Project Guide

How to Wire a 3-Way Switch

1
TURN THE POWER OFF AT THE BREAKER BOX
A person using a voltage tester on an light switch
  • Turn off the power for the circuit at the breaker box. Test with a voltage tester to confirm. If the tester shows current, check the service panel and turn off another circuit that powers the switch. Test again and proceed only if the tester shows no current. 
  • Remove the wall plate.
2
REMOVE OLD SWITCH AND INSPECT WIRES
A person using a screwdriver to remove mounting screws from an light switch
  • Remove mounting screws and gently pull the switch out of the wall box. 
  • Inspect the wiring. A loose or broken wire could explain why the switch doesn’t work. 
  • Disconnect the wires. If the wires are stabbed into the back of the switch, insert a small flat head into the slot above the wire to release. If you are having problems, simply cut the wire. 
  • When disconnecting the wires, mark the wire on the black or dark colored screw as common. Mark the wires on the brass or light colored screws as travelers. Make notes or take a picture to verify connections before removing the old switch.
3
PREPARE WIRES FOR CONNECTING TO THE NEW SWITCH
 A person using pliers to bend copper wires into a hook inside of an light switch
  • Remove insulation so ¾-inch of copper conductor is showing. 
  • Use long nose pliers to bend the end of each wire into a hook. Make sure the hook is tight enough to fit around the terminal screw.
4
CONNECT WIRES TO THE NEW SWITCH
A person attaching hooked copper wires around terminal screws of light switch
  • When wiring a 3-way switch, first screw the terminal screws of the new switch until they are difficult to turn. 
  • 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. 
  • Connect the wires to screw terminals by slipping the looped wire under the head of the screw. The end of the loop should point clockwise. 
  • Use long nose pliers to squeeze the wire end tight around the screw. 
  • Tighten the terminal screws.
5
WRAP THE BODY OF THE SWITCH WITH ELECTRICAL TAPE
A person covering all terminals and bare wire of light switch with electrical tape

Cover all terminals and bare wire with electrical tape for added safety.

6
PLACE NEW SWITCH IN THE WALL BOX AND COVER WITH WALL PLATE
A person installing a new light switch in the wall
  • After wiring a switch, insert the switch in the wall box.
  • Tighten wall plate screws with flat head screwdriver.