For large openings, install a fire-resistant backing plate before sealing. Layout and positioning must be reasonable to facilitate installation and maintenance. Choose appropriate fire protection materials, such as fire-rated board, firestop packs, firestop mastic, or. 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. The built in spare capacity makes it easy to open up the seal and change or add cables, without punching new holes or adding material, whenever there is a need. What is a Cable Entry Seal? A cable entry seal is a specialized fitting that creates a secure, watertight, and dustproof barrier where cables pass through a. maintain spacing or to keep cables in place when the tray is ect the minimum bend ra-dius for cables as they exit the bottom of the cable tray. A rung spacing of 6 to 9 inches (150 to 230 mm) is preferable when the cable tray cont d for instrumentation and control applications that require. SLIPSIL Sealing Plugs are an ideal solution for the fire-safe, gas and / or watertight sealing of penetrations carrying single or multiple pipes. The last part of our penetration seal series of articles.