Can cable trays be sealed up

Cable trays should be sealed using fire-rated materials and proper installation techniques to ensure safety, prevent fire spread, and maintain structural integrity.

Firestopping and Penetration Sealing

When cable trays pass through walls, floors, or slabs, all openings must be tightly sealed with firestopping materials such as fire-rated boards, firestop packs, firestop mastic, or fire-resistant mineral wool . For large openings, a fire-resistant backing plate should be installed before sealing. The seal must be tight and reliable, without visible cracks or voids, and all gaps inside and around metal trunking must be completely filled both internally and externally . Cover plates should be square, evenly painted, and properly dimensioned to close the opening securely.

Material Selection

• Firestop packs: Place in an orderly sequence, ensuring the gap area between packs and cables does not exceed 1 cm², with a minimum packing thickness of 24 cm .
• Mineral wool with fire-retardant coating: Often used in soft penetration seals, with thickness adjusted according to cable type and number of cable groups .
• Firestop mastic: Applied to fill small gaps and ensure a continuous seal around cables and trays .

Installation Considerations

• Maintain adequate spacing between cables to prevent heat accumulation and allow airflow, especially in perforated or wire mesh trays .
• Ensure tray connections are firm, straight, and properly aligned, with grounding continuity verified .
• For slab penetrations, provide 20–30 mm of firestopping and install a fire-support plate at the top, with a waterstop of at least 50 mm at floor level .
• Layout and positioning should facilitate installation and maintenance, avoiding obstruction of cables or access points .

Inspection and Maintenance

• Periodically inspect trays for corrosion, moisture, UV damage, or coating degradation .
• Check the integrity of fireproof seals and ensure no gaps or cracks have developed over time .
• Suspend use and inspect immediately if any abnormalities such as deformation or corrosion are detected .

Compliance

Sealing methods should comply with relevant standards, such as EN 1366-3 for cable penetration testing and EN 13501-2 for fire classification . The fire resistance of the seal depends on the type of mineral wool, installation method, and cable configuration, so proper classification and adherence to tested systems are essential . By following these guidelines, cable trays can be effectively sealed to provide fire protection, structural safety, and long-term reliability.