Size Calculator - Earthing Cable

The key formula (from IEC 60364-5-54, clause 543.1.2) is:

Introduction An earthing (or grounding) system is the backbone of electrical safety. Its primary role is to provide a low-impedance path for fault currents to flow safely to the earth, triggering protective devices (like fuses or circuit breakers) and preventing dangerous voltage build-up on equipment enclosures. earthing cable size calculator

[ S = \frac\sqrtI^2 \times tk ]

( S = \frac\sqrt15000^2 \times 0.1143 ) ( S = \frac15000 \times 0.316143 ) ( S = \frac4743143 \approx 33.2 \text mm^2 ) The key formula (from IEC 60364-5-54, clause 543

| Parameter | Description | Example | |-----------|-------------|---------| | | Maximum prospective earth fault current at the point of installation | 10 kA (10,000 A) | | Fault clearing time (t) | Operating time of the upstream overcurrent device (fuse/MCCB) | 0.2 seconds | | Material | Copper (most common), Aluminum, or Galvanized Steel | Copper | | Insulation type | PVC (lower k value), XLPE (higher k value), bare conductor | PVC (k = 143 for Cu) | | Initial & final temperature | Defaults based on standard (e.g., 30°C initial, 160°C final for PVC-insulated Cu) | Embedded in k factor | Step-by-Step Working Example (IEC Method) Scenario: A 415V industrial panel has a prospective earth fault current of 15 kA. The upstream MCCB trips in 0.1 seconds. The earthing conductor is copper with PVC insulation (k = 143). Find the minimum size. The upstream MCCB trips in 0