Correction factors: k_t=1, k_g=1 → (I_t \ge 56.6) A.

VD (R = 2.2 Ω/km, X=0.09 Ω/km, cosφ=0.85, sinφ=0.527): [ V_d = \frac\sqrt3 \cdot 100 \cdot 56.6 \cdot (2.2\cdot0.85 + 0.09\cdot0.527)1000 \approx 18.4 \text V ] As % of 400V = 4.6% → exceeds 3% limit. Increase to 16 mm² (R=1.38 Ω/km). VD = 11.7 V → 2.9% OK.

[ I_b = \frac30000\sqrt3 \cdot 400 \cdot 0.85 \cdot 0.9 \approx 56.6 \text A ]

Short-circuit check: [ S_min = \frac\sqrt(5000)^2 \cdot 0.1143 \approx \frac1581143 \approx 11.1 \text mm^2 ] Selected 16 mm² > 11.1 mm² → OK.

From IEC table for XLPE/Cu, 10 mm² → ~70 A. Select 10 mm².

Mechanical strength satisfied (≥1.5 mm²).