[TeMPOraL]

Then there's standard walls switch in Europe, which works whichever way the electrician happened to wire it. And then, existence of "stair switches"[0] means you can't ever rely on directionality being consistent.

Now, let's talk about water faucets and which side is hot, and which one is cold...

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[0] - Don't know what the formal way for these are; I'm thinking of two switches hooked up in a XOR pattern to the same light - i.e. light turns on when the switches are in opposite positions, and off if they're in the same position.

[JohnFen]

> Don't know what the formal way for these are

These are called "three-way switches" in the US.

[SoftTalker]

Oddly named, as they only have two switches in the circuit.

[JohnFen]

They're called "three-way" because there are three elements to the circuits they're used in: two switches and a load.

...or so I was taught, but that explanation always seemed a little dubious to me.

[cyberge99]

I thought three-way was for three possible states: up/down, down/up, or down/down(up/up). Switch 1 up, switch 2 down, etc.