The Australasian approach: a hard 5% cap from the point of supply to any point of the installation (AS/NZS 3000), with cable data tabulated in AS/NZS 3008.1 as three-phase mV/A/m — and the famous trap that single-phase circuits must multiply the tabulated value by 1.155 — handled automatically below.
The cap covers the whole path, so designers allocate it across stages — a common pattern is roughly 1.5% consumer mains, 1.5% submains, 2% final subcircuits, but any split that sums within 5% complies. Model a real chain stage-by-stage with the multi-segment calculator.
| Cable | Ω/km (per cond.) | 3Ø mV/A/m | Rating A |
|---|---|---|---|
| 1.5 mm² | 15.000 | 26.0 | 20 |
| 2.5 mm² | 9.000 | 15.6 | 27 |
| 4 mm² | 5.625 | 9.7 | 37 |
| 6 mm² | 3.750 | 6.5 | 47 |
| 10 mm² | 2.250 | 3.9 | 64 |
| 16 mm² | 1.406 | 2.4 | 85 |
| 25 mm² | 0.900 | 1.6 | 112 |
| 35 mm² | 0.643 | 1.1 | 138 |
The tabulated three-phase value equals √3 × ρ/A × 1000; multiply by 1.155 (2/√3) for single-phase — this calculator handles that automatically via the system selector. Full context on the Australia/NZ calculator page.
No — AS/NZS 3000 makes it a requirement of the Wiring Rules, checked at inspection. The NEC's equivalent figures are informational notes unless adopted elsewhere.
Convention: most distribution design is three-phase, so 3008.1 tabulates the line-to-line figure and lets single-phase designers apply the 1.155 factor.