As3000 Cable Selection [best] -

Measure or calculate the loop impedance using cable lengths and resistance tables (AS/NZS 3008 Table 34 or 35). If $Z_s$ is too high, you need a larger cable or a different breaker type.

Clause 3 of AS/NZS 3000 dictates how the cable is installed.

AS3000 Cable Selection Guide | PDF | Electrical Impedance - Scribd