How to Wire a 4-way Circuit

 
A four way or 4-way switch circuit is used any time you are using three or more switches to control a single light or device.  A 4-way circuit will always contain two (2) 3-way switches and at least one (1) 4-way switch.  If more switches are to added they would be 4-way switches and added to the center of the circuit.  You should have a good understanding of how a 3-way switch and circuit works, before attempting to wire a 4-way circuit.

What is a 4-way switch?

A 4-way switch has four terminals (2 inputs and 2 outputs) and sometimes a green ground terminal.  The switch either connects the inputs to the outputs directly across from it, or it will connect the inputs to the outputs diagonally across from it.  It will NOT have ON and OFF stamped on the switch.  Do not confuse this switch with a 2 pole switch which also has four terminals but has the ON and OFF labels.  The four way switch is either going to be connecting the screw terminals horizontally across from each orher and diagonally cross connect when switched or it is a different type of switch and will connect the screw terminals vertically across from each other and diagonally cross connect when switched.  Read the diagram that comes with the switch, look at the markings on the back of the switch or use a meter to see whidh configuration the switch is.  The following diagram shows the two positions of both types of 4-way switches. 

Wiring the 4-way circuit

The basic configuration of a 4-way circuit starts with a power source entering into the common of the first 3-way switch, the travelers from the first 3-way switch (feed 3-way switch) connecting to the two input terminals on the 4-way switch.  The second set of travelers start at the 4-way switch output terminals and are then connected to the second 3-way switch (load 3-way switch).  The common of the second (load) 3-way switch is the connected to the light.  The neutral wire is just to be passed through all the way to the light and should not be connected to any switches.  The ground should also be passed all of the way through to the light, but should also be connected to any ground terminals on the switches.  Click below on the 4-way switch wiring diagram for an enlarged drawing.

Wiring Diagram for a 4way switch

Adding more switches to the circuit

If more switches are to be added to the circuit, 4-way switches should be added after the existing 4-way switch.  Travelers from the first 4-way switch outputs should be connected to the second 4-way switch inputs.  The outputs for second 4-way switch should be connected to the travelers going to the second (load) 3-way switch, or to the inputs on next 4-way switch (if even more are switches are to be used). 

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