Cable Trays and Trunking — Selection

Fill factor

Per IEC 61537, the cross-section of cables in a tray should not exceed 40-50% of the tray area. For power cables without gaps — no more than 40%.

Tray types

Perforated trays — for cables up to 50 mm, with covers for dust protection; wire trays — light, for flexible cable; ladder trays — for heavy cables and large bundles.

Support spacing

Per IEC 61537: for trays up to 100 mm wide — 1.5 m, 100-300 mm — 2 m, over 300 mm — 3 m. Check deflection: less than 1/100 of span.

Fire barriers

Where cables pass through walls and floors — fire barriers with the correct rating (EI 30-120) per the building category.

Segregation

Power and low-current cables — separate trays or a partition. GorkyCAD marks cable routes by type automatically.

Practical numbers

A tray 200×50 mm with 40% fill holds about: 15 cables 5×2.5, or 6 cables 5×10, or 30 cables UTP.