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. Electrical cable tray wall penetration firestopping 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. 3M Fire Barrier Moldable Putty+ is a one-part, halogen-free product designed to firestop electrical outlet boxes and a wide variety of through-penetrations including cable, conduit, insulated pipe and metal pipe, which penetrate fire-rated construction. These systems prevent fire and smoke from spreading through open cable pathways, maintaining circuit integrity and code. The Ladder Type Cable Trays SIESA® offer a reliable and safe solution for the management of electrical cables and instrumentation. Route. Effective protection of cable systems around the world: our tried-and-tested FLAMMOTECT-A and DG-CR 0. 7 products are successfully used to protect cables in high-rise buildings, industrial buildings, and offshore facilities as well as in sensitive areas, such as hospitals, airports, production.