The majority of the sections have a length of 3 meters, as this is easy to transport and can be compactly placed on the shipping trucks. Proper tray and ladder sizing ensures safe, efficient, and maintainable electrical installations in all engineering applications. IEC 61537 and IEC 60364 require evaluating tray dimensions based on cable quantity, type, and layout configuration. IEC 61537 covers cable tray and cable ladder systems for the support and accommodation of cables, while NEC Article 392 governs cable. The formula used to calculate cable tray capacity is: Cable Tray Capacity = (Tray Width × Tray Depth × Fill Ratio) / Cable Cross-sectional Area Where: Tray Width is the internal width of the cable tray in meters (or millimeters). Tray Depth is the internal depth of the cable tray in meters (or. This publication is intended as a practical guide for the proper and safe* installation of cable ladder systems, cable tray systems, channel support systems and associated supports. Cable ladder systems and cable tray systems shall be manufactured in accordance with BS EN 61537, channel support. Ladder cable tray is available in widths of 6, 9, 12, 18, 24, 30, 36, 42 and 48 inches with rung spacings of 6, 9, 12 or 18 inches. Note that wider rung spacings and wider cable tray widths decrease the overall strength of the cable tray.