Power cable trays in factory buildings must be installed with fire-resistant materials, proper spacing, ventilation, and firestopping measures to prevent fire spread and ensure compliance with safety standards.

Material Selection and Tray Design

Cable trays should be made of fire-resistant materials such as hot-dip galvanized steel or stainless steel for indoor and outdoor use, or aluminum alloy/fiberglass-reinforced plastic in corrosive or high-humidity environments . The tray must support the weight of cables without deformation and allow proper airflow to prevent overheating. Perforated or wire mesh trays are recommended to improve ventilation and heat dissipation, reducing the risk of insulation damage and fire .

Installation and Layout

• Segregation of cables: High-voltage power cables should be separated from low-voltage or signal cables to minimize electromagnetic interference and reduce fire risk .
• Support intervals: Trays must be supported at regular intervals (typically 2–3 meters for normal spans, up to 6 meters for long spans) to maintain structural integrity .
• Load capacity: Ensure trays are not overloaded; follow manufacturer specifications and NEC Section 392 guidelines for cable fill and spacing .
• Ventilation: Proper spacing and perforation allow heat dissipation, preventing overheating and reducing fire hazards .

Firestopping and Penetrations

Where cable trays pass through walls, floors, or slabs, openings must be sealed with firestopping materials such as fire-rated boards, firestop packs, firestop mastic, or fire-resistant mineral wool . Key requirements include:

• Tight sealing: No visible cracks or voids; gaps around cables should not exceed 1 cm² .
• Packing thickness: Minimum 24 cm for firestop packs .
• Fire-support plates: Install at slab penetrations and large openings to maintain fire compartmentalization .
• Waterstops: At floor-level penetrations, provide at least 50 mm height to prevent water ingress .
• Cover plates: Must be square, consistent in size, and painted evenly to close openings .

Fire Safety Practices

• Cable organization: Use separators, covers, and clamps to prevent overcrowding and improve airflow .
• Preventive maintenance: Regular inspection for damaged insulation, loose connections, or overheating is essential to reduce fire risk .
• Fire-rated accessories: Use fire-rated cable ties in plenum spaces to avoid toxic smoke emission during a fire .
• Compliance: Follow NEC, NFPA, IEC, and local standards to ensure the cable tray system meets approved fire safety requirements .

Summary

To ensure fire protection in factory buildings, power cable trays must combine fire-resistant materials, proper installation, ventilation, segregation, and firestopping measures. Regular maintenance and adherence to standards such as NEC Article 392, NEMA guidelines, and NFPA codes are critical to prevent fire hazards, protect equipment, and maintain operational safety .