What are the specifications for fiberglass cable trays

Fiberglass cable trays are manufactured and installed according to NEMA FG 1, UL 568, and IEC 61537 standards, with specific material, load, and fire-resistance requirements.

Material and Construction

Fiberglass cable trays are typically made from pultruded, compression molded, or resin transfer molded fiberglass reinforced plastic (FRP). The glass fiber content is maintained between 45–65% by weight for pultruded components and 25–45% for molded components, with flat sheets at 35–45% glass content. All materials include UV inhibitors to resist degradation and are fire retardant, achieving a Class 1 flame spread rating (≤25) per ASTM E-84. Conductive resin systems may include carbon additives to dissipate static electricity, particularly for marine or industrial applications (Enduro Composites specifications) .

Load and Safety Requirements

Fiberglass trays must meet Safe Working Load (SWL) requirements as per IEC 61537, with load vs. span ratings based on maximum deflection at mid-span. A safety factor of 1.5 is standard, ensuring the tray can support 1.5 times the allowable working load. Straight ladder-type trays consist of two longitudinal side rails connected by transverse rungs, with rung spacing typically 6–9 inches for instrumentation and control applications .

Standards and Compliance

• NEMA FG 1: Specifies manufacturing requirements for nonmetallic cable trays, including ladder, channel, ventilated, and solid-bottom types, in accordance with the National Electrical Code (NEC) .
• UL 568: Covers performance requirements for safe application of fiberglass cable trays, including mechanical strength and fire resistance .
• IEC 61537: International standard for cable tray systems, defining load, span, and testing requirements for both metallic and nonmetallic trays .
• NFPA 70 (NEC): Provides installation requirements, including ampacity considerations and conductor placement in cable trays .
• ABS Approval: For marine and harsh environments, fiberglass trays may comply with American Bureau of Shipping (ABS) rules, ensuring suitability for caustic, marine, and industrial conditions .

Design Features

Fiberglass trays are available in ladder, channel, and solid-bottom configurations, with options for flange-in or flange-out siderail profiles. They can be pre-drilled for splice plate fasteners, and some designs allow fiberglass struts as alternating rungs for easier cable loading. Rung designs provide a 2-inch cable support surface, and mitered fittings with a 12-inch radius are standard for smooth cable transitions .

Environmental and Fire Considerations

Fiberglass trays are ideal for chemical, petrochemical, industrial, and marine environments due to their corrosion resistance, UV stability, and fire retardancy. Polyester or vinyl ester resins are commonly used, with a complete surfacing veil to maximize chemical and UV protection. These trays are suitable for vertical installations and harsh environmental conditions .

Summary

Fiberglass cable trays are engineered to meet strict material, load, and fire safety standards, including NEMA FG 1, UL 568, IEC 61537, and NEC compliance. They are designed for durability, corrosion resistance, and safe cable support in industrial, marine, and chemical environments, with standardized rung spacing, safety factors, and installation guidelines to ensure reliable performance.