First Class Wiring Up A 4 Way Switch
Each pair of traveler terminals should be wired to the traveler wires from one of the 3 way switches in the circuit.
Wiring up a 4 way switch. Wiring a 4 way switch is simply adding a switch to an already existing 3 way switch circuit. One ground and 4 circuit terminals divided into two matching pairs called travelers. To wire a 4 way switch start by turning off the circuit breaker for the room you re working in.
A 4 way switch must be wired between two 3 way switches as shown in the diagrams on this page. First of all we need to go over a little basic terminology on switches. When you re done with all the wiring wrap any exposed wires with electrical tape.
After that connect the black wire from the fixture to a red or white wire leading out of the box to the first 3 way switch. The travelers from one 3 way can be wired to either terminal in a pair but don t mix up the pairs on the 4 way or the circuit won t work properly. Then connect the black wire coming from the fixture to the black wire going to the first 3 way switch.
A 4 way switch has five terminals. Free quick start guide here.