How are three-way wall switches work? Is there a 3-way switch for? What is a three way light switch? The three-way switch is a variation of the standard single-pole switch , which controls a light only from one location.

A third type is the four- way switch , which is used in conjunction with two three-way switches to control lighting from more than two locations. Figure A: 3- Way Switch Wire Diagram — Power to Light Fixture. This 3- way light switch wiring diagram shows how to do the light switch wiring and the light when the power is coming to the light fixture. In this diagram, power enters the fixture box.
The next most common is the three-way switch , which is 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. An intermediate switch can, however, be implemented by adding appropriate external wiring to an ordinary (six terminal) DPDT switch , or by using a separate DPDT relay. By connecting one or more 4- way (intermediate) switches in-line, with 3- way switches at either en the load can be controlled from three or more locations.

If you have ever wondered how this arrangement works and how each switch knows what the other switch is doing, then read on.


