Question

the size of a conductor used in power cables depends on the

Answer 1

The size of conductor used in power cables depends on the current that needs to be carried.

Current is the rate of charge flow from positive point to negative point. It is symbolized by the uppercase or capital letter I and its standard unit is ampere represented by A. Electric current are of two types- 

Direct Current (DC) and alternating current (AC).

Answer 2

It depends on the current that is carried by it.
it's standard unit is Ampere represented as A