Spacing of cable tray end supports

At the ends of a cable tray, cables should be supported and secured within 6 feet of the transition to equipment or another raceway, with at least 12 inches of vertical clearance above the tray for maintenance access.

Key Guidelines for End Spacing

Unsupported Span: When cables transition from a tray to equipment or another raceway, the unsupported span should not exceed 6 feet. If the distance is longer, additional supports are required to prevent mechanical stress on the conductors and ensure safe operation. Vertical Clearance: The 2026 NEC specifies a minimum of 12 inches of clear vertical space above the cable tray.

This clearance allows for installation, inspection, and maintenance access, and helps with heat dissipation. Cable Securing: Cables at the tray ends should be fastened to the tray's transverse members or supported with listed cable ties to provide strain relief and prevent damage to terminations. Avoid overtightening ties to prevent jacket damage.

Support Spacing: Standard horizontal tray supports are typically spaced 6 to 10 feet apart, while heavy-duty or long-span trays can extend up to 20 feet between supports. At tray ends, ensure that supports are positioned close enough to maintain cable stability and prevent sagging. Transition Considerations: At corners, bends, or where trays meet equipment, it is recommended to install one hanger on each side symmetrically to distribute weight and maintain system integrity.

Additional Notes: For outdoor installations, UV-resistant ties should be used, and for vertical or angled runs, cables should be secured to prevent shifting. Proper spacing at tray ends also ensures compliance with NEC fill limits and reduces the risk of electromagnetic interference. By following these spacing and support guidelines, cable trays will maintain structural integrity, allow safe maintenance, and prevent undue stress on cables at transition points.