The minimum cross-sectional area to withstand a short circuit is given by the (IEC 60364-4-43):
The corrected ampacity (I_z) must be ≥ I_b. electrical cable calculation
Example: A 10 kW, three-phase motor at 400V with power factor 0.85: [ I_b = \frac100001.732 \times 400 \times 0.85 \approx 17 , A ] A cable’s tabulated current rating (I_t) is given for standard conditions (e.g., 30°C ambient, free air or buried). Real installations rarely meet these ideal conditions. You must derate the cable using factors from standards like IEC 60364 or NEC Table 310.15(B)(2)(a) . The minimum cross-sectional area to withstand a short