Proper cable spacing within cable trays ensures safety, heat dissipation, EMI reduction, and ease of maintenance.

Rung Spacing

For ladder-type cable trays, rung spacing typically ranges from 6 to 18 inches, depending on cable type and size. Small-diameter control and instrumentation cables should use 6, 9, or 12-inch rung spacing to prevent drooping and maintain neat installation, while large power cables can use 9 inches or wider to accommodate bending radii and weight requirements (Eaton B-Line series) . Wider rungs and trays reduce overall strength, so load capacity must be considered.

Horizontal and Vertical Tray Spacing

• Horizontal spacing between power and signal trays should generally be at least 0.5 meters to minimize electromagnetic interference (EMI). If trays are shielded, spacing can be reduced to less than 0.3 meters .
• Vertical spacing between floor-mounted or stacked trays should be at least 150 millimeters (6 inches) to allow for airflow, heat dissipation, and future cable additions .
• Support span for horizontal runs is typically 1.5 to 3 meters, while vertical runs should have cables secured every 1.5 meters .

Cable Securing and Fill Limits

• Cables should be tied at the start, end, and turns, and every 3 to 5 meters along straight horizontal sections.
• Fill rate should not exceed 50% for control cables and 40% for power cables to ensure proper ventilation and prevent overheating .
• Unsupported spans from tray to equipment should not exceed 6 feet; otherwise, additional supports are required .

Additional Considerations

• Maintain at least 12 inches of vertical clearance above trays for installation and maintenance access .
• Use cable ties approved for tray applications to avoid fire hazards, especially in plenum spaces .
• Ensure minimum bending radii for cables are not violated when exiting trays . By following these spacing guidelines, cable tray installations will maintain structural integrity, reduce EMI, allow proper heat dissipation, and facilitate maintenance, ensuring long-term reliability and safety.