AS/NZS Cable Sizing
A practical column-by-column walkthrough of an AS/NZS 3008.1.1 ampacity table for first-time readers.
Like any ampacity table, AS/NZS 3008.1.1's tables look intimidating before you understand the structure. Here's the practical breakdown.
Standard mm² sizes actually available in the Australian market — not an arbitrary numeric sequence.
Copper and aluminum have genuinely different ampacity figures for the same cross-section, and insulation type (PVC vs XLPE, for instance) changes the maximum operating temperature and therefore the base ampacity — always confirm both before reading a value.
Base ampacity depends heavily on installation method — enclosed in conduit, on a cable tray, buried, or exposed in free air — each dissipating heat differently. Cross-reference the correct installation method category, not just conductor size and material.
The table's base figure is the starting point, not the final usable ampacity — temperature correction and grouping/derating factors from AS/NZS 3008.1.1's own separate tables still need to be applied afterward.
OhmWorks handles this full lookup-and-correction chain automatically in the AS/NZS Cable Sizing calculator.
Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks