3 Way Switch Wiring Diagrams

On this page are several options for wiring 3 way switches to control a light. Wiring diagrams include different configurations depending on the location of the electrical source in relationship to the switches and the light. Also included are diagrams for a 3 way dimmer and an arrangement to control a receptacle outlet from two locations. Find more information about these circuits and troubleshooting tips below.

Wiring Notes:The source neutral in these circuits will always be connected to the neutral terminal on the light. If the source is at the light, connect it directly to the fixture, otherwise, splice the neutral wire at each switch box so it is passed to the light fixture box. The ground wire should be spliced with a pigtail and connected to each device that has a built–in grounding terminal and to any grounding terminal on the outlet boxes.

When wiring these circuits the white wire is sometimes used to carry electricity between devices, when this becomes necessary wrap the end of the wire with electrical tape to mark it as hot. These drawings illustrate 15 amp circuits using 14/3 cable between the switches and 14/2 cable to the light fixtures. Existing household wiring used for lighting and receptacles may be on 15 or 20 amps circuits. To use this wiring in 20 amp circuits use 12 awg cable and devices rated at 20 amps.

3 Way Switch Circuit, Source at the Light

In this diagram the source for the circuit is at the light fixture and the two switches come after. 14/2 cable runs from the light, to the first switch and 14/3 runs from there, to the second switch. The hot source is spliced to the white cable-wire, running it through to the common terminal on the second 3–way switch. The hot terminal on the light fixture is connected to the black, 14/2 cable-wire and then to the common terminal on the first 3–way switch. The red and black wires on the 14/3 cable connect the traveler terminals between the two switches.

3 Way Wiring, Source and Light Together

In this drawing the source for the circuit is at the light fixture and the two switches are on opposite sides. 14/3 cable runs from each switch to the light. The hot source is spliced to the white cable-wire on one of the 14/3 cables and then run to the common terminal on one of the switches. The hot terminal on the light fixture connects to the white on the second 14/3 cable and to the common terminal on the other 3–way switch. The black and red cable wires are spliced at the fixture box and connected to the traveler terminals on both switches.

3 Way Circuit, Source at First Switch

Here the electrical source is at the first switch and the light is located at the end of the circuit. 14/3 cable runs between the switches and 14/2 runs to the light. The 14/3, black and red wires are connected to the traveler terminals on each switch. The hot source is connected to the common terminal on the first switch and the common terminal on the second switch connects to the black, 14/2 cable-wire which runs to the hot terminal on the light.

3 Way Circuit, Light in the Center

The source in this circuit is at the first switch and the light fixture is located between the 3–way switches. 14/3 cable runs between each switch and the light fixture. The hot source wire is connected to the common terminal on the first switch. The common terminal on the second switch is connected to the white cable-wire and then run to the hot terminal on the light. The black and red wires are spliced at the fixture box to run between the traveler terminals on the switches.

3 Way Dimmer Wiring

This diagram shows the wiring for a specially made dimmer that can be used in these circuits in place of either of the the 3–way switches. This arrangement allows for lowering the lights. After the dimmer level has been set the other switch will turn the lights off and on at that level. This device can be used in place of any of the 3–way switches in these diagrams, as well as to dim the lights in a 4 way circuit.

Instead of terminals, a 3-way dimmer has 4 wires coming out of the casing: one common, two travelers and one ground wire. The common wire is usually black and the travelers red. In any case, the traveler wires will usually be the same color to distinguish them from the common wire.

The source in this circuit is at the light and the switches come after. 14/2 cable runs from the light to the 3–way switch and 14/3 runs from there, to the dimmer. The hot source is spliced at each box to run through to the common wire on the dimmer. The hot terminal on the light fixture is connected to the black cable-wire and then to the common on the 3–way switch. The traveler wires on the dimmer are spliced to the 14/3 black and red wires, which are then connected to the traveler terminals on the 3 way switch.

Controlling a Receptacle from Two Locations

This diagram shows the wiring to control a receptacle outlet from two locations. The source is at the first switch and 14/3 cable runs between all the devices. The hot wire from the source connects to the common terminal on the first switch. The common on the second switch is connected to the white cable-wire, which becomes hot, and then to the hot terminal on the receptacle. The black and red cable wires are spliced in the receptacle box to run to the traveler terminals on each switch.

Why Use a 3 Way Switch

Three way switches allow for controlling a light fixture from two locations. These are usually used at the top and bottom of a flight of stairs or at two different entrances to a room. Another option for controlling a light fixture from three or more locations, is with the use of a 4 way switch, wired between two, 3 way switches. Several 4 way switch wiring diagrams can be found at this link and see wiring multiple lights in 3-way circuits at this link.

Modern three way switches have 3 terminals to carry circuit electricity and one terminal for a ground wire. Older devices will not have a ground terminal. Of the three circuit terminals, one is called the common and the other two are known as travelers. The common terminal may be labeled and is usually a different color than the traveler terminals. Depending on the manufacturer, the travelers may be on opposite sides of the switch or the two terminals may be on the same side. In any case, the common terminal will be distinguished from the travelers in some way.

The common switch terminals will always be connected to a hot wire, either the hot source or the hot on the light fixture. These connections can be reversed if it's more convenient, as long as one of the 3 way common terminals connects to the hot source and the other one connects to the hot on the load, these circuits will work properly. The traveler terminals will always be connected from switch to switch. Travelers never connect to a device load or to a source wire. It doesn't matter which traveler terminal is used for which traveler wire, reversing them should make no difference.

Troubleshooting 3 Way Circuits

All the diagrams on this page have been tested in real life circuits but because of variable factors in existing wiring, the examples displayed here may not work in every instance. To avoid problems make sure the hot wire from the source is connect to the common terminal on one of the switches and the hot wire to the fixture is connected to the common on the other. Likewise, be sure the traveler terminals are connected between switches, only. If after checking this wiring, you still experience problems with the circuit, reversing the traveler wires may resolve the problem.