Four-Way Switch

A four-way switch has two sets of traveler wires running between it and a pair of threeway switches. There is no common wire nor is there a common terminal. The continuity test for a four-way switch requires a few extra steps. You need to put the clip on any pair of traveler screw terminals separately and then touch each of the other screws with the probe. This is a total of six tests for each position of the toggle (see the following figures). The test should show two continuous currents for each position of the toggle switch. (The paths between specific traveler screw terminals vary with different manufacturers.)

A four-way switch box has two cables with three conductors coming into it (thus four hot conductors or wires). Two are black; the other two are a second color, most likely red. When you replace the switch, be sure to match the wires to the correct traveler terminals. New four-way switches either match their terminals up by color (two are brass and two are copper), or the back of the switch might have wiring instructions. This makes your job easier. You simply have to match one color of wire insulation to one set of screws (red wires to brass screws, for example). See the following figures for a typical installation.