The standard NEMA lengths for cable tray are 12, 20, 24 and 30-feet, although some manufacturers like Eaton offer cable tray in lengths up to 40 feet. Selecting a cable tray length is based on several criteria, including: The required load that the cable tray must. 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. us-trations without notice. All illustrations, descriptions and technical information included in this document are provided as indications and can cable trays are equivalent. The mechanical and electrical characteristics, tests, certifications, overall quality management, recommendations mentioned. National Electrical Code (NEC) specifies the capacities of cables rated at 2000 volts or less in cable trays. Single Conductor Cables enable cables of equivalent construction & conductor material to be functioned at varying maximum ampacities based on how the cables are physically placed in ladder. Hubbell's NEXTFRAME® Ladder Tray is the effective and widely used cable runway that supports and delivers bundles of cable between cabinets, racks, and closets, along walls, and suspended from ceilings. The Ladder Tray features light, rugged, tubular steel construction. It is designed for. 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. Firestop systems are required at penetrations. Understanding NEC Article 392: Cable.