Sealing of multiple openings in cable trays

Openings in cable trays should be sealed using fire-rated or weatherproof materials to ensure safety, prevent fire and smoke spread, and maintain environmental protection.Firestopping RequirementsWhen cable trays pass through walls, floors, or slabs, all openings must be tightly sealed with firestopping materials to comply with design and safety standards. The seal must be reliable, without visible cracks or voids, and for large openings, a fire-resistant backing plate should be installed before sealing. Common fire protection materials include fire-rated boards, firestop packs, firestop mastic, and fire-resistant mineral wool. Gaps between firestop packs and cables should not exceed 1 cm², and packing thickness should meet minimum design requirements, typically around 24 cm .Fireproof Pillows and Intumescent SolutionsProducts like AF Bags are intumescent and ablative fireproof pillows certified under EN 1366-3, capable of sealing cable tray penetrations up to EI 240. They are designed to fit even thin structures without additional framing and can be repositioned for maintenance. The sealing depth for cables up to 21 mm in diameter is typically 120 mm, and multiple pillows can be used to completely close larger penetrations .Weatherproof and Environmental SealsFor outdoor or wet environments, CSD WSP weatherstops provide a waterproof and corrosion-resistant seal around cable trays, conduits, or bus ducts. These systems use a steel frame with layered water-resistant pads and silicone-based sealant, ensuring a weathertight seal while allowing easy cable maintenance . Similarly, SLIPSIL sealing plugs offer fire-safe, gas-tight, and watertight sealing for single or multiple cable penetrations, using expanding rubber inserts and sealants for a secure fit .Installation ConsiderationsMeasure the cable tray dimensions to determine the number and size of sealing units required.Install fire-support plates at slab penetrations and maintain a firestopping layer of 20–30 mm where applicable .Ensure cover plates are square, evenly painted, and properly dimensioned to close the opening.Maintain orderly placement of firestop packs and verify that all gaps inside and around metal trunking are sealed both internally and externally .For maintenance, choose systems that allow easy repositioning or removal without compromising the seal .Compliance and SafetyAll sealing systems should comply with local building codes and fire safety regulations, and their performance must be verified through fire tests. Using certified products ensures that the building's fire resistance and environmental protection are maintained, preventing the spread of fire, smoke, or water through cable tray openings . By following these guidelines and selecting appropriate sealing materials, cable tray openings can be effectively protected against fire, smoke, and environmental hazards while allowing for safe maintenance and modifications.