National Electrical Code (NEC) provisions govern perforated cable tray installations in the United States, specifying requirements for cable types, support methods, grounding provisions, and installation clearances. It is the first joint effort of NEMA and CSA International to put in one place standards for metal trays per both NEMA and CSA methods. Addresses shipping. 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. Cable Tray Types and When to Use Each 2.