Cable trays and busways at floor level or at slab penetrations shall have a waterstop no less than 50 mm in height. At slab penetrations, provide 20–30 mm of firestopping and install a fire-support plate at the top. They provide robust support for cables while ensuring fire safety in extreme conditions. Where cables pass through shafts, walls, slabs, or enter electrical panels or cabinets, openings shall be tightly sealed. Cable tray installation must comply with specific technical standards to ensure electrical safety, system reliability, and long-term maintainability. Route. The International Electrotechnical Commission (IEC) provides detailed guidelines for cable tray systems under IEC 61537. Whether you're designing a new. 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).