[ A = \frac2 \times \rho \times I \times LV_d ]
Here is the standard engineering formula used to find the minimum cable size (cross-sectional area) for a circuit. The most common formula to calculate the minimum required cable cross-sectional area (in mm²) is: how to find the cable size formula
So, how do you calculate the exact size you need? You don’t need a crystal ball; you need and the Voltage Drop Formula . [ A = \frac2 \times \rho \times I