What's an intermediate switch?

In article , DIYdisaster writes

Same as crossover switch identified here:

Do you know how to wire a pair of 2 way switches (say) at the top and bottom of the stairs?

You can put an intermediate half way up so the lights can be controlled from all three switches. You simply break the strapping wires and connect them to the four terminals on the switch operating the switch simply reverses the connections of the strappers making the "on" condition "off" and vice versa.

It's used when you want 3 or more switches to be able independently to switch a single light (or group of lights wired in parallel).

Two-way switching is straightforward, but if you want 3 or more ways you need to insert one or more intermediate switches between the 2-way jobbies. An intermediate switch simply swaps the two through connections and thus toggles the light on and off.

OK now I get it. Thanks for your replies.

Damn cleaver these electrical chaps.

Sharp as a blade...

The confusion arises because two-point switching uses two-way switches. Three (and more) point switching uses two two-way switches and one (or more) intermediate/crossover switches.

-- JGH

Buggit, that was me. Previous owner left himself logged in.

-- JGH

Two way plus intermediate switching circuit.

L1 L1 0===========0 0===========0============= Line | \ / | C 0================================O C \ / \ / 0===========0 0===========0============= Switch return L2 Optional L2 Intermediate

FMAAYOR (follow my advice at your own risk) IINAE (work it out for yourself)

Also useful as a reversing switch for a dc motor etc.