Cable tray types
Per IEC 61537: ladder (power cables, maximum load capacity), perforated (universal), wire mesh (light, for low-current networks), solid (for fire-hazard zones).
Fill factor
Total cable cross-section must not exceed 40% of tray cross-section for power circuits and 50% for control. Formula: Scable = Σ(π × d² / 4) × 1.1 (safety factor for uneven laying).
Calculation example
Given: 12 cables 5×2.5 mm² (d=10.2 mm), 5 cables 5×6 mm² (d=13.5 mm). Total area: S = 12 × 81.7 + 5 × 143.1 = 1696 mm². With 1.1 factor: 1865 mm². At 40% fill: Stray ≥ 1865 / 0.4 = 4663 mm² → select 200×50 tray (usable area ≈ 6000 mm²).