Installing cable trays helps meet industry standards and regulations for electrical safety. They provide a safe, organized, and efficient way to route and support cables, while also protecting them from damage and interference. However, not all installations require cable trays, and it's. The primary rulebook used in the safe use of cable trays is NEC Article 392. 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. NEC Article 392 governs cable tray systems. Grounding and bonding are mandatory for metallic trays.