Specifications of Fiberglass Cable Tray Supports

Fiberglass cable tray supports are governed by UL 568, IEC 61537, and NEMA FG-1 standards, specifying load, span, material, and fire-resistance requirements.

Key Standards

UL 568 defines performance requirements for fiberglass (nonmetallic) cable trays, including mechanical strength, electrical insulation, and safe application in industrial and commercial installations (Cable Tray Institute) . IEC 61537 is an international standard covering cable tray systems, including fiberglass trays, specifying load/span ratings, deflection limits, and testing procedures for safe support of power and control cables (Cable Tray Institute) . NEMA FG-1 (rescinded in 2017) historically provided manufacturing requirements for nonmetallic cable trays, including ladder, channel, and solid-bottom types, ensuring compliance with the National Electrical Code (NEC) . NFPA 70 (NEC) and CEC C22.1-Part 1 provide installation requirements, including ampacity considerations and proper support methods for cable trays in the U.S. and Canada, respectively .

Material and Construction Requirements

Fiberglass cable trays are typically pultruded, compression molded, or resin transfer molded, with glass fiber content between 45–65% by weight for pultruded components and 25–45% for molded components. All materials include UV inhibitors 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 .

Load and Span Guidelines

Manufacturers provide Safe Working Load (SWL) tables based on maximum deflection at mid-span for single-span installations. Span support criteria vary with tray depth (e.g., 2”, 3”, 5”, 7”, 9”) and are published in diagrams or tables per IEC 61537 . Continuous spans or different support points may allow higher load ratings.

Installation Considerations

Fiberglass trays must be installed according to NEC or CEC rules, ensuring proper support spacing, secure mounting, and allowance for thermal expansion. Manufacturer guidelines, such as those from Enduro Composites, provide detailed specifications for ladder-type fiberglass trays, including side rails, transverse rungs, and surfacing veils for chemical and UV protection .

Summary

For compliant fiberglass cable tray supports, reference UL 568 for performance, IEC 61537 for load/span and testing, and NEC/CEC for installation. Material composition, fire resistance, UV protection, and manufacturer SWL tables are critical for safe and durable installations .