Fire cable tray penetration through wall sealing

Cable tray penetrations through fire-rated walls must be sealed with firestop materials to prevent the spread of fire and smoke, using intumescent caulks, firestop packs, or modular systems designed for multi-cable applications.

Key Principles

Firestopping ensures that openings created for cable trays, busways, or conduits in walls or floors do not allow fire or smoke to spread. All gaps around the cable tray must be tightly sealed, without visible cracks or voids, and the installation should allow for future maintenance or cable additions .

Recommended Materials

• Firestop 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 manufacturer specifications, typically not less than 24 cm, and gaps around cables should not exceed 1 cm² .
• Intumescent Caulks: Products like IC 15WB Caulk or 3M Fire Barrier Moldable Putty+ expand under heat to seal gaps and prevent fire spread. These can be applied with standard caulking guns and are suitable for both new construction and retrofits .
• Modular Firestop Systems: Systems such as FIRSTO or Hilti cable transit frames allow easy installation around multiple cables or trays, provide mechanical load resistance, and enable future cable modifications without compromising fire protection .
• Cover Plates: Use square, consistent cover plates to close openings, ensuring a neat finish and additional fire protection .

Installation Guidelines

1. Prepare the Opening: Ensure wall finishes are complete and shaft doors installed. Clean the penetration area to remove debris.
2. Install Backing (if needed): For large openings, place a fire-resistant backing plate to support the firestop material.
3. Pack and Seal: Insert firestop packs or mineral wool around the cable tray, ensuring all gaps are filled. Apply intumescent caulk to seal edges and voids.
4. Check for Completeness: Verify that all gaps inside and around the tray are sealed both internally and externally. Ensure the seal is tight and continuous.
5. Install Cover Plates: Attach cover plates to protect the firestop and provide a finished appearance.

Benefits

Properly installed firestops:

• Prevent the spread of flames, smoke, and toxic gases through wall penetrations .
• Maintain the fire rating of walls and floors.
• Allow safe and flexible cable management for future modifications.
• Comply with building codes and fire safety standards. By following these guidelines and using certified firestop materials, cable tray penetrations can be safely sealed, ensuring both fire protection and operational flexibility.