On/on vs On/(on)

[iampoor]

Whats the difference between an On - (On) switch and an On - On switch? Or an On - Off and On - (off) switch?

I feel like a dumbo for not understanding this!

[David_AVD]

on-off - single throw (2 terminals per pole)
on-on = double throw (3 terminals per pole)
on-off-on = double throw (3 terminals per pole) but with a centre position where neither side is connected

[Psi]

i cant think of any reason for the brackets around the 2nd on.
So both of those are probably exactly the same.

Edit: Unless the brackets are some really weird way to imply an inverted contact (NO vs NC) etc, but i've never seen it written like that before

[Andy Watson]

on-off - single throw (2 terminals per pole)
on-on = double throw (3 terminals per pole)
on-off-on = double throw (3 terminals per pole) but with a centre position where neither side is connected

Agreed. I would guess that the brackets indicate the switch is biased, i.e. spring loaded for momentary action.

[Psi]

oh, true.

Yeah, momentary would make sense for the bracket meaning
Can't believe i didnt think of that.

[Monkeh]

Brackets indeed indicate a momentary position.

[MLXXXp]

on-off - single throw (2 terminals per pole)
on-on = double throw (3 terminals per pole)
on-off-on = double throw (3 terminals per pole) but with a centre position where neither side is connected

I've also seen on-on switches, without a centre off, specified as on-none-on.

[fcb]

As Andy Watson said.  The brackets indicate that is spring loaded.

e.g. (on)-off-(on) would indicate centre off bias.