Three-way switches are commonly used to control a light fixture from two different locations. For example, a long hallway or stairway might use a pair of three-way switches at each end so that lights can be turned on when approaching one end of the hall or stairway, then shut off from the other end.

Do both switches need to be 3 way?

No, you can use each switch for a different 3-way circuit. ... No, it isn't necessary to replace both switches as long as the position you're installing it in has access to the neutral.

What is the difference between a 3 way switch and a regular switch?

The most common household switch, a single-pole, has two terminals and simply turns power on or off. A three-way switch has three terminals; a four-way has four. ... You can usually replace any single-pole switch with a dimmer.