How to Install a Double Wire Light Switch

Often when you install a new light fixture, you will also need a new double wire light switch. Follow these instructions below, noting the safety tips, to install a double wire light switch.

Step 1: Shut Off the Electricity to the Switch Area

Flip the appropriate circuit breaker off or remove the correct fuse to shut down power to the switch area. The alternative is to turn off the entire breaker box with the switch handle on the outside.

Step 2: Measure Carefully and Cut Out the Wall Panel for the Light Switch

Find a wall stud to which you can attach the light switch box. Measure the light switch box and draw an opening 1/4 inch larger on all sides for it on the wall. Cut carefully with the reciprocating saw through the drywall to insert the light switch box.

Step 2: Insert the Light Switch Box into the Wall

Insert the light switch box into the wall, but do not attach it to the wall stud yet.

Step 3: Find and Attach the Double Wires to the Light Switch Box

You should see 2 wires running in parallel to each other inside the wall, a black one and a white one. Cut the black wire and connect it to the 2 brass terminal screws at the back of the switch box. Run the white wire through the switch box and attach it to the silver colored terminal screw. This wire will then continue directly to the light fixture.

Step 4: Attaching the Black Wire

When fastening the black wire to the terminal screws, turn it in the same direction as the screw threads run. If the wire is wound around the screws in the opposite direction, it will loosen as the screws are tightened. A loss of connection and an incomplete circuit will result, and the switch will not function.

Step 5: Attach the Ground Wire

Cut and strip the 2 ends of a short piece of black wire. Attach 1 end to the green terminal screw and the other to nonconducting material.

Step 6: Attach the Switch Box to the Wall Stud

Use 4 galvanized steel screws to attach the switch box at top and bottom to the wall stud. 2 screws go at the top and 2 at the bottom.

Step 7: Test the Light Switch for Correct Function

Restore the electricity to the circuit or to the whole house as needed. Flip the vertical lever on the light switch and check that the new light illuminates. If not, check all your wiring again. You may have attached the black and white wires to the incorrect terminals.

Step 8: Seal the Switch Box into the Wall With the Face Plate

Set the faceplate into the wall opening so it is snugly fitted and correctly aligned. Use the 2 brass screws to fasten it onto the light switch box to cover the switch box hole. The face plate protects the vertical switch and switch box from dust and moisture.