Dumb question maybe...

Fan switch: ON - OFF

Poles on back: 1 - 2 - 3

If all we want is ON and OFF, what is the third pole for?

I have managed to figure out wiring all my instruments, and now I'm onto switches.

Third pole is for the Normally closed/normally open function'

So the three contacts will be;

Common

Normally closed

Normally open

Get a multimeter and check it out but that will be the functions.

Might be helpful

http://www.kpsec.freeuk.com/components/switch.htm

wot Jag says.

you need to think inside the box, the switch box.

inside is a spring loaded wiper that moves on a pivot.

As show in the picture, contact is made between 2 and 3 - this is n.c.

you push the toggle down, contact is made between 1 and 2 now - this is n.o.
Rescued attachment swt.JPG

unless the switch is illuminated single pole.
third connection could be for this.

George

That's it. Tx