How To Calculate Cable Sizes -

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

References: IEC 60364-5-52, BS 7671 (UK), NEC Article 310 (US), AS/NZS 3008 (Australia). how to calculate cable sizes

[ I_z \geq I_b ]

From IEC table – 2.5 mm² copper carries 24 A. Derating: ( C_t = 0.94 ) (35°C). ( I_z = 24 \times 0.94 = 22.56 A ) – adequate. PVC-insulated copper, clipped to wall (method C), ambient

[ V_d = \frac\sqrt3 \times L \times I_b \times (R \cos\phi + X \sin\phi)1000 \text (for 3-phase) ] clipped to wall (method C)

Voltage drop. For 2.5 mm² copper, ( R_ac ≈ 8.91 \text Ω/km ). Single phase drop = ( \frac2 \times 40 \times 21.74 \times 8.911000 = 15.5V ). 15.5V / 230V = 6.7% → exceeds 3% limit (6.9V max).