switch leg on the other switch. The hot always stays hot. The switch leg is hot only when the light is on. The other two wires will alternate between hot and dead as you flip the switches. They are the travelers.