How to Wire a Photocell Switch

G.K. Bayne

Photocell switches are typically used on outdoor lighting. This allows the power source for the light to remain on at all times. The photocell switch will then turn the light on at a predetermined time, generally dusk, and off when the sun rises.

Power must always be applied to the photocell switch for the light activation portion of the switch to operate properly. Wiring a photocell into a light circuit can be accomplished in a short period of time and will save you money on your monthly utility bill.


Follow all local electrical regulations whenever servicing any electrical devices. Use only outdoor-rated switches for exterior applications.

  1. Remove all electrical power from the outdoor light fixture you are placing the photocell on to control. Pull the light bulb from the light fixture.

  2. Use the screwdriver and pull the light fixture from the electrical box. Remove the two wire nuts from the black and white wires that are connected to the light fixture and power source. Place the fixture on a flat surface so you can install the photocell.

  3. Knock out the ½-inch-diameter connector hole. This is typically located on the front of most outdoor light fixtures. Place the metal tip of the screwdriver on the round knockout hole. Strike the large end of the screwdriver with the wire pliers. The metal knockout cover should pop out.

  4. Insert the metal threaded end of the photocell through the hole you just made. Tighten the switch into place by threading the small lock nut from the backside of the light fixture. Tighten the nut with the jaws of the wire pliers.

  5. Observe that there are three wires coming from the photocell switch. The white wire is the switch's neutral wire and the black is the main power going into the photocell switch. The red wire is the “switch” wire coming from the photocell.

  6. Connect the wires in the following order. Use the wire pliers and twist together all three of the white neutral wires, covering the bare copper ends with a wire nut. Connect the black wire of the photocell switch to the black wire, the power source, that is coming from the electrical box the fixture attaches to for mounting. Twist the two wires together and cover with a wire nut. The last two wires to connect will be the red wire from the photocell to the black wire of the light fixture itself. Again twist the pair of wires together and cover with a wire nut.

  7. Attach the light fixture to the electrical box. Replace the light bulb. Reenergize the power to the fixture. Adjust the metal band in front of the photocell for the correct amount of light to enter the switch for activation. You may have to wait until dusk to adjust the metal band properly.