Standards for Fabrication of Cable Tray Bends

Cable tray bends must be manufactured according to IEC 61537, NEMA VE 1, and UL 568 standards, ensuring proper dimensions, load capacity, and material compliance.

Key Standards

IEC 61537 specifies requirements and tests for all types of cable tray systems, including bends, elbows, and other fittings, for supporting and accommodating electrical and communication cables. It covers metallic and nonmetallic trays, defining mechanical strength, corrosion resistance, and dimensional tolerances for bends to ensure safe cable routing and system integrity . NEMA VE 1 provides detailed manufacturing requirements for metal cable trays and associated fittings, including ladder, ventilated, solid bottom, and channel trays. It defines load/span classes, bend radii, and material specifications for bends to maintain structural performance under expected cable loads . UL 568 applies to fiberglass (nonmetallic) cable trays, including bends, and specifies construction, performance, and safety tests to ensure the trays can withstand mechanical stress, environmental conditions, and fire hazards .

Material and Fabrication Considerations

• Steel and Stainless Steel: Typically AISI 316L or equivalent, with chromium content for corrosion resistance. Bends are fabricated to maintain mechanical strength and prevent stress points .
• Aluminum: Selected alloys provide corrosion resistance and formability; bends must preserve structural integrity and avoid cracking .
• Nonmetallic (Fiberglass/Resin): Pultrusion or molding processes are used to produce bends with high resistance-to-weight ratios and chemical resistance .

Bend Design Requirements

• Minimum Bend Radius: Must accommodate the cable type and prevent damage; generally, the radius is at least 6–10 times the cable diameter for power and control cables .
• Load and Span Ratings: Bends must meet the same load/span class as straight sections to ensure uniform support .
• Compatibility: Bends should be designed to integrate seamlessly with straight tray sections and other fittings, maintaining system continuity and safety .

Compliance and Testing

• Mechanical Testing: Bends are tested for deflection, impact resistance, and load-bearing capacity according to IEC 61537 or NEMA VE 1.
• Environmental Testing: Corrosion, UV, and chemical resistance tests are required for outdoor or harsh environments.
• Certification: CE marking (Europe), UL listing (USA), or equivalent national certifications ensure compliance with safety and performance standards .

Summary

Manufacturing cable tray bends requires adherence to international and national standards to ensure mechanical strength, proper bend radius, material durability, and safety compliance. Key references include IEC 61537 for general cable tray systems, NEMA VE 1 for metallic trays, and UL 568 for fiberglass trays, with additional guidance from NEC, CEC, and national regulations for installation and performance .