Wire a two-way switch wrong and the light doesn't fail loudly, it just refuses to turn off from one end of the landing, which is somehow worse.

What Is Two-Way Switching and When Do You Need It?

Two-way switching is what lets you turn a landing light on at the bottom of the stairs and off at the top, or control a hallway light from either end. It uses two 2-way switches, not a standard one-way switch at each end, connected by a 3-core-and-earth cable carrying the two strapping wires (commonly called L1 and L2) between them.

It's also the standard setup for long hallways, garages with a second door, and bedrooms where you want a switch by the door and another by the bed.

Two-Way vs Intermediate: What's the Difference?

A 2-way switch has three terminals and works in pairs, one at each end of the run. The moment you need a third control point, the two end switches stay as 2-way switches, and you add an intermediate switch, which has four terminals, in the middle of the cable run. You can chain in as many intermediate switches as you need between the two 2-way ends.

Why Won't My Light Turn Off From the Other Switch?

This is almost always L1 and L2 swapped on one of the two switches during wiring or a rewire. The light still works, both switches still turn it on and off, but the logic gets inverted so one switch only works when the other is in a specific position. It's one of the most common callbacks on a landing light job, and the fix is checking the strapping wire terminals against the wiring diagram on the back of the switch plate, not replacing the switch itself.

Two-Way vs Intermediate: Quick Comparison

Which BG Evolve Switch Plate Should You Spec?

For a standard landing job, two 2-way switches are all you need. The intermediate only earns its place once a client wants a third switch somewhere awkward, like a long hallway with a door partway down. If you're also speccing dimmers on the same job, our trailing edge vs leading edge dimmer guide covers picking the right module, and the full BG Evolve range keeps every plate on the job in a matching finish.

Frequently Asked Questions