Cable Calc | Formula __link__

[ V_d = \sqrt3 \cdot I \cdot L \cdot (R \cos\phi + X \sin\phi) \quad \text(3-phase) ]

[ F_harmonic = \frac1\sqrt1 + \sum_h=3,5,7... \left(\fracI_hI_1\right)^2 \cdot h^0.5 ] | Standard | Approach | Key Features | |----------|----------|---------------| | NEC (USA) | Table-based | Ampacity tables, 60/75/90°C columns, adjustment factors | | IEC 60287 | Calculation | Explicit thermal resistance model (Rth), for complex installations | | BS 7671 | Mixed | Simplified tables + voltage drop formula | | IEEE 835 | Calculation | For large power cables, includes soil drying effects | cable calc formula

And always, always derate for grouping.