I am upgading the electricity supply to our factory. (through City Power) According to my electrician, a 125mm cable is needed, 800amp breaker at the sub and 600 amp breaker at our main board. Now, City Power tells me that a 75mm cable is sufficient. A little internet reading says 213 amps for 75mm cable, is this per phase of the total amps? If for the cable then it's too small...

Any advice would be much appreciated as this is way above my pay grade. I don't want to be in a position of paying for the upgrade and power being supplied is not enough.