Installation spacing of vertical supports for cable trays

Vertical supports for cable trays should generally be spaced at intervals of 1.5 to 2 meters, with additional strain relief for long runs to prevent mechanical stress.

General Guidelines

For vertical cable tray runs, supports must be fixed to the building structure to prevent undue mechanical strain on the cables and terminations. The recommended spacing for vertical supports is preferably less than 2 meters, depending on the tray type, cable weight, and manufacturer specifications . Cables should be secured at the top of the vertical run and at intervals of approximately 1.5 meters along the tray to maintain organization and prevent sagging .

Long Vertical Runs

For extended vertical runs exceeding 32 meters, it is recommended to incorporate strain relief sections. This can be achieved by offsetting the cable horizontally by at least 2 cable diameters at one point along the run to relieve tension . For extremely long runs (over 100 meters), additional measures such as multiple tension-relieving sections may be necessary to prevent cable damage.

Horizontal vs Vertical Considerations

While horizontal tray supports typically range from 1.5 to 3 meters depending on load and tray type, vertical runs require closer spacing due to the effect of gravity on the cable weight . At bends or transitions from vertical to horizontal, supports should be installed on either side of the bend to maintain stability and protect the cables from stress .

Compliance and Safety

Support spacing must also comply with the National Electrical Code (NEC 392.30), which requires adherence to the manufacturer's load capacity charts and limits on unsupported spans . Proper vertical support spacing ensures mechanical stability, prevents conductor damage, and allows for safe installation and maintenance access.

Summary Recommendations

• Vertical support spacing: 1.5–2 meters for standard runs
• Cables secured: Top of run and every 1.5 meters
• Long runs (>32 m): Include strain relief offsets
• Extremely long runs (>100 m): Additional tension relief measures
• Bends and transitions: Support on both sides of the bend
• Compliance: Follow NEC and manufacturer guidelines Following these guidelines ensures structural integrity, safety, and compliance with electrical installation standards while minimizing mechanical stress on cables.