How to Wire a 3-Way Switch

Before you start your 3-way switch wiring project, it’s good idea to have a basic understanding of electrical wiring. Take a moment to identify the hot and neutral wires and review the color-coding system for different types of wires.

Wiring a new 3-way switch is a project you can do yourself with the right tools and a little time. Here are the tools and materials you’ll need:

• Screwdriver
• Wire cutters
• Needle-nose pliers
• Voltage tester
• Electrical tape

Tip: If you’re not comfortable working with electrical wires and switches, consider hiring an electrician.

The first step learning how to wire a 3-way switch, or doing any electrical project, is to turn off all power to the current switch. Make sure you identify the right switch in your breaker box for the room or area you are working with.

Safety Tip: Consider wearing goggles and insulated gloves when working with electricity.

• Unscrew the wall plate and remove it.
• Use a non-contact voltage tester to test each wire before proceeding.
• If you find a live wire, try turning off another circuit in your breaker box.
• Test for current again before proceeding.
• Remove the mounting screws.
• Gently pull the switch out of the wall box and inspect the wiring. A loose or broken wire could explain why the switch doesn’t work.
• Snap a photo of the original wiring to verify connections in Step 5.

Next, disconnect the wires. There are two possible ways to do this:

• For wires connected with screws, use a screwdriver to loosen the screws and remove the wires.
• For wires pushed into the back of the switch, insert a small flat head screwdriver into the slot above the wire to release it. Or simply cut the wire.
  Once you’ve disconnected the wires:
• Label or mark the wire on the black or dark colored screw as common.
• Label or mark the wires on the brass or light-colored screws as travelers.

Make sure to properly strip the wire insulation and secure the wires under the appropriate terminals. There are two ways to connect to the new switch when wiring a 3-way switch.

If the device has a slot in back and a pressure connector:

• Strip the wire insulation 3/4 inch.
• Loop the bare end of each wire clockwise around the appropriate screw terminal on the switch.
• Use long nose pliers to squeeze the wire end tight around the screw.
• Tighten the terminal screws with a screwdriver.

If there are two slots in back:

• Strip the wire insulation 3/4 inch from each wire.
• Use long nose pliers to bend the end of each wire into a hook.
• Tighten the hook to fit around the terminal screw.
• Screw the terminal screws until they are difficult to turn.

For either type of device listed above, refer to the photo you took in step 3 or:

• Connect the ground wire to the green screw.
• Connect the wire marked common to the black or dark colored screw.
• Connect the two remaining traveler wires to the two brass or light-colored screws.

After wiring your new three-way switch, insert it carefully back into the wall box.

• Screw the wall plate back on with a flat head screwdriver.
• Turn the power back on at the breaker box.
• Turn on your new 3-way switch.