[ A = \frac{I \times \rho \times L}{V_d} ]
Most guides present cable sizing as a neat two-step formula: calculation of cable size formula
Where: ( A ) = cross-sectional area (mm²) ( I ) = current (A) ( \rho ) = resistivity (Ω·mm²/m) ( L ) = cable length (m) ( V_d ) = permissible voltage drop (V) [ A = \frac{I \times \rho \times L}{V_d}