Earth Cable Sizing -

| Phase Conductor (mm²) | Min. Copper Earth (mm²) – if same material | |-----------------------|---------------------------------------------| | 1.5 | 1.5 | | 2.5 | 2.5 | | 4 | 4 | | 6 | 6 | | 10 | 10 | | 16 | 16 | | 25 | 16 | | 35 | 16 | | 50 | 25 | | 70 | 35 | | 95 | 50 | | 120 | 70 |

When in doubt: . The cost of one cable size up is trivial compared to the cost of a failed protection path. earth cable sizing

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