NEC Article 392 governs cable tray systems. Grounding and bonding are mandatory for metallic trays. Tray fill limits must be calculated properly. Firestop. However, not all installations require cable trays, and it's essential to understand when and why you should use them. 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. Answer: No. 305(a)(3), or comparable standards promulgated by States operating OSHA-approved State plans. In addition, this document contains several references to provisions of the National Electric Code.