Methods for sealing cables laid inside cable trays

Cables in cable trays can be effectively sealed using firestop systems, modular sealing plugs, GRP sealants, and compressible tray inlays to ensure fire safety, weatherproofing, and maintainability.

Firestop and Penetration Sealing

For cable trays passing through walls, floors, or slabs, firestopping is essential to prevent the spread of fire and smoke. Openings should be tightly sealed using fire-rated boards, firestop packs, firestop mastic, or mineral wool, ensuring no visible cracks or voids remain. Large openings may require a fire-resistant backing plate before sealing, and gaps around cables should be minimal, typically not exceeding 1 cm², with packing thickness of at least 24 cm for effective protection.

Cover plates should be square, consistent, and painted evenly to maintain integrity and aesthetics.

Modular and Replaceable Sealing Systems

Modern solutions include modular sealing systems that allow easy installation and future cable additions. For example, a tray inlay with a replaceable cover can seal cables while leaving space for new cables to be added without removing the entire seal. Compressible seal portions in the inlay and cover enclose the cables securely, providing both fire and smoke protection while maintaining flexibility for maintenance or expansion.

Weatherproofing and Environmental Protection

For cable trays exposed to external conditions, weatherproofing is critical. Systems such as GRP (glass-reinforced plastic) sealants or weatherstop sealing systems can protect against water, wind, and pests. Roof penetrations may use service risers and upstands to create a structurally sound, waterproof seal, while wall penetrations can employ GRP weathering systems that adapt to various shapes and sizes of cable trays.

Proprietary Sealing Plugs and Inserts

Specialized products like SLIPSIL sealing plugs, RISE® expanding rubber sleeves, and NOFIRNO gaskets provide fire-safe, gas-tight, and watertight seals for single or multiple cables. These systems often feature self-compression designs without metallic parts, reducing corrosion risk and maintenance needs. Modular systems like FIRSTO firestops or DYNATITE can be installed around existing cables, ensuring tightness and fire protection even in critical applications.

Best Practices

Classify cables by type and function to optimize space and prevent overcrowding in trays. Ensure proper installation sequence, including grounding, waterproofing, and firestopping. Select materials compatible with the building's fire rating and environmental exposure.

Allow for future maintenance, using modular or replaceable systems to avoid dismantling existing seals. By combining fire-rated materials, modular sealing systems, and weatherproofing techniques, cable trays can be effectively sealed to maintain safety, environmental protection, and operational flexibility.