Fireproof sealing methods for cable tray openings in vertical shafts

Cable tray openings in vertical shafts should be sealed using fire-rated materials such as intumescent pillows, firestop packs, mineral wool, or firestop mastic to achieve a reliable fireproof barrier.

Key Principles

Fireproof sealing of cable tray penetrations in vertical shafts is essential to prevent the spread of fire and smoke between floors. Openings must be tightly sealed without visible cracks or voids, and the layout should allow for installation, maintenance, and future cable modifications .

Recommended Materials

• Intumescent fireproof pillows: These expand under heat to seal gaps around cables and trays. Products like AF BAGS are certified under EN 1366-3 for up to EI 240 fire resistance and can accommodate cables up to 21 mm in diameter .
• Firestop packs and mineral wool: Used to fill gaps around cable trays, ensuring a minimum packing thickness (e.g., 24 cm) and limiting gaps to 1 cm² .
• Firestop mastic or caulk: Intumescent caulks like IC 15WB can seal edges and small gaps, providing smoke and fire containment .
• Fire-rated boards or backing plates: For large openings, a fire-resistant backing plate should be installed before sealing to support the firestop material .

Installation Guidelines

1. Prepare the shaft: Ensure floor and wall finishes are complete, and shaft doors are installed .
2. Measure and select materials: Determine cable tray dimensions and choose the appropriate number and size of firestop pillows or packs .
3. Install backing plates: For large openings, place a fire-resistant plate to support the firestop material .
4. Pack the opening: Insert firestop packs or pillows in an orderly sequence, ensuring all gaps around cables and trays are sealed both internally and externally .
5. Seal edges: Apply firestop mastic to cover edges and ensure a continuous barrier .
6. Cover plates: Use square, evenly painted cover plates to close the opening, maintaining aesthetics and protection .

Fire Ratings and Compliance

• Firestop systems are rated according to EI (integrity and insulation) standards, with common ratings for cable tray penetrations ranging from EI 120 to EI 240 .
• UL-listed systems and EN-certified products ensure compliance with local fire codes and provide tested performance for walls, floors, and vertical shafts .

Maintenance and Flexibility

Modern firestop systems, such as FIRSTO modular systems, allow for easy addition or removal of cables without compromising fire protection . Intumescent pillows and modular packs are particularly suitable for vertical shafts where access may be limited.

Summary

To fireproof cable tray openings in vertical shafts effectively:

• Use intumescent pillows, firestop packs, mineral wool, or mastic.
• Ensure tight, void-free sealing with proper backing plates for large openings.
• Follow fire rating standards (EI 120–240) and UL/EN certifications.
• Maintain accessibility for future cable modifications. This approach ensures fire safety, regulatory compliance, and long-term reliability in vertical electrical shafts.