Requirements for installing cable trays in vertical shafts

Proper installation of cable trays in vertical shafts requires careful attention to support, spacing, cable fill, grounding, and compliance with safety standards. 1.

Tray Selection

Choose the appropriate type of cable tray based on the application and environment. Ladder trays are preferred for vertical shafts due to their excellent ventilation and ease of securing cables, while ventilated trough or solid-bottom trays may be used for sensitive instrumentation or areas requiring EMI protection. Material selection should consider corrosion resistance, mechanical strength, and environmental conditions, with options including galvanized steel, stainless steel, aluminum, or fiberglass-reinforced plastic.

2.

Support and Spacing

Vertical cable trays must be adequately supported to prevent sagging or excessive deflection. Cantilever wall brackets or trapeze hangers are commonly used, depending on shaft structure. Support spacing should follow manufacturer load charts and account for the total anticipated cable weight, including future additions.

Ensure that deflection limits are not exceeded to maintain structural integrity. 3.

Cable Fill and Management

Calculate the maximum cable fill according to NEC 392. 22 or relevant standards to prevent overheating and maintain ampacity. Maintain proper spacing between cables to reduce electromagnetic interference (EMI) and allow heat dissipation.

Use cable ties or clamps at intervals to secure cables without damaging insulation. 4.

Grounding and Bonding

Ensure all trays are properly bonded and grounded to prevent electrical hazards. Metal trays should be connected to the building grounding system, and continuity must be verified throughout the vertical run. 5.

Installation Safety

Perform a risk assessment before installation, including PPE requirements, LOTO procedures, and hot work permits if welding or cutting is involved. Only trained personnel should perform installations, and all work should comply with local electrical codes and standards such as IEC 60364, IEEE, and NEC. 6.

Pre-

Installation Preparation

Verify approved layout drawings and ensure they are labeled “Issued for Construction” (IFC). Inspect materials for quality and compliance with specifications before installation. Plan the vertical route to avoid structural conflicts and maintain accessibility for future maintenance.

7.

Maintenance Considerations

Design the installation to allow easy access for inspection, cable addition, or replacement. Avoid overloading the tray and ensure that covers, if used, can be removed safely without disturbing existing cables. By following these key points, cable trays in vertical shafts can be installed safely, efficiently, and in compliance with electrical standards, ensuring long-term reliability and ease of maintenance.