Fire protection and low-voltage wiring cable trays

Fire-resistant cable trays are essential for safely routing low-voltage electrical wiring in high-risk environments, combining material selection, proper installation, and firestopping measures.

Cable Tray Material Selection

Choosing the right material is critical for fire safety. Steel, aluminum, and fiber-reinforced plastics are commonly used, but their fire performance varies. Steel trays, especially fire-coated steel, provide excellent structural integrity and reduce fire spread, making them suitable for high-risk areas like data centers, hospitals, and high-rise buildings.

Aluminum is lightweight and corrosion-resistant but less fire-resistant, while stainless steel offers strength and corrosion protection but does not inherently prevent fire propagation. Fire-resistant cable trays, such as Cablofil FP trays, have been tested to withstand temperatures up to 1000°C for 30–90 minutes according to DIN 4102-12 standards.

Layout and Installation Principles

Proper tray layout enhances both electrical performance and fire safety. Key guidelines include: Route Planning: Align trays with the building structure, avoiding unnecessary crossings or detours. Segregation: Separate low-voltage (signal) and high-voltage power cables to minimize interference and fire risk.

Tray Type and Strength: Select tray width and thickness based on cable weight and quantity, ensuring mechanical strength to prevent deformation under load. Installation Accuracy: Maintain horizontal deviation ≤2mm/m and vertical deviation ≤3mm/m; trays must be level, plumb, and securely mounted.

Firestopping Measures

Where cable trays penetrate walls, floors, or slabs, firestopping is mandatory to maintain compartmentalization and prevent fire spread. Key practices include: Seal openings with fire-rated boards, firestop packs, firestop mastic, or mineral wool. Ensure gaps around cables do not exceed 1 cm² and packing thickness is at least 24 cm.

For large openings, install a fire-resistant backing plate before sealing. Cover plates should be square, consistent, and painted evenly to maintain integrity.

Best Practices

Use fire-resistant cable cleats to secure cables within trays, preserving tray integrity during fire exposure. In high-risk environments, prioritize fire-coated steel trays or certified fireproof systems. Regularly inspect and maintain trays and firestopping to ensure ongoing compliance with fire safety standards.

By combining appropriate materials, careful layout, and robust firestopping, low-voltage cable trays can maintain electrical functionality while minimizing fire hazards, protecting both equipment and building occupants.