If you're asking about UK three prong plugs - the earth cable is green and yellow, the live is brown and the negative is blue.
3core*400mm2 xlpe cable
Mostly for small dc motor, 2core are used. earthing can be achieved by grounding the chassis.
in case of motor, only 3core cable are used. Because there is phase balence between the winding. But in case of wiring,panel installation, 3.5c cables are normally used. Because there is unbalenced between the phase current. So the neutral taken to give the return path to flow of unbalenced (rush) current. Which always less than phase current,so the neutral cable is take half of the phase cable.
the current rating of a 70mm swa 3core cable is 1.2 amps buried or 2 amps on perforated cable tray suspended 500 feet above sea level in antartica