Vertical Runs: For vertical cable runs within trays, cables should be secured at the top and every 1. All bends must be securely fastened. Binding: When. 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. Article Summary: A compliant cable tray installation requires a thorough understanding of NEC Article 392, proper structural support, and precise installation techniques. The Cable Tray system is installed in electrical rooms, plant rooms, and service corridors. Adherence to these guidelines is essential: 1.