Fill Limits: For power cables, the fill must not exceed 40% of the tray's cross-sectional area; for control cables, it's 50%. NEC Article 392 outlines the key rules for installing and maintaining industrial cable tray systems. These systems, made from metal or plastic, are open structures designed to support electrical conductors, ensuring proper organization and safety. Here's what you need to know: Cable Types: Only use. cable trays are equivalent. The mechanical and electrical characteristics, tests, certifications, overall quality management, recommendations mentioned in this technical guide only apply to our own cable management ranges and cannot under any circumstances be transposed to si osure, overheating or. The primary rulebook used in the safe use of cable trays is NEC Article 392. You should consider it as a series of instructions that make the buildings resistant to. Only approved tray-rated cables should be installed. For licensed electricians, mastering these principles is essential. Cable tray is the preferred wiring method for industrial facilities, data centers, and large commercial buildings where routing dozens or hundreds of cables through individual conduits would be impractical and expensive.