[ A_min = \sqrt\fracI_sc^2 \times tk ]
That means a cable rated for 100A in free air can only carry in this installation. This is why we oversize. The Grouping Trap (k₂) The most dangerous oversight. According to Neher-McGrath (the foundation of both IEC and NEC ampacity tables), the derating for (n) equally loaded cables is severe: cable selection calculation
[ Z_loop \times I_a \leq U_0 ]