4 way switch wiring comes in real handy when you would like to control a light fixture from more than two locations.
While wiring a 3 way switch is good enough for a staircase or hallway, wiring a four way switch is crucial for the addition of a third, forth or more switches.
Why would you need more than two light switches? Well, there a a number of reasons. Perhaps you have a large room with more than two exits and you want to wire a light switch at each doorway. Or maybe you want to turn the garage light on from the front door, the back door and the side door. Wherever you think another switch would come in handy, learning how to wire in that third or fourth light switch is actually quite easy once you have mastered the three way switch.
The first thing people get confused with is actually buying the proper light switch. There are many types of switches; single pole, dual pole, 3 way, 4 way...
Four way switches look very similar to dual pole switches but they work very different. A dual pole switch is used primarily to turn one 240V circuit on and off, much the same as a single pole switch is used to turn one 120V circuit on and off.
A four way switch allows the traveller wire from one switch to travel through or criss-cross between another switch.
Enough about that! Lets start wiring a four way switch.
In order for 4 way switches to work, they must be installed between two 3 way switches by 14/3 wire. There are really only two basic four way switch wiring methods...
In this scenario you will have a 14/2 wire coming from the light fixture into a three way switch. A 14/3 wire is then used to go to a four way switch. Another 14/3 wire is used to connect another three way switch where the circuit will end.
Here you will have a 14/2 wire coming from the power source into a three way switch. A 14/3 wire is then used to go to a four way switch. Another 14/3 wire is used to connect another three way switch and finally a 14/2 wire is used to connect to the light or multiple light fixtures.