Fireproof openings of cable trays should be sealed using fire-rated materials such as firestop packs, intumescent caulks, or modular firestop systems to prevent fire and smoke spread while maintaining accessibility for maintenance.

Key Principles

Firestopping is essential wherever cable trays pass through walls, floors, or slabs to maintain the integrity of fire-rated barriers. Openings must be tightly sealed without visible cracks or voids, and large openings may require a fire-resistant backing plate before sealing to ensure stability and fire resistance .

Recommended Materials

• Firestop Packs and Mineral Wool: Used to fill gaps around cables; packing thickness should meet design requirements, typically not less than 24 cm, and gaps should not exceed 1 cm² .
• Intumescent Caulks and Mastics: Products like IC 15WB Caulk expand under heat to seal gaps and prevent fire and smoke penetration .
• Modular Firestop Systems: Systems such as FIRSTO allow easy installation around multiple cables or trays, provide mechanical load resistance, and enable future cable additions or removals .
• Fire-Rated Boards: Used for larger openings or as backing plates to support other firestop materials .

Installation Guidelines

1. Prepare the Opening: Ensure floor and wall finishes are complete, and shaft doors are installed. Clean surfaces for proper adhesion .
2. Install Backing Plates (if needed): For large openings, a fire-resistant plate provides support for firestop materials .
3. Apply Firestop Materials: Place firestop packs or mineral wool in an orderly sequence, ensuring all gaps around cables and trays are filled. Use intumescent caulk to seal edges and cut surfaces .
4. Cover Plates: Use square, evenly painted cover plates to close the opening, ensuring a neat and secure finish .
5. Compliance: Follow UL-listed systems and manufacturer instructions for specific tray sizes and wall types to achieve the required F- and T-ratings .

Maintenance and Inspection

• Routine Checks: Inspect fireproof trays and seals for corrosion, deformation, or damage.
• Re-sealing: Modular systems allow easy addition or removal of cables without compromising fire protection .
• Heat Dissipation: Maintain adequate spacing between cables and use perforated trays to prevent heat accumulation . By following these guidelines, cable tray openings can be effectively sealed to prevent fire and smoke propagation, comply with building codes, and maintain long-term safety and accessibility .