How to Wire Three-Way Switches to Two Lights
Current National Electrical code requires a light switch at each entrance to a room or hallway so persons entering the room won't have to cross the room in the dark to turn on a light. The light switches may control a receptacle for a lamp or light fixtures for permanently installed lighting. Three-way switches allow people to turn lights on or off from different locations, regardless of the position of the other switch.
Turn off power to the circuit you are working on by switching off the circuit breaker.
Install sheathed cable between the first three-way switch and the second three-way switch. Make the cable long enough to protrude from each wiring box 8 to 10 inches. Strip 8-inches of sheathing from the cable at each end with the cable stripper and insert the wires into the wiring boxes until about 1/2 inch of sheathing enters the box.
Install sheathed cable from the second switch to the first light fixture, then from the first light fixture to the second light fixture, and from the second light fixture to the first switch. Strip 8 inches of sheathing from each end of each cable and insert the wires into the wiring boxes. Place a piece of black electrical tape on the two cable ends that enter the switch boxes to temporarily mark them.
Cut a piece of sheathed cable 8-inches long. Pull the bare ground wire from the cable. Hold it together with the two ground wires in the first switch box and twist the ends together with the lineman's pliers. Screw a wire nut over the connection. Bend the free end into a "U" with the long-nose pliers, place it clockwise around the green terminal on the three-way switch and tighten the screw firmly. Repeat this for the other switch.
Strip 3/4 inches of insulation from the existing white house wire and the white wire marked with the electrical tape in the first switch box. Twist the bare ends together with a lineman's pliers. Place a wire nut over the twisted wire ends and screw it clockwise until it is tight.
Strip 5/8 inches of insulation from the existing black house wire in the first switch box. Bend the wire end into a "U" with the long-nose pliers and place it clockwise around the gold terminal. Tighten the terminal firmly. Place a wire nut over the end of the black wire that runs to the second light fixture. This wire is not used.
Strip 5/8 inches of insulation from the black and white wires that run between the switches. Turn the bare ends into a "U" with the long nose pliers. Wrap the insulation on the white wire end with black electrical tape to recode them black. Place the wire ends around the black terminal screws on both switches and tighten the screws firmly.
Place a wire nut over the end of the white wire in the second switch box. This wire is not used. Strip the end of the remaining black wire, turn it into a "U" and place it on the gold terminal. Tighten the terminal firmly.
Strip 3/4 inches of insulation from all four wires in the first light fixture. Twist the ends of the bare wires together, then the white wires, then the black wires. Connect the bare fixture ground wire to the bare cable ground wires with a wire nut. Repeat this for the white fixture wire to the white cable wires, and the black fixture wires to the black cable wires.
Strip 3/4 inches of insulation from the two white wires in the second fixture box, and 5/8 inches from the black wire coming from the first fixture. Twist the bare cable ground wires together and connect them to the bare fixture wire with a wire nut. Twist the two white cable wires together and connect them together with the white fixture wire. Connect the black wire from the first fixture to the black fixture wire. Place a wire nut over the end of the remaining black cable wire.
Things You Will Need
- Sheathed cable with two wires plus ground
- Electrical tape
- Cable stripper
- Lineman's pliers
- Wire nuts
- Long-nose pliers
- Light fixtures
- Three-way switches
- The fixture wires are stranded wires. Connect the stranded wires to the solid cable wires without twisting the wires together. The wire nut will do that for you. Solid wires connect together by first twisting them together, then adding a wire nut.
- The two black terminals on the switches are called travelers. One of the two terminals is always "hot" and the switch position determines whether the light is on or off. Recoding the white traveler wire black with tape or a black marker lets the next person know the wire may be live."
- Be sure to turn the power off before you start work.