Journeyman Electrician

Three-Way & Four-Way Switching

How current actually flows through a pair of 3-way switches (and an optional 4-way in between) to control one light from multiple locations.

NEC 404

POWER hot 3-WAY #1 common travelers traveler A traveler B (shown open) 4-WAY (optional -- adds a 3rd location) 3-WAY #2 common 💡 LOAD The light is ON when the same traveler carries current all the way through. Each 3-way switch connects its common terminal to ONE traveler at a time -- flipping either switch changes which traveler completes the path. A 4-way switch just passes travelers straight through, or crosses them.
All mindmaps