Grounding: Metallic trays can serve as equipment grounding conductors (EGC) if they meet NEC requirements. Fill Limits: For power cables, the fill must not exceed 40% of the tray's cross-sectional area; for control cables, it's 50%. Hubbell Wiring Device-Kellems and Hubbell Premise Wiring are divisions of Hubbell Incorporated, a U. headquartered manufacturer with over 130 years of supplying solutions for the electrical and data markets. The metal in cable trays may be used as the EGC as per the limitations. Cable tray systems have become an essential component in the infrastructure of modern commercial buildings, smart offices, data centers, and various industrial facilities. These systems provide an efficient and adaptable solution for managing a wide range of cables, including power cables, control. NEC Article 392 outlines the key rules for installing and maintaining industrial cable tray systems. Here's what you need to know: Cable Types: Only use. us-trations without notice. The mechanical and electrical characteristics, tests, certifications, overall quality management, recommendations mentioned. The primary rulebook used in the safe use of cable trays is NEC Article 392. This is a description of how to select, install, and support these metal or plastic frames, on which electrical wires are installed.