Fittings can, on the one hand, be used for horizontal or vertical changing of the routing direction or, on the other, to change the height or width of the dimension. It also helps reduce the risk of. maintain spacing or to keep cables in place when the tray is ect the minimum bend ra-dius for cables as they exit the bottom of the cable tray. A rung spacing of 6 to 9 inches (150 to 230 mm) is preferable when the cable tray cont d for instrumentation and control applications that require. 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. The cable support lengths and fittings can basically be designed as cable trays, cable ladders or mesh cable trays, in which cables are routed. This section will guide you through the necessary steps to ensure a successful. IEC 61537 is the internationally recognized benchmark for metal cable tray systems. It applies to cable trays made of steel, stainless steel, aluminum, or other metallic materials. The standard ensures these systems can handle the physical and electrical loads they're exposed to over time.