New National Standard Cable Tray

The latest national standard for cable trays is NEMA VE 1, harmonized with CSA C22. 2, covering metal and nonmetallic cable tray systems in accordance with NEC and CEC rules.

Overview of NEMA V

E 1NEMA VE 1 specifies manufacturing, design, and installation requirements for metal cable trays, including ladder, ventilated, solid bottom, channel, single-rail, and wire mesh types, along with associated fittings. It provides load/span class designations, guidance on shipping, handling, storing, installation, maintenance, and system modifications, ensuring compliance with the National Electrical Code (NEC) and the Canadian Electrical Code (CEC). This standard is harmonized with CSA C22.

2 Specification #126. 1, meaning it aligns with Canadian safety requirements without deviation.

Nonmetallic Cable Tray Standards

For fiberglass or other nonmetallic trays, NEMA FG-1 (now rescinded) and UL 568 define construction and performance requirements. These standards cover ladder, ventilated, solid bottom, and channel trays designed to support power or control cables safely.

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L 568 ensures that fiberglass trays meet performance and safety criteria for continuous systems.

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C 2023 UpdatesThe 2023 NEC Article 690. 31(C) introduces updated guidance for small conductors, such as PV wire and distributed generation cables, in cable trays. It clarifies ampacity calculations, conductor layering, tray sizing, and correction factors for different installation methods, aligning with broader NEC language like Article 392.

This update ensures safe and standardized use of smaller conductors in modern electrical installations.

International and Comparative Standards

For projects with international scope, IEC 61537 and BS EN 61537 provide global standards for metal and nonmetallic cable trays. Key differences include thickness specifications, corrosion classifications, and protective earth conductor use.

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A standards focus on load testing, while IEC/BS standards are more prescriptive with thickness tables and corrosion categories. Engineers should verify compliance with the applicable standard for their project location.

Material and Installation Considerations

Cable trays are manufactured from aluminum, steel, stainless steel, or fiberglass, with finishes such as pre-galvanized, hot-dip galvanized, or electro-galvanized to enhance corrosion resistance. Aluminum offers excellent corrosion resistance due to its natural oxide layer, while stainless steel alloys (e.g., AISI 316L) provide superior resistance in harsh environments. Proper tray selection depends on environmental conditions, load requirements, and cable types.

Practical Guidance

The Cable Tray Institute provides installation guidelines for aluminum and steel trays, including rung spacing, bend radius, and cable support. These guidelines are essential for engineers, contractors, and maintenance personnel to ensure safe, durable, and code-compliant installations. Periodic reviews of standards reflect advances in technology and construction techniques.

Key TakeawaysNEMA VE 1 is the primary national standard for metal cable trays, harmonized with CSA C22. 2.

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L 568 governs nonmetallic cable trays. 2023 NEC updates clarify small conductor use and ampacity calculations. Material selection and corrosion protection are critical for long-term performance.

International standards (IEC/BS) may differ in thickness and corrosion requirements, requiring careful specification for global projects. Following these standards ensures safe, reliable, and code-compliant cable tray installations across residential, commercial, and industrial applications.