[header] How to wire a 3 way switch [title] Switch off the circuit. [step] Ensure that the circuit for the room you are working in has been flipped off. This will prevent accidental electrocution and reduce the risk of fire. 
[substeps] Most circuit breakers are located in the garage or basement, but placement will vary from home to home. When you find the breaker box, locate the breaker that controls the lights for the room you are working on.