Cable trays and pipes passing through walls

Cable trays and pipes passing through walls must be properly firestopped and sealed to prevent fire and smoke spread, using approved materials and installation methods.

Fire Safety Considerations

When cable trays or pipes penetrate walls, especially fire-rated walls, they create potential pathways for fire and smoke. Metal cable trays can conduct heat, potentially igniting materials on the opposite side, so intumescent coatings or firestop systems are required on both sides of the wall if penetration occurs . All gaps around penetrants must be sealed tightly to maintain the wall's fire-resistance rating .

Firestopping Materials and Methods

Common firestopping solutions include:

• Firestop packs and mineral wool: Used to fill gaps around cables and pipes, with packing thickness typically not less than 24 cm and gaps not exceeding 1 cm² .
• Firestop mastic or putty: Applied to seal small openings and irregular gaps around penetrants .
• Fire-rated boards and backing plates: Installed for larger openings to provide structural support and fire resistance .
• Intumescent coatings: Expand under heat to seal penetrations and protect combustible materials .
• Pipe collars: Specifically designed for plastic pipes to prevent fire spread through wall voids .

Installation Guidelines

• Sequence: Install cable trays or pipes first, then apply firestopping materials in an orderly sequence .
• Mixed penetrations: When multiple services (cables and pipes of different materials) pass through the same opening, ensure the penetration seal is tested and approved for mixed use according to standards like EN 1366-3 .
• Spacing and layout: Maintain minimum distances between penetrants to ensure stability and fire resistance .
• Cover plates: Use square, evenly painted cover plates to close openings and maintain aesthetics and protection .
• Waterstops: For slab penetrations, a waterstop of at least 50 mm is recommended, with 20–30 mm of firestopping above the slab .

Standards and Compliance

• European Standards: EN 1366-3 specifies testing for cable and pipe penetration seals, while EN 13501-2 classifies fire resistance .
• Manufacturer approvals: Only use firestop products tested for the specific combination of penetrants, diameters, and opening sizes .
• Inspection: Ensure all firestopping is tight, reliable, and free of visible cracks or voids .

Key Takeaways

Properly sealing cable trays and pipes through walls is critical for fire safety, regulatory compliance, and building integrity. Use tested firestop systems, maintain correct spacing, and follow installation sequences to ensure that penetrations do not compromise the fire-resistance of walls or floors. Regular inspection and adherence to standards are essential for long-term safety.