How to Find the Right Cable Size: The Essential Formula Explained
[ \boxedA = \frac2 \rho I LV_d ]
Choosing the wrong cable size isn't just inefficient—it's dangerous. Undersized cables overheat, cause voltage drops, and can start fires. Oversized cables waste money and are difficult to install.
So, how do you calculate the exact size you need? You don’t need a crystal ball; you need and the Voltage Drop Formula .
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:
[ A = \frac2 \times \rho \times I \times LV_d ]