Installing a three-way switch means putting in a second electrical switch, and wiring it to an existing electrical switch. This project requires two new three-way switches, wire strippers, and a small screwdriver. It can be done completely in a little under two hours if wall framing is open, but may take much longer if the wall is closed in. It should be noted that installing a three-way switch requires basic electrical skills, and should not be performed by someone unfamiliar with wiring. In that case, a licensed electrician should be called to perform the work.
A three-way switch is a single power source that can be controlled by two different switches. These types of switches can be most often seen controlling the lighting along hallways, or on stairways. It is also be useful in rooms with multiple entrances or exits. This helps a person avoid having to walk all the way to the opposite end of the hallway to flip a switch. Instead, the person can use the closest of two switches.
When working with any type of electricity, there are certain safety precautions that should always be taken. Be sure to turn off the power and test the wires to ensure that the power is off. To avoid someone turning the power back on while the work is still being done, lock out the panel box.
Before any work can be done, a wire path plan must be made to where the second switch should be located. If possible, keep the second switch location the same height as the first switch’s location. Remove the cover plate, exposing the actual switch, and then the existing electrical box. If necessary, replace that electrical box with one designed to accommodate the additional wires and connectors needed for a three-way switch. It may be necessary to enlarge the wall opening for the new box.
The next step is to cut a hole where the second switch will be located. Run the wiring from the first electrical box to the second electrical box, making sure to leave at least three inches of excess wiring at each box. Then, tighten the screws at the top and bottom of the box to clamp it into place.
Now, it is time to wire each of the electrical switches. Strip each wire about three quarters of inch from the end, and connect those wires according to the wiring diagram that came with the new three-way switches. Fit the switches tightly into the boxes, and fold any wiring into the box before screwing the switches in place. Next, reinstall the cover plates and turn the power back on. The three way switch installation is complete.
Uncoordinated switches are a common problem when installing a three way switch. Ideally, both switches will be in the same position when the light is turned off. If that’s not the case, remove one of the switches. Rotate the box 180 degrees, so that switch positions are coordinated and re-attach the switch. The problem should be solved.