Atkore Trof is a prefabricated mill-galvanized steel structure consisting of ventilated or solid bottoms, welded to the side rails, and is manufactured and tested to NEMA Standard VE-1Atkore Trof is a prefabricated mill-galvanized steel structure consisting of ventilated or solid bottoms, welded to the side rails, and is manufactured and tested to NEMA Standard VE-1maintain 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. Our cable tray design considerations guide details key factors to consider when designing cable tray systems for industrial and commercial applications. The I-beam design is the most common cable tray construction. But before you lay the first tray or clamp down a single cable, you need a solid plan.