If you need the actual tables or a worked example for a specific scenario (e.g., 50 mm² XLPE buried in clay, 30 m run, 3 circuits), let me know.
This standard is the de facto bible for cable sizing in Australia and New Zealand. Unlike the US NEC (which uses tables with fixed ampacities) or the UK’s BS 7671, AS/NZS 3008 uses a that accounts for a wide range of environmental and installation variables. 1. The Core Philosophy: The "Derating Factor" Model AS/NZS 3008 does not give you a single number like "2.5 mm² cable = 20 A". Instead, it gives a current-carrying capacity (CCC) base value, then forces you to multiply by a series of coefficients. as/nzs 3008
$$I_z \ge \fracI_nC_d$$