Four-Way Switches

Add a crossover switch between two 3-ways to control one light from three locations.

What you’re building

Steps

1. Build the 3-way circuit first

   Wire the two 3-ways and the light exactly as in the three-way guide, but don’t finalize the travelers — you’ll break into them.

2. Insert the 4-way into the travelers

   Place a 4-Way Switch in the middle of the two traveler wires, between the 3-ways. Its two inputs come from switch A’s travelers; its two outputs go to switch B’s travelers.

   3-Way A T1 → 4-Way in 1

   3-Way A T2 → 4-Way in 2

   4-Way out 1 → 3-Way B T1

   4-Way out 2 → 3-Way B T2

3. Energize and test all three

   Click Energize. Flip the 4-way (middle) — light toggles. Flip either 3-way — light toggles. All three locations now control the one light. Add more 4-ways for more locations.