The condition:
[ A_min = \sqrt\fracI_sc^2 \times tk ]
| Number of circuits | k₂ (touching, in air) | |-------------------|------------------------| | 1 | 1.0 | | 2 | 0.80 | | 3 | 0.70 | | 4 | 0.65 | | 5 | 0.60 | | 6 | 0.57 | | 8 | 0.52 |
The actual ampacity (I_actual) is:
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:
The condition:
[ A_min = \sqrt\fracI_sc^2 \times tk ]
| Number of circuits | k₂ (touching, in air) | |-------------------|------------------------| | 1 | 1.0 | | 2 | 0.80 | | 3 | 0.70 | | 4 | 0.65 | | 5 | 0.60 | | 6 | 0.57 | | 8 | 0.52 |
The actual ampacity (I_actual) is:
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: