Wiring Diagram: 3-Way Switch

This is a typical diagram of how to connect 2 switches to the same light. It’s especially handy for stairs, hallways, and big rooms.

You will notice that the power feed goes into one switch box, while the switch leg (light wire) goes into the other.  There is also a “traveler” line that connects the two together.

Traveler:
The traveler is a 3 wire Romex cable with a ground.  In other words, there are 3 insulated wires and an uninsulated ground wire.
The ground wire is for added safety and all grounds should be tied together to maintain the safety path.
The white wire is the neutral wire which is the circuit return path for the light.  It also goes to ground, and all white wires should be tied together to maintain the circuit path.
The red and black wires are the travelers that hook the two switches together.  These are attached to the 2 top terminals (or bottom – depending on how you’re holding it).  It doesn’t really matter which one goes where on those 2 terminals.

Wiring Diagram: 3-Way Switch (alternate)

This is an alternate way to wire 2 switches to the same light.  Sometimes it’s more convenient to put both the power feed and the switch leg in the same switch box.