Standards for Laying Fiberglass Cable Trays

Fiberglass cable trays must comply with UL 568, NEMA FG-1, and NEC Article 392 standards, ensuring proper material, load capacity, installation, and safety.

Key Standards and Codes

UL 568 specifies performance requirements for fiberglass cable trays, including mechanical strength, fire resistance, and environmental durability, ensuring safe application in industrial and commercial installations (Cable Tray Institute) . NEMA FG-1 (now rescinded but historically referenced) outlined manufacturing requirements for nonmetallic cable trays, including ladder, ventilated, solid-bottom, and channel types, in accordance with the National Electrical Code (NEC) . NEC Article 392 governs cable tray systems, including fiberglass trays, covering installation, tray fill limits, grounding, bonding, and separation of power and data cables to prevent interference and ensure safety . IEC 61537 provides international requirements and testing for both metallic and nonmetallic cable trays, including load, span, and environmental performance .

Material and Environmental Considerations

Fiberglass-reinforced plastic (FRP) trays are preferred in corrosive or high-humidity environments due to their superior corrosion resistance and high strength-to-weight ratio . Indoor installations may use painted steel or galvanized trays, while outdoor or corrosive environments require FRP or aluminum alloy trays .

Installation Guidelines

• Tray Layout: Follow the shortest and straightest path, avoiding unnecessary crossings or detours. Segregate power and signal cables to minimize electromagnetic interference .
• Support and Mounting: Ensure trays are level, plumb, and securely mounted. Horizontal deviation should not exceed 2 mm per meter, and vertical deviation should not exceed 3 mm per meter .
• Rung Spacing: For ladder-type fiberglass trays, a rung spacing of 150–230 mm (6–9 inches) is recommended to support cables without sagging .
• Load and Span: Select tray width, thickness, and support spacing according to the number, weight, and type of cables to prevent deformation or failure under full load .
• Fire and Safety: Use trays with appropriate fire ratings and ensure compliance with NFPA 70E for electrical hazard protection .

Additional Considerations

• Cable Fill: Do not exceed tray fill limits to prevent overheating and maintain airflow .
• Grounding: While FRP trays are nonmetallic, any metallic fittings or supports must be properly grounded if required by local codes .
• Maintenance: Periodically inspect trays for mechanical integrity, corrosion, and proper cable support . By adhering to these standards and guidelines, fiberglass cable tray installations can achieve long-term reliability, safety, and compliance with electrical codes and industry best practices.