Electrical cable trays passing through civil engineering walls

When electrical cable trays pass through walls, proper firestopping, sealing, and structural support are essential to ensure safety, compliance, and maintainability.

Firestopping and Penetration Sealing

Cable trays penetrating walls must be sealed with fire-rated materials to prevent the spread of fire and smoke. Openings should be tightly sealed using firestop packs, firestop mastic, mineral wool, or fire-rated boards, ensuring no visible cracks or voids remain. For large openings, a fire-resistant backing plate should be installed before sealing.

The gap between the firestop material and cables should not exceed 1 cm², and the packing thickness should be at least 24 cm. Preformed or reusable firestop elements, such as foam blocks or putty discs, allow for easy re-penetration during maintenance or cable upgrades, which is particularly important in mission-critical facilities like hospitals or data centers. These systems are tested to international standards (e.g., UL 1479, EN 1366-3) to ensure fire resistance and airflow control.

Cable Tray Design and Installation

Cable trays should be fireproof or coated for flame containment, and their structure must not be modified or damaged during installation. Perforated or wire mesh trays are recommended to improve airflow and heat dissipation, preventing overheating of cables. Maintain adequate spacing between cables and ensure tray connections are firm, straight, and properly aligned.

Grounding continuity should be verified, and mechanical damage should be avoided. The choice of tray material depends on the environment: aluminum offers corrosion resistance and light weight, while stainless steel provides high strength and durability in harsh conditions.

Compliance and Standards

Cable tray penetrations must comply with European Standard EN 1366-3 and be classified according to EN 13501-2 for fire resistance. Different cable types and configurations are tested to ensure the penetration seal maintains its fire rating. Soft penetration seals combining mineral wool and fire-retardant coatings are commonly used for cable bundles.

Inspection and Maintenance

Regular inspection is essential to ensure long-term effectiveness. Check for corrosion, deformation, or damage to trays, verify firestop integrity, and confirm that seals remain tight. Outdoor trays require additional checks for moisture accumulation and UV damage.

Summary

Proper installation of cable trays through walls involves: Using fire-rated penetration seals and backing platesSelecting appropriate tray materials and designs for airflow and heat dissipationEnsuring grounding, alignment, and mechanical integrityComplying with international fire safety standardsPerforming routine inspections and maintenance to maintain safety and functionality.