How To Calculate Cable Sizes

$$I = \fracPV \times \textPower Factor$$

PVC-insulated copper, clipped to wall (method C), ambient 35°C, no grouping, length 40m. how to calculate cable sizes

$$I = \frac15000\sqrt3 \times 415 \times 0.85 \approx 24.6 \text Amps$$ clipped to wall (method C)

Despite 2.5 mm² handling the current, voltage drop forces 6 mm² cable for this 40m run. how to calculate cable sizes

To size a cable correctly, you must check it against three distinct criteria:

This is the most common reason for increasing cable size. As current flows through a cable, resistance causes a drop in voltage. Standards usually limit this to for lighting and 5% for power.