AS/NZS Cable Sizing Commercial
Three-phase sizing under AS/NZS follows familiar logic with its own specific current formula and neutral considerations.
Three-phase cable sizing under AS/NZS 3008.1.1 follows the same structural logic covered in the PEC three-phase article — ampacity and voltage drop checked independently, using the √3 current formula — but pulled from AS/NZS's own independently derived reference tables.
Three-phase current (A) = Power (W) / (√3 × Voltage × Power Factor)
Base ampacity figures, grouping derating factors, and voltage drop resistance/reactance data all come from AS/NZS 3008.1.1's own tables — not transferable from PEC or NEC results for the same nominal load and length, even though the underlying physics and process structure are identical.
As with any code, a three-phase commercial installation with significant harmonic-generating equipment (variable-frequency drives, electronic ballasts, switch-mode power supplies) may require a neutral conductor sized equal to or larger than the phase conductors, rather than assumed negligible under a purely balanced-load assumption.
Run your three-phase commercial load through the AS/NZS Cable Sizing calculator.
Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks