Note: If the derated capacity is lower than your protective device rating ($I_n$), you must select a larger cable size.
This guide is for educational and information purposes only. Electrical work must be carried out by a licensed electrician. All calculations and final selections must be verified against the specific clauses and tables in the current AS/NZS 3000 standard and relevant Australian Standards (e.g., AS/NZS 3008). as3000 cable selection
For most standard residential circuits, this is rarely the limiting factor, but it is mandatory for mains and sub-mains. Note: If the derated capacity is lower than
Voltage Drop Limits for Low Voltage Installations - ELEK Software All calculations and final selections must be verified
By following this guide and cross-referencing with the specific tables in (or .2), you ensure your cable selection is compliant, safe, and efficient.
| Requirement | Reference | Check | | :--- | :--- | :--- | | | AS3000 App B | Is the cable rated for the calculated load? | | 2. Derating | AS3008 | Have temperature and grouping been applied? | | 3. Voltage Drop | AS3000 2.6.2 | Is drop < 3% (Light) or < 5% (Power)? | | 4. Fault Loop | AS3000 2.6.3 | Is impedance low enough to trip the breaker? | | 5. Short Circuit | AS3000 2.5.2 | Will the cable survive a fault until the breaker trips? | | 6. Installation | AS3000 Sec 3 | Is the cable type suitable for the environment (e.g., UV exposure, water, mechanical damage)? |
The nominal current‑carrying capacity of a cable ((I_z)) must be at least the design current after applying all relevant factors from Appendix B: