Install a Three Way Switch to Control a Light
Installing a three-way switch adds the convenience and control of turning a stairway light on or off from either the top or bottom of the staircase. A three-way switch doesn't have an on or off indicator so installing two switches to the light will open or close the circuit, which in turn controls the power. You need a three wire plus ground cable, in addition to a two wire plus ground cable, to properly complete the project.
Instructions
1. Turn the power off, at the main service panel, that controls the light switch and light that will be converted to a three-way switch.
2. Loosen and remove the screws on the existing light light switch cover, and set the cover aside. Remove the screws, using the screwdriver, that are holding the light switch in its box. Pull the switch out of the box, and remove the wiring. Let the wiring hang free, and discard the switch.
3. Locate an area to install the second switch. Measure up from the floor about 4 feet, and mark the wall. Cut a hole, using the saw, in the wall at the mark, just large enough for the new junction box to fit into. Punch out a knockout hole in the back of the box, using the screwdriver, and slide the junction box into the wall. Using the included screws, tighten them down to secure the box in place.
4. Drill a 1/2 hole (from the attic) in the top plate of the wall over the two locations where the wall switches are located. The wiring for the light is already in the attic and accessible, so no drilling will be needed to access the light.
5. Feed one end of the 12-3 ROMEX® cable down through the hole in the top of the wall and out the junction box at the new switches location. Feed the other end of the 12-3 cable in the same manner down to and out the junction box of the existing switch. Feed the 12-2 ROMEX® cable down through the wall to the new switch and route the other end over to the wiring for the light, which is in the attic.
6. Cut each cable so that 6 inches are extending out each junction box and at the light. Strip 3 inches of the outer sheathing, and 1 inch of insulation of each wire, at each end of the cables run in step four.
7. Connect one new switch at the original junction box location. Attach the existing wiring from the service panel and the new wiring to the switch in the following pattern. Group the white wires and green/bare wires together by color and twist the ends together, and then twist a wire nut on the end of the two connections. Attach the black wire from the service panel to the labeled "com" screw on the switch and tighten it down. Attach the black wire from the three-wire cable to the labeled "traveler" screw on the left (facing the switch) and the red wire from the three wire cable to the "traveler" screw on the right.
8. Attach the wiring from the light and the three-wire cable to the remaining switch. Group the white wires and green/bare wires together by color and twist the ends together, and then twist a wire nut on the end of the two connections. Attach the black wire from the three wire cable to the labeled "traveler" screw on the left (facing the switch) and the red wire from the three wire cable to the "traveler" screw on the right. Attach the black wire from the light to the labeled "com" screw. Tighten the screws down.
9. Attach the light to its wiring. Attach the black wire to the brass screw, the white wire to the silver screw, and the green/bare wire to the green screw. Tighten the screws down.
10. Attach each switch to its box, using the included screws to tighten them down, and install a cover plate over each switch and tighten its screw down.
11. Turn the power back on at the service panel, and test each switch for power and operation of the light.
Tags: wire from, Attach black, Attach black wire, black wire, black wire from, service panel, three wire