How to Install a Timer Switch With Three Wires & Two in Outlet Box

A timer switch lets you control lighting in a room by programming the switch to turn on and off at selected times. The timer switch connects the same way to the household electrical wiring as a standard toggle switch. The third wire on the switch is for grounding the circuit to the outlet box in the wall. As with any electrical wiring project, follow all the outlined safety precautions to prevent injury or death.

Screwdriver set
Wire strippers
Wire twist-on connectors

Instructions

- 1
  Turn off the power to the room at the circuit breaker or fuse box. For safety, test the existing wall switch or a nearby outlet to confirm the power is off.
- 2
  Remove the two screws holding the faceplate to the existing switch on the wall.
- 3
  Take out the screws holding the old switch at the top and bottom to pull the switch out of the outlet box.
- 4
  Loosen the screws in the side of the old switch to remove the two wires attached below the screw heads.
- 5
  Strip 1/4 inch of insulation from the end of each wire on the back of the timer switch.
- 6
  Connect the black wire on the timer switch to the black wire in the outlet box. Twist the bare wires together and then screw on a connector cap.
- 7
  Fasten the white wire on the timer switch to the white wire from the outlet box and secure with a screw-on connector.
- 8
  Wrap the remaining wire on the timer switch around a screw in the outlet box and tighten the screw.
- 9
  Secure the switch in the outlet box with a screw in the bracket hole at the top and bottom.
- 10
  Replace the original cover plate over the metal spindle on the front of the timer switch, or use a plate supplied with the new switch.
- 11
  Line up the knob supplied with the new switch with the metal spindle and push on the knob.
- 12
  Turn on the electricity at the circuit breaker or fuse box.

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