Sealing the inside of the cable tray

Cable tray penetrations should be sealed using fire-rated materials such as intumescent pillows, mineral wool, or firestop mastic to ensure safety, compliance, and maintain system integrity.

Fireproof Sealing Materials

Intumescent fireproof pillows (e.g., AF BAGS) are commonly used to seal cable tray penetrations. These pillows expand under heat to block fire and smoke, providing protection up to EI 240 according to EN 1366-3 standards. They are suitable for cables up to 21 mm in diameter and can be inserted even in thin structures without additional framing. The pillows are repositionable, facilitating maintenance or modifications, and do not contain harmful fibers . Mineral wool combined with fire-retardant coatings or mastic is another effective solution. Soft penetration seals use mineral wool of specific density and thickness, often coated with a water-based fire-stopping compound, to achieve fire resistance. The effectiveness depends on the cable type, installation method, and the density of the mineral wool . Firestop packs and boards can also be used for larger openings. These materials are placed in an orderly sequence, ensuring that gaps between the cables and the tray do not exceed 1 cm², and the packing thickness meets minimum requirements (e.g., 24 cm for certain applications), . Cover plates may be added to close the opening neatly and maintain a consistent appearance.

Installation Guidelines

1. Measure the cable tray dimensions to determine the number and size of sealing materials required .
2. Install a fire-resistant backing plate for large openings before inserting pillows or mineral wool .
3. Fill all gaps tightly, both inside and around the metal tray, to prevent smoke or fire passage .
4. Ensure accessibility for maintenance by using repositionable materials where possible .
5. Follow manufacturer instructions for compression, layering, and sealing depth to meet the certified fire rating .

Compliance and Standards

Sealing systems should comply with EN 1366-3 for fire resistance and EN 13501-2 for classification. The choice of sealing material may vary depending on cable type, tray configuration, and penetration size. Proper installation ensures that the fire rating is maintained and that the system remains safe during operation . By using these methods, the inside of a cable tray can be effectively sealed to prevent fire spread, maintain safety, and comply with regulatory standards.