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On and Off Switch Symbol, Which is Which?

The humble on/off switch. Not something I had pondered much until someone asked me what meant what on the switch. Was the 0 off or was the line off? I had no clue, so decided to have a look into it myself.

The symbols on an on/off switch are actually supposed to be a 1 and a 0. The numbers are supposed to be binary 1 for on 0 for off.

on off switch
on-off switch

This system was adopted rather than just using the words on or off to try and make it more universal. Obviously on and off don’t mean much if you don’t speak English.

A really easy way to remember which is which is to just remember that the o is a 0. 0 = nothing, so no power. This is the way I will remember it from now on, I always find that trying to remember the reason why helps me remember things easier.

Another good reason for this system rather than text is that it is easily readable no matter the orientation. This is not the same with text, which as soon as it is not the right way up gets a lot harder to understand.

This is really useful for these switches which can end up anywhere. Upside down, on their sides, they tend to end up in all kinds of orientations which makes it great that you can understand it quickly no matter which way it is facing.