Standard Requirements for Custom-Made Cable Trays in Vertical Shafts

Vertical shaft cable trays must comply with IEC 61537, NEMA VE 1, UL 568, and NEC/CEC installation standards to ensure safety, structural integrity, and electrical performance. Key Standards and CodesIEC 61537 is the internationally recognized standard for metal cable tray systems, including vertical installations. It specifies construction requirements, load testing, deflection limits, and electrical continuity for trays made of steel, stainless steel, aluminum, or other metallic materials.

Compliance ensures trays can safely support cable weight over vertical spans and maintain grounding continuity with a resistance of less than 0. 1 ohms across joints.

NEMA V

E 1 provides manufacturing and installation requirements for metal cable trays, including ladder, channel, wire mesh, and solid-bottom types. It defines load/span classes, material specifications, and fittings suitable for vertical runs, ensuring structural stability and proper cable support. For nonmetallic trays, UL 568 covers performance and safety requirements, including fiberglass ladder and trough systems, which are often used in corrosive or high-moisture environments.

National Electrical Code (NEC, NFPA 70) and Canadian Electrical Code (CEC, C22. 1 Part 1) govern installation practices, including vertical tray spacing, support intervals, and ampacity considerations for conductors. Article 310 of the NEC provides guidance on conductor ampacities, which is critical when designing vertical cable shafts to prevent overheating.

Design and Installation Considerations

Rung Spacing and Cable Support: Vertical trays typically use rung spacing of 6–9 inches (150–230 mm) to maintain cable positions and prevent sagging. Material Selection: Steel, stainless steel, aluminum, and fiberglass are chosen based on environmental conditions, corrosion resistance, and mechanical strength. Stainless steel (AISI 316L) is preferred in corrosive environments, while aluminum offers lightweight and corrosion-resistant options.

Load and Deflection: Vertical trays must be designed to handle the cumulative weight of cables over the shaft height.

IE

C 61537 provides formulas for working load and safety margins, and trays are tested for deflection and yield strength at various spans. Electrical Continuity: When used as part of an earthing system, vertical trays must maintain low-resistance continuity to safely carry fault currents. Thermal Expansion: Vertical shafts must account for thermal contraction and expansion, especially in long runs or extreme temperature environments.

Fittings and Supports: Proper fittings, splice plates, and support brackets are required at intervals to maintain alignment and structural integrity.

Best Practices

Ensure all vertical tray installations are engineered for the specific cable load and environmental conditions. Verify compliance with local electrical codes and obtain necessary certifications (UL, CE, or third-party testing). Use solid or ventilated covers as needed to protect cables from dust, moisture, or mechanical damage.

Periodically inspect vertical shafts for corrosion, mechanical damage, or loose fittings to maintain long-term safety and performance. By adhering to these standards and guidelines, vertical shaft cable trays can provide safe, reliable, and code-compliant support for power, control, and communication cables in commercial, industrial, and utility installations.