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. Sealing shall be tight and reliable, without visible cracks or. cable trays are equivalent. The mechanical and electrical characteristics, tests, certifications, overall quality management, recommendations mentioned in this technical guide only apply to our own cable management ranges and cannot under any circumstances be transposed to si osure, overheating or. association representing the major electrical equipment manufac-turers in the U. This means that the technical equipment is protected against corrosion and the operatio-nal safety is increased at the same time. The seal has an additional protective functi-on: no rodents or reptiles can. Scope: Firestopping for busway, cable trays, cables, and trunking passing through walls in enclosed electrical installations. Where cables pass through shafts, walls, slabs, or enter electrical panels or cabinets, openings shall be tightly sealed with firestopping materials in accordance with. Cable tray installation must comply with specific technical standards to ensure electrical safety, system reliability, and long-term maintainability. Route. The following pages address the 2014 National Electrical Code® requirements for cable tray systems as well as design solutions from practical experience.