Fireproof cable trays for low-voltage cables require proper material selection, fire-resistant barriers, secure installation, and adherence to standards like DIN 4102-12 to ensure safety and reliability.

Material Selection and Tray Types

For indoor low-voltage cable installations, painted steel or galvanized steel trays are commonly used, while hot-dip galvanized or stainless steel trays are preferred for outdoor environments. In corrosive or high-humidity areas, aluminum alloy or fiberglass-reinforced plastic trays are recommended. The tray width and thickness must be selected based on the number and weight of cables, ensuring sufficient mechanical strength to prevent deformation under full load . Fireproof cable trays, such as Cablofil systems, are tested to withstand temperatures up to 1000°C for 30, 60, and 90 minutes according to DIN 4102-12 standards .

Fireproofing Measures

Fireproofing involves multiple layers of protection:

• Reserved Openings: Openings for cable trays should exceed the tray dimensions by at least 100mm to allow effective sealing .
• Steel Protective Plates: Use 4mm thick steel plates, extended by 200mm beyond tray dimensions, treated with anti-rust paint and fireproof coating .
• Fire Blocking Materials: Place fire-resistant boards, mineral wool, or firestop packs layer by layer, ensuring dense and compact barriers .
• Fireproof Mortar: Fill gaps between cables, trays, and fire-blocking materials with fireproof mortar, applied evenly to maintain both sealing integrity and aesthetic finish .
• Firestop Caulks and Putty: Products like 3M Fire Barrier Moldable Putty+ or intumescent caulks can seal penetrations and prevent heat transfer to structural steel .

Installation Guidelines

• Alignment and Support: Trays must be level, plumb, and securely mounted. Horizontal deviation should not exceed 2mm per meter, and vertical deviation should not exceed 3mm per meter .
• Segregation: Low-voltage cables should be routed separately from high-voltage or signal cables to minimize interference .
• Water Stop Platforms: In vertical shafts, construct smooth water stop platforms to facilitate sealing and fireproofing .
• Cover Plates: Ensure cover plates are square, evenly painted, and securely fixed to maintain fire protection .

Standards and Testing

Fireproof cable trays should comply with recognized standards such as DIN 4102-12, which tests the tray system in an oven for high-temperature exposure. Proper installation ensures that the system can contain fire and smoke, protecting both the cables and surrounding structures .

Quality Control

• Verify opening sizes and tray alignment before installation.
• Ensure fireproof materials are densely packed without gaps.
• Confirm steel plates and boards are properly treated and fixed.
• Inspect the evenness of fireproof mortar and caulking to prevent weak points . By following these guidelines, low-voltage cable trays can achieve optimal fire resistance and retardation, ensuring safety, compliance, and long-term reliability in industrial and commercial installations.