FRP Cable Tray Standards: IEC 61537, UL 568 and Why NEMA FG-1 Is Rescinded

In short: FRP cable tray is covered by two main product standards. IEC 61537 is the international standard for cable tray and cable ladder systems, metal and non-metallic. UL 568, published jointly with CSA C22.2 No. 126.2, covers nonmetallic cable tray for use under the US National Electrical Code (NEC) and the Canadian Electrical Code. NEMA FG-1, the old US fiberglass cable tray standard, was rescinded in November 2017, so specifications that still cite it should be updated. Installation in the US follows NEC Article 392. FIBROVX makes FRP cable trays and supports to order. Width, height, length, resin, color and covers can all be customized to your project specification.

Why standards matter for FRP cable tray

A cable tray is a structural support for electrical cables. A good standard does three jobs for the buyer:

• It defines how load capacity is tested, so two suppliers' numbers can be compared.
• It sets safety requirements, such as flame behavior and electrical properties.
• It gives a common language for the specification, the drawing and the inspection.

FRP trays are popular in chemical plants, wastewater plants, offshore and coastal sites, mines and cooling towers, because they do not rust and do not conduct electricity. These are also the sites where specifications are strict, so it pays to cite the right documents.

The standards at a glance

Two kinds of documents appear in this table. Product standards describe how the tray is built and tested. Installation codes describe where and how trays may be used. A complete specification usually needs one of each.

IEC 61537: the international standard

IEC 61537, Cable management – Cable tray systems and cable ladder systems, applies to tray and ladder systems that support and hold cables in electrical and communication installations. It covers metal, non-metallic and composite components, so FRP trays are in scope. It does not apply to conduit, cable trunking or cable ducting.

The current third edition was published in January 2023 and replaced the 2006 second edition. According to IEC, the main technical changes include:

• revised safe working load (SWL) test types and procedures;
• new tests for lengths mounted vertically;
• tests for support devices such as cantilevers, pendants, C-shaped ceiling supports and trapeze systems;
• a revised classification for corrosion.

Safe working load

The key structural number in IEC 61537 is the safe working load (SWL): the maximum load that can be applied safely in normal use. It is tested as a uniformly distributed load over a stated span. Under SWL, the deflection at mid-span is commonly limited to 1/100 of the span, and the tray must show no visible damage or cracking. For example, on a 2,000 mm (about 6.6 ft) span, 1/100 of the span is 20 mm (about 0.8 in).

This matters for FRP. Glass-fiber composites are strong but less stiff than steel, so for many FRP trays the deflection limit, not breaking strength, sets the SWL. Always compare SWL values at the same span.

Classification

IEC 61537 also asks the manufacturer to declare a classification. The headings include the material type, resistance to flame propagation, electrical continuity and conductivity, impact resistance and the temperature range. For FRP, the useful items to ask about are:

• non-flame propagating behavior, which depends on the resin and fire-retardant additives;
• non-conductive behavior, which is a natural property of glass-fiber composites;
• the declared minimum and maximum temperatures for transport, installation and use.

UL 568 and CSA C22.2 No. 126.2: North America

UL 568, Nonmetallic Cable Tray Systems, specifies requirements for nonmetallic cable trays and fittings designed for use under the NEC and the Canadian Electrical Code. It was developed as a binational standard with CSA C22.2 No. 126.2, and the CANENA committee scope states that the work was based on NEMA FG-1. The first edition of UL 568 is dated October 15, 2002. UL Standards & Engagement reaffirmed it as an American National Standard on November 29, 2023, with no technical changes.

If your project is in the US or Canada and the engineer asks for a "listed" nonmetallic tray, UL 568 or CSA C22.2 No. 126.2 is usually the reference. A listing is granted by a testing laboratory to a specific product line. It is not something the buyer can create later, so ask about it at the quotation stage.

NEMA FG-1: what "rescinded" means

NEMA FG-1, Fiberglass Cable Tray Systems, covered construction and testing of fiberglass ladder, ventilated trough, solid bottom and channel trays. The Cable Tray Institute notes that NEMA rescinded FG-1 as a published standard in November 2017.

Rescinded means NEMA no longer publishes or maintains the document. It does not mean older trays built to it are unsafe. But it does mean:

• new specifications should not cite FG-1 as the governing standard;
• if an existing specification cites FG-1, ask the engineer whether UL 568, CSA C22.2 No. 126.2 or IEC 61537 should replace it;
• old FG-1 load class tables can still be useful as a reference for comparison, but the project should state which document governs.

Many older specifications describe trays with span and load class designations borrowed from NEMA practice, such as a span in feet plus a letter for the load class. If you see these, convert them into plain numbers: the support span and the working load per unit length. That makes quotations easier to compare across standards.

NEC Article 392: installation in the US

The NEC (NFPA 70) does not tell you how to make a tray. Article 392 tells you where cable trays may be used and how to install them, including cable types, cable fill, support, grounding and bonding. Article 392 permits nonmetallic cable tray in corrosive areas and in areas that require voltage isolation, which are the places FRP is chosen most often.

Two practical points follow from FRP being non-conductive:

• An FRP tray cannot serve as an equipment grounding conductor. Plan a separate grounding conductor where the design needs one.
• Metal fittings and bolts used with the tray must be grounded and bonded as the code requires.

Local authorities adopt different NEC editions, so confirm which edition applies.

Other documents you may see

• NEMA VE 1 and VE 2. VE 1 covers metal cable tray and does not apply to FRP. VE 2 is an installation guideline for cable tray and is often referenced for good practice.
• ASTM E84. A surface-burning test often used in specifications to set a flame spread limit for the FRP. See our guide to FRP grating fire ratings and ASTM E84 for how the test works.
• Project specifications. Oil and gas, power and mining owners often have their own specifications that add requirements on top of IEC 61537 or UL 568.

How to write a clear FRP cable tray specification

A clear specification saves time at quotation and inspection. State:

1. Governing standard. IEC 61537, UL 568 or CSA C22.2 No. 126.2. Do not cite NEMA FG-1 alone.
2. Tray type. Ladder, ventilated (perforated) or solid bottom. Our guide to ladder vs perforated vs solid bottom cable tray explains the choice.
3. Load and span. The working load per unit length, the support span, and any concentrated, snow, ice or wind loads. See FRP cable tray load and span selection.
4. Size. Inside width, side rail height and section length.
5. Resin. General-purpose polyester, isophthalic or vinyl ester, depending on the chemicals present. Our chemical resistance guide can help.
6. Flame behavior. Fire-retardant resin and the test method you need.
7. Outdoor use. UV-resistant surface veil or coating.
8. Temperature range. Maximum service temperature affects the resin and the load rating.
9. Covers and fittings. Elbows, tees, reducers, splice plates, covers and hardware material.
10. Documents. Drawings, load test data for the tray family, material data and inspection reports.

How FIBROVX can help

FIBROVX makes FRP cable trays and FRP cable supports in our own factory. Every tray can be customized: width, side height, length, bottom type, resin system, color, UV protection and covers. Tell us which standard governs your project and the load and span you need, and we will propose a matching section and the supporting test data we can provide for it. We do not claim certifications we do not hold, so we will tell you clearly what documents are available for each product.

Browse the full range in Cable Trays & Supports, or read the FRP cable tray guide for an overview.

Key terms

• Span: The distance between the centers of two adjacent supports.
• Uniformly distributed load (UDL): Load spread evenly along the tray.
• Rescinded: Withdrawn by the publisher and no longer maintained.
• Listing: A testing laboratory's record that a specific product meets a standard.

FAQ

Is NEMA FG-1 still valid?

NEMA rescinded FG-1 as a published standard in November 2017. New specifications should cite UL 568, CSA C22.2 No. 126.2 or IEC 61537 instead.

What replaced NEMA FG-1?

In North America, UL 568 and the harmonized CSA C22.2 No. 126.2 cover nonmetallic cable tray. The CANENA committee scope states that this binational standard was based on NEMA FG-1.

Does IEC 61537 apply to FRP cable tray?

Yes. IEC 61537 covers metal, non-metallic and composite cable tray and cable ladder systems.

Can FRP cable tray be used as a grounding conductor?

No. FRP does not conduct electricity, so a separate grounding conductor is needed where the design requires one.

Is FRP cable tray allowed under the NEC?

NEC Article 392 permits nonmetallic cable tray in corrosive areas and in areas that require voltage isolation, subject to the rest of the article and local adoption.

Related guides

• FRP Cable Tray Guide
• FRP Cable Tray Load and Span Selection
• Ladder vs Perforated vs Solid Bottom Cable Tray
• Custom FRP Manufacturing
• Industries we serve

Sources

• IEC 61537:2023, Cable management – Cable tray systems and cable ladder systems: https://webstore.iec.ch/en/publication/31963
• UL 568, Nonmetallic Cable Tray Systems (UL Standards & Engagement): https://www.shopulstandards.com/ProductDetail.aspx?UniqueKey=8835
• Cable Tray Institute, Codes and Standards (NEMA FG-1 rescinded November 2017): https://www.cabletrays.org/codes-and-standards/
• CANENA THC 23A-2, Nonmetallic Cable Trays (UL 568 / CSA C22.2 No. 126.2 scope): https://www.canena.org/standards-development/committees/thc-23a-2-nmct-nonmetallic-cable-trays/
• CSA Informs, CSA C22.2 No. 126.2-02 Nonmetallic Cable Tray Systems: https://www.csagroup.org/wp-content/uploads/CableTraySystems06A.pdf
• NFPA 70, National Electrical Code: https://www.nfpa.org/codes-and-standards/nfpa-70-standard-development/70