Different Ways To Wire 3 Way Switches

There are many ways to wire 3 way switches and they work right and there are also many ways to wire them and they won’t work right. Let’s examine the most common ways to wire 3 way switches so you can see how yours may be wired or to see a few ways that  you can wire your own.

Here is a quick glossary of the terms that are used here.

1. Hot Feed- This is the romex that feeds the circuit and is hot all the time.
2. Two Conductor Romex- A romex or cable with a black, white and a bare ground wire.
3. Switch Leg- This is a two conductor romex that goes from the switch up to the light fixture.
4. 3 Conductor Romex- This is a cable that has actually 4 wires in it. A black, white, red and a bare or green ground wire.
5. 3 Way Switch- A switch that has 3 lugs for the wires plus a green screw for the ground wire to attach. Two lugs are on one side of the switch and one lug is by itself on the other side of the switch.
6. Common Lug- This is the important lug on your 3 way switch. It will be the lug on the 3 way switch that does not have another lug directly across from it on the switch. It will be on the side with two lugs.
7. Traveler Lugs- These are the two lugs on the 3 way switch that make contact with the common lug depending on which way the switch is flipped. One traveler lug will be by itself on one side of the switch and the other traveler lug will be directly across from it on the other side of the switch.
8. Common Wire- There are two common wires in a 3 way switching circuit. One common will be the constant hot feed wire and the other common will be the black wire that goes from the switch to the light fixture.
9. Traveler Wires- These are the two wires that tie the two 3 way switches together. They will be unbroken between the two switches. These could be in a two conductor cable or a 3 conductor cable and usually run directly from switch box to switch box.
10. Neutral Wire- This is the white wire that originates in the same romex with the hot feed wire that feeds the circuit hot and will go to the light fixture along with the black switch leg wire.
11. Bare Ground- This is the bare copper or green wire that should be all twisted together at each switch and light box that will tie to the green screw on the switch and the frame of the light fixture. A very important wire for safety purposes.

Here are the three most common ways that 3 way switches are wired.

• Hot Feed At One Switch And The Switch Leg At The Other Switch.

1. This is a very common method for wiring 3 way switches and it has several variations in how they can be wired. A 2 conductor hot feed comes to one switch box with usually a second 2 conductor romex as a hot feed back out of that box. Then a 3 conductor romex runs from this switch box over to the other switch box. Then a 2 conductor romex runs from the second switch box up to the light.

a.The connections in this method would be the two black wires in the hot feed in and back out romex will tie together with a pigtail wire tied in with them that will hook to the common lug on the 3 way switch.

b. The two white wires from the hot feed cables will tie to the white wire in the 3 conductor to feed the neutrals on through and send a neutral over to the other switch box where the switch leg is.

c. The black and the red wires in the 3 conductor romex are your traveler wires and will hook to the two traveler lugs on the switch. It doesn’t matter which two goes where on the traveler lugs. Just make sure that the pigtailed black hooks to the common lug on the switch.

d. The switch on the other end will have one 3 conductor and one 2 conductor romex. The black in the 2 conductor switch leg will be your common on that end and will tie to the common lug on the switch.

e. The white wires from both cables will tie together with a wirenut. That leaves the black and the red from the 3 conductor that will tie to the traveler lugs on the 3 way switch.

2. It is possible that this variation could be wired with all 2 conductor cables. If this is the case then there will be no red wires, only blacks and whites. Then it is just a matter of finding the romex that goes to the other switch box and those black and white wires will be the travelers. Everything else will wire the same.

• Hot Feed And Switch Leg At The Same Switch Box.

1. This is the simplest way to wire 3 way switches. One switch box will have three 2 conductor cables and one 3 conductor cable while the other switch box will have just the one 3 conductor cable in it.  In this variation you will need to determine two things. Which 2 conductor is the constant hot feed and which 2 conductor is the  switch leg.

This can be determined with a multimeter set on AC voltage. You will be hunting for the black constant hot feed so you will read from the black and the white in each romex until you find the hot wire. Once you find the hot wire then you will need to determine which 2 conductor is the switch leg. This can also be done with the multimeter but this time it will need to be set on the continuity reading. If there is a light bulb in the light fixture then just read the black and the white from each 2 conductor romex that you have left and the one that reads continuity will be the switch leg.

a. The connections for this variation will be the two black wires in the hot feed in and back out will tie to the black in the 3 conductor cable. They will wirenut together and push back into the switch box.

b. The white neutral wires in the two 2 conductor hot feed cables will tie to the white in the switch leg romex and they will wirenut and push in the switch box.

c. This will leave you with a red and a white from your 3 conductor cable which will be your two travelers and the black from the switch leg cable which will be your common and tie to the common lug on the 3 way switch.

d. On the other end you will have a black, a white and a red from the lone 3 conductor cable. The black is the common and hooks to the common lug on the 3 way switch and the red and white are your travelers for the switch.

• Hot Feed Pulled To The Light Fixture Box.

1. This method is another rather simple one to wire. This box will have  the two 2 conductor hot feed in and back out cables and then the two 3 conductor cables, one from each 3 way switch box.

a. The two black wires from the 2 conductor hot feed in and back out cables will tie together along with a black from one of the 3 conductor cables. It really doesn’t matter which 3 conductor you choose here.

b. The two white wires from the hot feed cables are the neutrals and they will tie together along with the white wire from your light fixture.

c. The two reds from the 3 conductor will tie together and push up into the box. The same goes for the two white wires from the 3 conductor. They will wirenut together and push into the light box.

d. This leaves you with one black wire from the other 3 conductor cable and it will tie to the black wire from your light fixture.

e. Down at the switches, the blacks will be your common and go on the common lugs on your 3 way switches and the reds and whites will tie to the traveler lugs on the 3 way switch.

It is possible that your existing 3 way switches may not be wired like the 3 examples mentioned above. The chances are pretty good though that they are wired like one of these examples anyway.

The main goal in troubleshooting 3 way switch problems is making sure which wires are the commons at your switches and getting those on the common lugs of your switch. If you do that and you have power to the circuit and your bulbs and switches are good, then the 3 ways will work like they are supposed to work.

Just remember that each 3 way switch has to have one common and two travelers to work. The two commons are the constant hot wire and the black that goes up to the light fixture.

Always turn the power off to the circuit you are working on and if you need to check for power then be sure to kill the circuit after you are through testing.