Cables leading out of trough-type cable trays

Cables exiting trough-type cable trays should maintain proper bend radius, be supported, and use drop-outs or fittings to ensure safety and prevent damage.

Key Considerations for Cable Exits

Bend Radius: When cables leave a trough-type tray, it is critical to maintain the minimum bend radius specified by the cable manufacturer. This prevents insulation damage and ensures long-term reliability. Typically, a bend radius of 6 to 9 inches (150 to 230 mm) is recommended for instrumentation and control cables exiting the tray.

Drop-

Outs and Fittings: Trough-type trays often use drop-outs or specialized fittings to guide cables vertically or horizontally from the tray to equipment. These components protect cables from sharp edges and provide a controlled path for the exit. Support and Securing: Cables should be secured at intervals, usually not exceeding six feet, to prevent sagging or mechanical stress.

For tray cables like TC-ER or ITC-ER, continuous support using mechanical protection such as struts, angles, or channels is required when transitioning from the tray to equipment. Tray Design Impact: Trough-type trays, with solid or ventilated bottoms, provide continuous support for cables, reducing the risk of sagging and physical damage. Solid-bottom trays offer maximum protection, while ventilated trays allow heat dissipation and easier handling of multiple cables.

Material and Environment: The tray material (steel, aluminum, GRP, or concrete) affects installation and cable protection. For example, GRP trays are corrosion-resistant and non-conductive, making them suitable for harsh environments.

Practical Tips

Use radius control devices or rounded edges at exit points to prevent cable chafing. Ensure proper labeling and separation of power and control cables to reduce interference. Plan cable exits during the design phase to minimize sharp bends and maintain accessibility for maintenance.

Consider modular tray designs to allow easy expansion or rerouting of cables in the future. By following these guidelines, cables can safely exit trough-type cable trays while maintaining compliance with electrical standards and ensuring long-term operational reliability.