Standard for Welding Trays in Low Voltage Electrical Rooms

Metallic cable trays in low voltage electrical rooms should comply with NEMA VE-1 or equivalent IEC standards, with materials and fabrication meeting ASTM and BS EN specifications.

Applicable Standards

NEMA VE-1 / IEC Standards Metallic cable trays are typically manufactured in accordance with NEMA VE-1 or equivalent IEC standards, which define the mechanical, electrical, and environmental requirements for cable tray systems used in low voltage installations . These standards ensure structural integrity, proper load-bearing capacity, and safe routing of electrical cables. ASTM Specifications For welded steel trays, the following ASTM standards are commonly applied:

• ASTM A123 – Hot-dip galvanized coatings on steel products
• ASTM A653 – Zinc-coated (galvanized) steel sheet, structural quality
• ASTM A1011 / A1008 – Hot-rolled and cold-rolled carbon steel sheets with high-strength and improved formability These standards ensure that the steel used in cable trays has adequate strength, corrosion resistance, and weldability for low voltage applications. BS EN Standards In Europe, BS EN 61537 specifies requirements for cable tray systems, including ladder, perforated, and solid-bottom trays. It covers design, testing, and installation practices to ensure safety and reliability .

Material and Fabrication Considerations

• Steel: Hot-dip galvanized or pre-galvanized steel is preferred for corrosion resistance. Stainless steel (e.g., AISI 316L) may be used in highly corrosive environments .
• Aluminum: Lightweight and corrosion-resistant, suitable for indoor low voltage rooms where mechanical load is moderate .
• Welding: Welded trays must maintain structural integrity and comply with the mechanical properties specified in ASTM or equivalent standards. Proper welding techniques should prevent overheating or weakening of the tray material .

Installation and Safety Guidelines

• Cable trays are supports for cables, not walkways or ladders. They must be installed by competent personnel familiar with electrical installation practices .
• Trays should be bonded to the building grounding system, typically connecting to a Telecommunications Grounding Busbar (TGB) or main grounding busbar (TMGB) in the room .
• Ventilated or solid-bottom trays may be selected based on cable type, heat dissipation requirements, and electromagnetic interference considerations .

Summary

For low voltage electrical rooms, welded metallic cable trays should:

1. Comply with NEMA VE-1 or equivalent IEC standards.
2. Use materials meeting ASTM A123, A653, A1011/A1008 or equivalent for steel.
3. Follow BS EN 61537 for design and installation practices.
4. Ensure proper grounding, corrosion protection, and safe installation by qualified personnel . These standards collectively ensure that cable trays are mechanically robust, electrically safe, and suitable for long-term use in low voltage environments.