Check voltage drop or find a minimum conductor size with the simplified Table C8 method.
Simplified copper voltage-drop lookup. Does not establish ampacity, protective-device coordination or total installation compliance.
Results
Enter the required values, then press Calculate.
How this works
Uses the AS/NZS 3000 Appendix C4 / Table C8 shortcut: %Vd = (length × current) ÷ table value (m·A per %Vd). PVC/PVC at 75 °C, 230 V single-phase or 400 V three-phase.
Not the AS/NZS 3008 impedance method. Guidance only; check the Rules and your job before you rely on it.
Which voltage drop method does this calculator use?
The simplified method of AS/NZS 3000:2018 Appendix C (Paragraph C4) with Table C8, which gives ampere-metres per 1% voltage drop for each cable size. Table C8 is built from AS/NZS 3008.1.1 values for common PVC/PVC cables at 75 °C, at 230 V single-phase and 400 V three-phase.
What is the voltage drop limit under AS/NZS 3000?
Clause 3.6.2 caps the total drop between the point of supply and every point in the installation at 5% of nominal voltage. The cap is 7% when the installation has its own substation on the premises and is measured from that substation. Sharing the allowance between consumer mains, submains and final subcircuits is up to the designer.
What current should I use for a voltage drop calculation?
Clause 3.6.2 lets you use the lowest of the connected load, the maximum demand and the protective device rating. Where the load is spread along a final subcircuit, as on socket-outlet and lighting circuits, Exception 1 allows half the device rating.
When should I use AS/NZS 3008 instead of Table C8?
Table C8 suits common PVC/PVC cables. For other cable types, higher operating temperatures or circuits where the margin is small, calculate voltage drop with the AS/NZS 3008.1.1 values for the actual cable and installation.
