Fireproof sealing of wall-mounted cable trays

Cable tray penetrations through walls must be sealed with fire-rated materials to maintain wall integrity and prevent fire and smoke spread.Key PrinciplesFirestopping ensures that openings created by cable trays, busways, or trunking in walls and floors do not compromise the fire resistance of the structure. All penetrations must be tightly sealed without visible cracks or voids, and the seal should match the fire rating of the surrounding wall or floor . Proper sealing prevents the vertical spread of fire and smoke, particularly through the chimney effect in shafts or multi-story installations .Recommended MaterialsFirestop Packs and Mineral Wool: For large openings, install a fire-resistant backing plate and fill gaps with firestop packs or fire-resistant mineral wool. Packing thickness should meet design requirements, typically not less than 24 cm, and gaps around cables should not exceed 1 cm² .Firestop Mastics and Sealants: Use intumescent or ablative sealants to fill smaller gaps around cable trays, ensuring a continuous barrier .Certified Fireproof Pillows: Products like AF BAGS are intumescent and ablative pillows certified under EN 1366-3 for up to EI 240 fire resistance. They are suitable for cable diameters up to 21 mm and can be inserted into thin walls without additional framing .Modular Systems: Systems such as FIRSTO or SLIPSIL allow modular sealing around multiple cables or pipes, providing fire, water, and gas protection while facilitating maintenance .Installation GuidelinesMeasure and Plan: Determine the cable tray width and penetration size to select the appropriate sealing material or number of pillows .Prepare the Opening: Ensure wall finishes are complete and shaft doors installed. For large openings, install a fire-resistant backing plate before sealing .Seal the Penetration: Place firestop packs, pillows, or sealant in an orderly sequence, ensuring all gaps inside and around the tray are completely filled .Cover Plates: Use square, consistent cover plates to close the opening, painted evenly if required .Verification and Labeling: After installation, verify the seal's integrity and fire rating. Label the penetration with the installation date, fire resistance rating, and installer information .Maintenance and InspectionPeriodically inspect seals for cracks, displacement, or degradation.Ensure cable tray connections remain firm and aligned, and that grounding continuity is maintained .Replace or reposition fireproof pillows or sealants if modifications or maintenance require cable movement .Standards and CertificationEN 1366-3: Standard for fire resistance of service installations, including cable tray penetrations.EI Ratings: Ensure the seal matches the wall's fire rating (e.g., EI 120, EI 240) to maintain structural integrity .Only trained personnel or approved contractors should perform firestopping to ensure compliance and safety . By following these guidelines, cable tray penetrations can be effectively sealed to maintain fire-rated wall performance, prevent smoke and heat spread, and comply with safety regulations.