On Mon, 26 Dec 2016 18:49:10 -0600, Mark Lloyd
wrote:

On 12/26/2016 11:54 AM, James Wilkinson Sword wrote:

[snip]

Called 3-way in the US. I think I understand why, but 2-way sounds more
reasonable.

It can be 3-way (or more) if you want, you add a switch in the middle
that swaps the poles. But if there's two switches, calling it 3-way is
illogical.

IIRC, what I heard is that its called 3-way because there's wiring going
to 3 places (each switch, and the light). It does sound strange. I'd
like to use 3-way for THREE switches.

[snip]

That is just an old electrician tradition. When you have the cross
connected DPDT switch, used as an intermediate switch in a pair of
travelers it is a "4 way" even though it functions exactly the same.
It just has 4 ungrounded conductors.