If you have worked on international electrical tender packages, you know standard compliance can make or break an approval. Many engineers and procurement teams reach out to BDCABLETRAY late in the quoting stage, only to realise they mixed IEC and NEMA requirements. This often delays test report preparation and pushes back delivery timelines. This guide breaks down what each standard covers, where they apply, and what you should write directly on your specification sheet.
Core IEC standard for cable tray systems
IEC 61537 is the main global reference for cable tray and cable ladder systems. The 2023 edition is the most current version, and it applies to metal, FRP, wire mesh and perforated tray assemblies used for power, control and data cables.
What IEC 61537 actually tests
This standard focuses on system-level performance, not just the tray body. It lays out test routines for uniform load, mid-span deflection, impact resistance, electrical continuity and ageing. Fittings such as splice plates, brackets, hangers and cover clips must be included in the test assembly. A tray that passes the test alone may fail once paired with weak accessories.
How IEC handles load rating and deflection
Unlike NEMA, IEC 61537 does not use preset letter classes. Manufacturers declare a safe working load at a defined support span, with deflection capped at span/100. The safety factor is clearly defined, and every rated value must be backed by third-party test records.
Installation and cable derating sit outside IEC 61537. Fill ratio and current derating for grouped cables are covered in IEC 60364, so you cannot rely only on the tray standard for thermal design.
Core NEMA standards for North American cable tray
NEMA standards dominate US and Canadian projects, paired with NEC Article 392. The most referenced documents are NEMA VE 1 for metal trays and NEMA FG 1 for fiberglass FRP trays.
NEMA VE 1 for metal cable tray construction
NEMA VE 1 uses a familiar class-based rating system. Class A through D defines load capacity at standard imperial spans. This format is easy for local contractors and inspectors to read, which is why it remains the default for most North American commercial and industrial builds. It covers material thickness, edge forming, bonding paths and factory inspection rules.
NEMA FG 1 for FRP non-metallic trays
When FRP trays are specified for corrosive environments, NEMA FG 1 is the standard to call out. It addresses UV stability, flame performance and long-term creep that matters for chemical plants, coastal sites and wastewater facilities.
NEMA installation and bonding guidance
NEMA also publishes installation guidance that covers storage, field assembly, support spacing and equipment bonding. Metal cable trays under NEMA rules are commonly accepted as an equipment grounding path when assembled correctly, which is a key difference from IEC practice.
Key practical differences between IEC 61537 and NEMA VE 1
Load classification method is the biggest gap. NEMA uses fixed letter classes, while IEC uses performance-based SWL declarations. You cannot convert a NEMA class directly into an IEC rating, even if the tray looks similar.
Earthing and bonding logic differs a lot. NEMA accepts properly installed metal trays as a bonding conductor in many NEC applications. IEC 61537 only tests electrical continuity; it does not automatically qualify the tray as an earthing route. The earthing design must be checked against local wiring codes separately.
Regional acceptance also splits clearly. IEC 61537 is widely accepted for EPC projects across the Middle East, Southeast Asia, Africa and Europe. NEMA VE 1 and FG 1 are mainly for USA and Canada, and many local inspectors will ask for NEMA marking and supporting certificates.
How to specify cable tray standards correctly on your project
Start with the governing electrical code of the project country. If it is an international EPC tender, IEC 61537 is the usual baseline. If the site is in the US or Canada, specify NEMA VE 1 or NEMA FG 1 alongside NEC requirements.
List fittings in your standard clause. A common mistake is specifying the tray body only and forgetting splices, brackets and accessories. The whole system must comply with the same standard.
Ask for documents early. At BDCABLETRAY, our technical team reviews tender specs before production starts. We can arrange third-party test reports, material certificates and product marking to match your required standard.
Common specification mistakes to avoid
Do not assume one standard covers the other. Some buyers ask for IEC trays and then expect NEMA class stamps, which will not be available unless dual testing is arranged.
Do not mix product standards with site codes. IEC 61537 and NEMA VE 1 are product performance standards. They do not replace hazardous area rules, fire codes or local installation regulations such as ATEX or NEC hazardous location sections.
Do not overlook corrosion and environmental tests. Coastal, chemical and underground projects need extra coating, UV or chemical resistance tests that sit outside the base mechanical load tests.
If you need cable trays manufactured and documented to IEC 61537, NEMA VE 1 or NEMA FG 1 for your next tender, contact BDCABLETRAY. Our team can sort out test documentation and standard compliance details to help your project pass inspection smoothly.
FAQ
Can one cable tray design be certified to both IEC 61537 and NEMA VE 1?
It is possible if the manufacturer runs separate test sequences and provides two independent sets of reports. Still, the ratings are not interchangeable, and your project specification must clearly state which standard will be used for acceptance.
Does IEC 61537 apply to wire mesh cable tray?
Yes. The latest IEC 61537:2023 covers wire mesh, perforated, solid-bottom, ladder and FRP cable tray systems, as long as the full assembly including fittings is tested as one system.
Is NEMA VE 1 a legal requirement for all cable trays sold in the USA? It is not a standalone law, but most engineering specifications and electrical inspectors require NEMA VE 1 compliance plus NEC Article 392 for commercial and industrial cable tray installations.
What documents should I collect to verify IEC or NEMA compliance?
You will need third-party test reports covering load, deflection, impact and continuity. Certificates of conformity and clear product marking records are also often required for tender and site submission packages.
Which standard should I pick for an EPC project in Southeast Asia?
Most cross-border EPC projects in Southeast Asia adopt IEC 61537 as the cable tray product standard, paired with local wiring codes. Always cross-check the project specification before locking in your supplier’s test scope.