Cable Sizing Calculator per AS/NZS 3008.1.1:2017 for New Zealand
Cable sizing in New Zealand follows AS/NZS 3008.1.1:2017, the same joint standard used in Australia. Engineers select conductors using Table 3 current-carrying capacities, apply New Zealand-specific ambient temperature derating from Table 22 (typically more favourable than Australia due to cooler climate), and verify voltage drop within AS/NZS 3000:2018 5% limits.
Quick Reference Table
| New Zealand Cable Sizing Key References — AS/NZS 3008 — AS/NZS 3008.1.1:2017 (2017) | ||
|---|---|---|
| Parameter | Value / Requirement | Clause Reference |
| Supply voltage | 230 V single-phase / 400 V three-phase | AS/NZS 3000:2018, Clause 1.4.4 |
| Frequency | 50 Hz | AS/NZS 3000:2018, Clause 1.4.4 |
| Current-carrying capacity | V-75 (PVC) and X-90 (XLPE) per Table 3 | AS/NZS 3008.1.1, Table 3 |
| Voltage drop limit | 5% from point of supply to any outlet | AS/NZS 3000:2018, Clause 3.6.2 |
| NZ ambient temperature reference | 25-30 °C typical (cooler than Australia) | AS/NZS 3008.1.1, Table 22 |
| Regulatory body | WorkSafe NZ (administers Electricity Act 1992) | NZ Electricity Act 1992 |
| Common conductor sizes | 1.0, 1.5, 2.5, 4, 6, 10, 16, 25 mm² | AS/NZS 3008.1.1, Table 3 |
| Earthing system | TN-C-S (MEN system) predominant throughout NZ | AS/NZS 3000:2018, Clause 5.1 |
How to Calculate Cable Sizing for New Zealand
- 1
Calculate NZ circuit demand
Determine design current per AS/NZS 3000 Part 2 maximum demand rules. Apply Table C1 diversity for domestic installations. NZ domestic mains typically rated 63 A single-phase.
- 2
Choose cable type and installation method
Select cable insulation (V-75 TPS or X-90 XLPE) and installation method from Table 3. NZ domestic installations predominantly use flat TPS cable clipped to timber framing.
- 3
Apply NZ derating factors
Apply ambient temperature correction from Table 22. NZ's temperate climate (typically 20-30 °C) generally requires less derating than Australian conditions. Apply grouping factors from Table 24 if circuits are bundled.
- 4
Select conductor size from Table 3
Choose the minimum conductor size with a derated current rating that meets or exceeds the design current. Cross-reference with minimum sizes per AS/NZS 3000 Table 3.2.
- 5
Check voltage drop for NZ conditions
Verify total voltage drop from mains to final outlet is within 5% (11.5 V at 230 V). NZ rural properties can have long consumer mains runs — allocate voltage drop budget between mains and sub-circuits.
Try the Cable Sizing Calculator
Run compliant AS/NZS 3008.1.1:2017 calculations for new zealand — free, instant results with full clause references.
Calculate Cable Sizing NowBS 7671 vs AS/NZS 3008 Cable Sizing Comparison
| Parameter | BS 7671 | AS/NZS 3008 |
|---|---|---|
| Region | United Kingdom | Australia & New Zealand |
| Voltage drop limit | 3% lighting / 5% other | 5% general (AS/NZS 3000 Table C7) |
| Reference ambient temp | 30°C air | 40°C air (Table 22) |
| Ampacity tables | Appendix 4 Tables 4D1A–4J4A | Tables 13–20 (by method) |
| Derating tables | Ca, Cg, Ci, Cc factors | Tables 22, 24, 25, 26 factors |
| Soil temp reference | 20°C | 25°C (Table 25) |