High-voltage systems place different priorities on tray selection compared to low-voltage or control cabling. Ventilated Tray or Cable Ladder: The Preferred Choice. There is a great need to have a powerful, robust system in handling the high-voltage cables since they are heavy and extremely hot. In my experience, thick metal can be used to avoid sagging. Unlike low-voltage installations, high-voltage cable tray systems must handle higher current loads, greater heat generation. Cable tray types, fill rules for single-conductor and multiconductor cables, ampacity derating, separation requirements, and when to use tray vs conduit. These cables are commonly used in industrial, commercial, and utility applications.