In this video scott gives you a step by step instructional tour of how to wire and install a pair of 4 way switches in your wood shop. To replace a four way switch follow these steps.

How To Replace A 2 Gang Switch
How to replace a 4 way switch. Fully explained 4 way switch diagrams. 4 way switches are a convenient way to operate lighting fixtures from three or more locations. A 3 way switch is a spdt single pole double throw and only connects to 1 traveler wire. The electrical wiring adds additional wiring to the same principles of 3 way switching. These 3 way occupancy sensor switches may replace the existing 3 way switches. You cant just swap the switch without also replacing some wiring.
Unscrew and remove the switch plate. The sensing pattern should be adjusted as wide as possible and the time delay should be adjusted to provide enough time to travel the full distance of the stairway. It is important to understand how these switches are wired before attempting to troubleshoot or replace. 4 way switch configurations are used to control lights with three or more switchesa 3 way switch is used on each end with one or more 4 way switches in between the two 3 way switchesthey do not have an onoff position like single pole switches. Unscrew the switch from the electrical box and pull it out with the wires still. He will also explain how a 3 way circuit works.
Most 4 way switch wiring is placed between the wiring of two 3 way switches. Install a 4 way occupancy sensor to replace the existing 4 way switch. Turn off the power to the switch at the circuit panel or fuse box. 4 way switch wiring. Then use a voltage tester to make sure that the circuit is dead.