Cable Sizing & Protection Calculator
Enter the supply, load and installation details below. The tool derives design current, applies temperature and grouping derating, checks voltage drop and short-circuit withstand, and recommends a cable cross-section with a step-by-step calculation trace and a printable report.
01 Supply & load
Defines the design current the cable must carry continuously.
02 Cable construction & installation
Determines the base current-carrying capacity (ampacity) before derating.
Number of loaded circuits touching or in the same tray/duct.
03 Protection & compliance
Checks device coordination, fault withstand, and the voltage-drop limit.
↓ Calculation trace
Every step used to reach the recommendation, in order.
✓ Result
—
recommended conductor cross-section
Design notes
Cable Sizing Calculation Report
Generated for reference; verify against manufacturer ampacity tables, site earthing design, and applicable local code before installation.