Cable trays must be sealed with fire-resistant materials both internally and externally, using approved firestopping systems and coatings to prevent fire spread and maintain safety.

Indoor Fireproof Sealing

Material Selection: Use fire-rated boards, firestop packs, firestop mastic, or fire-resistant mineral wool to seal gaps around cables and trays inside walls, floors, and slabs. Firestop packs should be installed in an orderly sequence, with gaps between packs and cables not exceeding 1 cm² and a minimum packing thickness of 24 cm. Large openings require a fire-resistant backing plate before sealing, and cover plates should be square, evenly painted, and securely fixed . Installation Requirements: Ensure all gaps inside and around metal trunking or cable trays are tightly sealed without visible cracks or voids. Electrical shafts should have thresholds, and slab penetrations should include 20–30 mm of firestopping with a fire-support plate at the top. Waterstops of at least 50 mm height are recommended at floor-level penetrations . Inspection and Maintenance: Periodically inspect fireproof trays for coating integrity, cracks, or voids. Ensure that firestop materials remain intact and that all seals are complete both internally and externally .

Outdoor Fireproof Sealing

Tray Material and Coating: Use hot-dip galvanized or stainless steel trays for outdoor installations. Apply fireproof coatings that comply with national safety standards, ensuring uniform thickness and adhesion. Coatings should resist UV, moisture, and corrosion while preventing flame propagation . Sealing Methods: Fire protection tapes or coatings, such as FLAMMOTECT-A or DG-CR 0.7, can be applied around cables and trays to form a protective shield. Ensure that all joints, penetrations, and tray edges are sealed to prevent fire spread and environmental damage . Inspection: Regularly check outdoor trays for rust, moisture accumulation, or coating degradation. Verify that fireproof coatings maintain their thickness and adhesion according to design specifications .

Modular Firestop Solutions

For both indoor and outdoor applications, modular sealing systems like Roxtec can be used to protect cable penetrations. These systems allow for flexible installation, easy addition or replacement of cables, and maintain fire ratings while also providing protection against water, gas, and other hazards .

Key Takeaways

• Seal all gaps around cable trays and penetrations with approved firestop materials.
• Use fire-resistant coatings for both indoor and outdoor trays to prevent flame propagation.
• Install backing plates and cover plates for large openings to ensure complete sealing.
• Regular inspection and maintenance are essential to maintain fireproof integrity.
• Modular systems provide flexibility for future cable changes while maintaining fire safety. By following these requirements, cable tray installations will comply with fire safety standards, prevent fire spread, and ensure reliable operation of electrical systems in both indoor and outdoor environments.