How To Wire A 3 Way Switch

There are a few things you need to know before learning how to wire a 3-way switch. A 3-way switch works differently than a single switch in one basic way. Instead of interrupting the flow of current by breaking the circuit, it simply redirects the flow of current to another circuit. When both switches are closed on the same side, the flow is open. When the switches are closed on opposing sides, the circuit is then broken, not allowing for the flow of electricity. There are three legs on a 3-way switch, and a ground, making a fourth connection. The insulated wire between the switches needs to have three conductors and a ground. From here, finding out how to wire a 3-way switch can be confusing, but when taken step by step, it is easy.

1. Before opening any wall outlet or switch, make sure the power is off to that area. On the first switch, locate the incoming power line. This will be a simple two wire line with one ground.
2. Wire nut the neutral (white) wire together with the neutral wire that exits the box to the second switch. This wire will be led to the light or outlet for a constant connection. Connect the common (black) wire from the source of power to the single black leg on the bottom of the switch body.
3. Depending on the wire being used between switches, there is ether a red wire and black wire or two black wires. At the top of the switch, connect one black wire to one silver color connector, and the other or red wire to the second silver color connector.
4. Connect both the copper wires that come into the box to the screw at the very bottom of the switch. This screw is independent of the body and is on the mounting of the switch.

The second switch will follow the same layout as the first. The wires for the first switch (the two commons) need to be connected to the silver connectors at the top of the switch. The common that goes to the light or outlet goes to the black connector at the bottom of the switch. The grounds are connected to the ground screw as in the first switch, and the neutrals are still tied together with a wire nut. This reduces your wires to the light back down to one white, black and ground.

To complete the wiring of a 3-way switch, all that is needed is to connect the last part of the circuit. Locate the white and black wire leading to the outlet or light socket. Connect the white wire to the silver side of the outlet and the black to the black side of the outlet. The ground is usually indicated by a green screw. Place all outlets and switches safely back in the wall before testing the circuit. Congratulations, you have successfully wired a 3-way switch!

Resources:

Ace Hardware