The National Electrical Code (NEC) lays out specific guidelines regarding which cables are permitted for use in these trays, ensuring safety and compliance with industry standards. This standard specifies the requirements for nonmetallic cable trays and associated fittings designed for use in accordance with the rules of the Canadian Electrical Code (CEC) Part 1, and the National Electrical Code® (NEC). The technical content of IEC publications is kept under constant review by the IEC. Where necessary, cable tray systems and cable ladder. l Code (U.