Table 310.15(C)(1): 7–9 conductors = 70% 47.85A × 0.70 = 33.5A
Neutrals that carry only unbalanced current (e.g., in a 3-phase wye system) are not counted. Neutrals that carry full load (e.g., single-phase, or non-linear loads with triplen harmonics) are counted. derating wire
NEC Table 310.15(B)(2)(a) for 45°C ambient, 90°C insulation = 0.87 55A × 0.87 = 47.85A Table 310
Continuous load must not exceed 80% of the derated ampacity (or conversely, the derated ampacity must be ≥ 125% of the continuous load). derating wire