Instructables
video Three-Way Switches & How They Work
Three way switches are used anytime when lights are controlled by two different switches. For example  the switches  at the top  and  bottom of the stairway are both three ways.

There are many video tutorials on how to wire three way switches.  This tutorial was designed to show how the switches works instead of wiring them. This should lead to a better understanding on working with the switches and troubleshooting them.

This is the first of a series of tutorials on switches. If you like this video then you may want to take a look at  my Four-Way Switches &  How They Work.
nmoraga1 year ago
thanks , quickly learned how to use this switch :D
falecf41 year ago
Thank you! This simple explanation was awesome since I've always wondered how those switches work.