Three-Way Switches

Replacing A Three-Way Switch
To replace a three-way switch, shut off the power and remove the cover plate. Test the switch using your circuit tester to make sure the circuit is cold. Before replacing the switch, you can quickly test it for defects using a continuity tester, which will establish if the switch is indeed to blame. If your switch needs replacement, the process is easy.

Gently pull out the switch and you should see three wires inside (not counting the capped off white wires, which you will ignore). There should be one black and one red wire exiting the same hole inside the switch box (usually the bottom) and one black wire exiting a separate hole within the box (usually the top). The black wire with no red wire beside it leads to the common terminal screw. You should label this wire with a piece of electrical tape so you don’t get it confused when you replace the switch (A).

If your switch sits at the end of a circuit the wiring will be slightly different. You won’t have capped off wires and the single black wire will connect to the common terminal screw (B).

Strip the wires if they look worn. Take the switch with you to the hardware store so you can replace it with one having the same amp and voltage ratings as the old one.

Tip: If you have aluminum wiring, you should leave this job to an electrician to ensure that your home is up to code.

Attach the labeled wire to the black or copper common terminal screw of the new switch, followed by the remaining black and red wires. Gently insert the switch into the box, careful not to crimp the wires, and secure with the switch’s anchor screws. Replace the cover plate and restore power to the area.