Construction Requirements for Fiberglass Cable Trays

Fiberglass cable trays must meet specific material, structural, fire, UV, and installation standards, including compliance with UL 568, NEMA FG-1, NEC, and IEC 61537.

Material and Manufacturing Requirements

Fiberglass cable trays are typically manufactured using pultrusion, compression molding, or resin transfer molding, with a glass fiber to resin content of 45–65% by weight for pultruded components and 25–45% for molded components . All materials must include UV inhibitors to resist degradation and be fire retardant, achieving a Class 1 flame spread rating (≤25) per ASTM E-84 . Pultruded polyester and vinyl ester trays should have a complete surfacing veil for chemical and UV protection, and conductive resin systems may include carbon additives to dissipate static electricity .

Structural and Load Requirements

Fiberglass trays must be designed according to Safe Working Load (SWL) and span criteria as per IEC 61537, with load vs. span tables or diagrams provided by the manufacturer . Typical nominal tray depths range from 2” to 9” (51–229 mm), and rung spacing of 6–9 inches (150–230 mm) is recommended for ladder-type trays . Continuous spans and deflection measurements should be considered to ensure structural integrity under load .

Installation Guidelines

• Cutting and Drilling: Use a circular saw with an abrasive wheel or hack saw; drill with standard twist drills. All cut or drilled surfaces must be sealed with compatible resin .
• Support: Tray sections should be equal to or greater than the support span, with splices ideally at quarter span. Trapeze supports should not exceed the distance between splice plates .
• Fastening: Thread rod nuts require 3–4 ft.-lbs. torque, and all-thread rods must be fully engaged in clamps such as B-Line BFPU751 series .
• Spacing: Maintain a maximum 2” distance between supported material and rod to ensure proper load distribution .

Compliance with Codes and Standards

Fiberglass cable trays must comply with:

• UL 568: Performance and safety requirements for fiberglass trays .
• NEMA FG-1: Manufacturing and installation standards for nonmetallic trays .
• NEC (NFPA 70): Installation requirements, including ampacity and conductor fill (Articles 310 and 318), .
• IEC 61537: International standard for cable tray systems, including load and span testing .
• CEC C22.1-Part 1: Canadian Electrical Code requirements for installation and maintenance .

Additional Considerations

• Fire and UV Protection: Ensure all trays are fire retardant and UV-stable for outdoor or exposed applications .
• Chemical Resistance: Pultruded trays should have a surfacing veil to resist chemical exposure .
• Static Dissipation: Conductive trays may include carbon additives to prevent static buildup .
• Cable Fill and Segregation: Follow NEC guidelines for power, control, and signaling circuits, ensuring proper separation and fill ratios . By adhering to these construction, material, and installation requirements, fiberglass cable trays provide durable, safe, and code-compliant support for electrical and control cables in industrial, commercial, and marine environments.