How to handle cables exiting the cable tray

Cables exiting a cable tray should be guided through proper dropouts, raceways, or flanged openings with bushings, maintaining bend radius, securing, and sealing to ensure safety and compliance.

Transition Methods

When cables leave a cable tray, they must be transitioned safely into equipment or other wiring systems. The 2020 NEC 392.46 specifies two main methods:

1. Through a raceway with a bushing – Cables enter the equipment via a conduit or tubing fitted with a bushing to protect the cable from abrasion and maintain proper support .
2. Through a flanged opening on the equipment – The opening should be sealed or covered to prevent debris from entering, with duct seal as an acceptable option . Both methods ensure cables are protected and reduce the risk of physical damage.

Cable Dropouts and Bend Radius

To maintain cable integrity, use dropout accessories designed for wire mesh or ladder trays:

• BDO (Basic Drop Out) – 4” wide, snap-in tabs, allows side or end drops without modifying the tray .
• SDO (Slotted Drop Out) – 6” or 12” wide, slotted for cable tie attachment, maintains bend radius .
• UDO (Universal Drop Out) – 8” to 24” wide, ideal for heavy copper or fiber optic bundles .
• CDO (Center Drop Out) – For high-capacity data centers, snaps in place, supports large bundles, and can be repositioned . These accessories prevent sharp bends and stress on cables, which could damage insulation or reduce performance.

Securing and Organizing Cables

• Cable ties or clamps should be used near connection points to relieve stress on terminations .
• Dividers in trays help separate power and data cables to prevent interference .
• Labeling at both ends and along the cable path ensures easy identification and maintenance .
• Documentation of cable routes and connections is essential for future troubleshooting .

Safety and Compliance

• Ensure the entire cable tray system is properly grounded to prevent electrical hazards .
• Check that the raceways, bushings, and flanged openings are sealed to prevent debris ingress .
• Follow local building codes and electrical standards for installation and maintenance .
• Regular inspections help maintain integrity and prevent damage over time . By following these practices, cables exiting a tray remain organized, protected, and compliant with safety standards, reducing the risk of electrical faults and improving system reliability.