Fireproofing and sealing of horizontal cable trays

Horizontal cable trays should be fireproofed using fire-blocking sections, fire-rated coatings, and sealing materials to prevent fire spread and maintain system safety.

Fireproofing Principles

Fireproofing of cable trays involves isolating potential fire sources and preventing flame propagation along the tray. Key principles include:

• Segregation of cables: Separate high-voltage power cables from low-voltage signal cables to reduce fire risk and electromagnetic interference ( ).
• Use of fireproof trays: Only trays designed for fire containment should be used; avoid modifying or damaging tray coatings ( ).
• Fire-blocking sections: Install fire-blocking partitions at intervals along the tray to isolate sections and prevent fire spread. These sections should maintain stability under high temperatures, water immersion, or rodent damage ( ).

Materials for Fireproofing

Common materials for fireproofing and sealing horizontal cable trays include:

• Fireproof boards and coatings: Provide a protective layer around cables; suitable for indoor and outdoor use ( ).
• Intumescent caulks and putties: Expand under heat to seal gaps and prevent fire and smoke penetration, e.g., IC 15WB Caulk or 3M Fire Barrier Moldable Putty+ ( ).
• Firestop packs and mineral wool: Used to fill gaps around cables and tray penetrations through walls or floors; ensure packing thickness and gap limits are maintained ( ).
• Fireproof bags or mud: Offer localized protection for cable bundles, with good heat dissipation and ease of maintenance ( ).

Installation and Sealing Techniques

• Tray penetrations: Seal openings where trays pass through walls, floors, or ceilings using fire-rated materials to maintain fire resistance ( ).
• Gap management: Ensure gaps between firestop materials and cables do not exceed 1 cm², and packing thickness is at least 24 cm for effective fire containment ( ).
• Layering and coverage: Apply coatings or wraps evenly around cables; cover cut edges and joints to ensure complete encapsulation ( ).
• Heat dissipation: Use perforated or wire mesh trays to maintain airflow and prevent heat accumulation, which can compromise fireproofing ( ).

Inspection and Maintenance

• Routine checks: Inspect fireproof coatings, seals, and tray integrity periodically to detect corrosion, deformation, or damage ( ).
• Maintenance of fire-blocking sections: Repaint or replace materials as needed to maintain fire resistance and long-term effectiveness ( ).
• Environmental considerations: For outdoor trays, monitor for UV damage, moisture, or chemical exposure that may degrade fireproofing ( ).

Standards and Compliance

• Fire-blocking sections should meet national standards such as GB23864, with a minimum fire resistance of 1 hour ( ).
• Materials must maintain performance under high temperatures and comply with physical and chemical stability requirements ( ). By combining fire-blocking sections, fire-rated coatings, intumescent sealants, and proper installation practices, horizontal cable trays can achieve effective fire containment, ensuring safety, regulatory compliance, and operational reliability.