Fire protection requirements for cable trays in power distribution rooms

Cable trays in power distribution rooms must be equipped with fire-blocking sections, firestopping materials, and proper installation practices to prevent fire spread and ensure system safety.

Fire-Blocking Sections and Purpose

Fire-blocking sections, also called fire partitions, are installed along cable trays to isolate potential fire sources, prevent fire propagation, and protect power system stability. These sections are critical in high-risk environments such as power distribution rooms, cable trenches, tunnels, and overhead bridges leading to control rooms or distribution devices. They also enhance the disaster resistance of power facilities and reduce potential casualties and property losses .

Firestopping Materials

Common firestopping materials for cable trays include:

• Fire-rated boards and fireproof coatings for walls and slab penetrations
• Firestop packs and firestop mastic for sealing gaps around cables and trays
• Fire-resistant mineral wool for large openings or high-temperature areas
• Intumescent caulks (e.g., IC 15WB) and 3M fire barrier pillows for through-penetrations Materials should be stable under environmental conditions, resistant to water immersion, corrosion, and rodent damage, and maintain fire resistance over time .

Installation Requirements

• Sealing: All openings around cable trays, busways, and conduits must be tightly sealed without visible cracks or voids. Gaps between firestop packs and cables should not exceed 1 cm², and packing thickness should be at least 24 cm .
• Slab Penetrations: Provide 20–30 mm of firestopping at slab penetrations and install a fire-support plate at the top. Waterstops of at least 50 mm height are recommended at floor-level penetrations .
• Layout: Fire-blocking sections should be positioned to facilitate installation, maintenance, and cable routing. Cover plates should be square, evenly painted, and properly dimensioned .
• UL Ratings: Use UL-listed firestop systems appropriate for the wall or slab type, e.g., concrete walls with 3-hour F-rating or gypsum walls with 1–2 hour F-ratings .

Maintenance and Durability

Fire-blocking sections and firestopping materials must be durable, corrosion-resistant, and maintain performance over the service life of the installation. Regular inspections and maintenance are recommended to ensure continued fire protection, especially in high-risk industrial environments .

Additional Considerations

• Segregation: Power and signal cables should be routed separately to reduce fire and electrical interference risks .
• Mechanical Integrity: Cable trays must be securely mounted, level, and plumb, with proper grounding and splice plates to maintain electrical continuity .
• Environmental Compliance: Materials should meet environmental protection standards and minimize impact on the surrounding environment . By following these fire protection requirements, power distribution rooms can achieve enhanced safety, compliance with fire codes, and reliable operation of electrical systems.