Wow, just realized, I do not have a anything on wire sizes. I know what my next project will be.
The thing about wiring is there are variables i.e. is the wire copper or aluminum, wire length, number of conductors in conduit etc etc. It could be AWG 4, 6, or 8 depending on.....
Whatever I provide will probably be applicable to NEC regulations which should pretty much be same as Canada and European for the most part. What you need to do is find out what regulations are followed in your country and obtain the wiring tables.