Cable Selection | Calculation

This is the most commonly skipped calculation, and it's a killer. The cable's earth conductor (or armour, or separate PE) must have low enough impedance that a phase-to-earth fault draws enough current to trip the protective device within the required time (0.4s for final circuits per IEC 60364).

Where:

The UI should function as a "Wizard" with real-time feedback. cable selection calculation

Adjust the cable size based on the installation method:

The actual ampacity (I_actual) is:

Assuming an ambient temperature of 35°C:

Before selecting a cable, several factors need to be considered: This is the most commonly skipped calculation, and

The most dangerous oversight. According to Neher-McGrath (the foundation of both IEC and NEC ampacity tables), the derating for (n) equally loaded cables is severe: