Cable size calculator
Size your cable. Understand every constraint.
Calculation scope & engineering review
Uses documented AS/NZS 3008.1.1:2017 and AS/NZS 3008.1.1:2025 source data for supported calculations. Not independently verified by a licensed electrical engineer. Check results against the current published standards before use. New Zealand mode uses the 2017 Australian rating tables with New Zealand ambient conditions. Read assumptions and limitations.
Circuit requirements
Supply, load and allowable voltage drop
Standard
Load
kW and hp calculations use the specified load power factor. A and kVA calculations use worst-case cable impedance for voltage drop.
Voltage drop
Calculate (default): resistance is read at the actual calculated operating temperature under load. Maximum: always reads resistance at the insulation's own max permissible temperature — more conservative.
Cable specification
Conductor, insulation and cable configuration
Insulation
Cable type
Earth conductor settings
Earth core
Installation conditions
Installation method and environmental factors
Installation
04Protection checksOptional short circuit and loop impedance checks
Short circuit protection
Enter the maximum Ze from AS/NZS 3000 Table 8.1 for the actual protective device and required disconnection time.
Unavailable: device trip-curve coordination needs authoritative AS/NZS 60898 or manufacturer data. The available checks use the fault current, duration and maximum Ze that you enter.