How To Select Earthing Cable Size New! Here

Follow these 5 key steps based on and BS 7671 (common international standards). For NEC (US), refer to Table 250.122.

How to Select the Correct Earthing Cable Size (Step-by-Step Guide) how to select earthing cable size

Regardless of the calculation, standards often dictate minimum sizes for mechanical durability to prevent the cable from snapping during installation or maintenance. Follow these 5 key steps based on and

| Cross-sectional Area of Phase Conductor ($S_phase$) | Minimum Cross-sectional Area of Earth Conductor ($S_earth$) | | :--- | :--- | | | $S_earth = S_phase$ (Same size) | | $16 \text mm^2 < S_phase \le 35 \text mm^2$ | $S_earth = 16 \text mm^2$ | | $S_phase > 35 \text mm^2$ | $S_earth = S_phase / 2$ (Half size) | | Cross-sectional Area of Phase Conductor ($S_phase$) |

If you use a Copper earth cable with an Aluminum phase cable, the copper earth cable can be smaller in physical diameter than the aluminum phase cable, as copper is a better conductor. You must perform the Adiabatic Calculation (Section 4) to verify the size.

$$S = \frac\sqrt10,000^2 \times 0.1143 = \frac\sqrt10,000,000143 = \frac3162143 \approx 22.1 \text mm^2$$

Example NEC: 100A breaker → 8 AWG copper ground (approx 8.4 mm²).