GlossaryElectricalIntermediate switch
Intermediate switch
Switches Lighting · Also: 3-way intermediate, Crossover switch
In short
The middle switch when you need three or more control points for one light.
Notes
If a light must be switched from three places, you use two two-way switches plus one intermediate switch in the middle.
Rare in small flats, more useful in long corridors or multi-landing stairs.