To calculate the cable tray capacity, multiply the width and height of the cable tray to find the total area, then multiply by the fill ratio. Divide this by the cross-sectional area of a single cable to find the capacity. Use the floor function to ensure you get a. Cable tray types, fill rules for single-conductor and multiconductor cables, ampacity derating, separation requirements, and when to use tray vs conduit. Cable tray is the preferred wiring method for industrial facilities, data centers, and large commercial buildings where routing dozens or. This is a description of how to select, install, and support these metal or plastic frames, on which electrical wires are installed. You should consider it as a series of instructions that make the buildings resistant to electrical fires or broken wires. 16, tray fill, ampacity adjustment, voltage-drop checks, grounding, and IEC design cross-checks. Use NEC 392 for tray rules, but still size conductors from NEC 310. Here's what you need to know: Cable Types: Only use.