Cable Calc Formula _verified_ May 2026

[ I = \sqrt\frac\theta_max - \theta_ambR_dc \cdot \left(1 + \alpha(\theta_max - 20)\right) \cdot \left( R_th \right) ]

: [ S_min = \frac25,000 \cdot \sqrt0.2143 \approx \frac25,000 \cdot 0.447143 \approx 78 , mm^2 ] 185 mm² >> 78 mm² — thermal withstand OK. cable calc formula

[ S = \fracI_sc \cdot \sqrttk ]

[ \boxedS = \max\left( S_ampacity, S_V_d, S_short-circuit \right) ] [ I = \sqrt\frac\theta_max - \theta_ambR_dc \cdot \left(1

For AC circuits:

[ I_rms = \sqrtI_1^2 + I_2^2 + ... + I_h^2 ] And derating factor: 000 \cdot \sqrt0.2143 \approx \frac25