How to run cables through cable trays in a vertical shaft

Running cables through vertical shafts requires careful planning, proper support, and strict adherence to safety and code standards to prevent cable damage and ensure worker safety.

Planning and Preparation

Before installation, verify cable specifications, tray type, and shaft dimensions. Ladder-type trays are commonly used for vertical runs due to their ventilation and support capabilities, while ventilated troughs may be preferred for smaller control or instrumentation cables . Ensure the tray is sized correctly to avoid exceeding 40% cable fill, which prevents overheating and allows for future maintenance . Pre-plan the cable sequence and labeling to maintain organization and compliance with NEC/IEC standards .

Support and Securing

Vertical cable trays must be supported at regular intervals to handle the weight of the cables and prevent sagging. Use brackets or balusters designed for vertical applications, ensuring that the tray is anchored securely to the shaft walls . For long vertical runs, consider intermediate supports to reduce stress on the cables and tray.

Cable Pulling Techniques

Cable pulling in vertical shafts is high-risk due to gravitational forces. Always account for the weight of the cable and the tensile strength of the cable and pulling equipment . Use pulling grips or socks to distribute tension evenly and prevent cable damage. Implement fail-safe mechanisms, such as a secondary steel wire or braking system, to prevent free-fall accidents in case of a cable or grip failure . In some cases, pushing the cable with synchronized pushers along the shaft may be safer than pulling, especially for heavy or long cables.

Bend Radius and Cable Management

Maintain the minimum bend radius specified by the manufacturer to avoid insulation damage. Organize cables neatly within the tray, securing them at intervals to prevent movement and reduce mechanical stress . Segregate power, control, and communication cables to minimize interference and comply with code requirements.

Safety Considerations

Vertical installations should only be performed by trained professionals due to the high risk of injury and cable damage . Ensure proper personal protective equipment (PPE) is used, and follow all local electrical codes and safety regulations. Avoid exceeding the cable tray's load capacity and verify grounding and bonding requirements are met .

Summary

1. Pre-plan cable layout, tray type, and labeling.
2. Use ladder or ventilated trough trays with proper vertical supports.
3. Pull or push cables carefully, using grips, socks, and fail-safe mechanisms.
4. Maintain bend radius and secure cables at intervals.
5. Follow NEC/IEC standards and prioritize safety at all times. By following these steps, vertical cable tray installations can be executed safely, efficiently, and in compliance with industry standards.