Spacing for direct installation of cable trays

Cable trays should be supported every 1.5 to 3 meters horizontally, with vertical and parallel tray clearances of at least 150 mm to ensure safety, maintenance access, and proper heat dissipation.

Horizontal Support Spacing

The distance between supports for cable trays depends on the tray type and load:

• Standard trays: supports every 6 to 10 feet (approximately 1.8 to 3 meters)
• Heavy-duty or long-span trays: can span up to 20 feet (6 meters) between supports
• Unsupported transitions to equipment or other raceways: maximum 6 feet (1.8 meters) before additional support is required
• Always consult the manufacturer's load capacity chart to determine proper support spacing based on cable weight and tray type .

Vertical and Parallel Tray Spacing

• Vertical spacing between floor-mounted or stacked trays: minimum 150 mm (6 inches) to allow airflow, heat dissipation, and future cable additions
• Parallel trays at the same height: minimum 0.6 meters (approximately 2 feet) to provide maintenance access and prevent cable contact
• Power and signal cable separation: generally at least 0.5 meters; if trays are shielded, spacing can be reduced to 0.3 meters .

Additional Considerations

• Rung spacing: for ladder-type trays, 150 to 230 mm (6 to 9 inches) is recommended to support instrumentation and control cables .
• Cable fastening: in vertical or angled runs, secure cables to transverse members; in horizontal runs, ties may be used to maintain spacing and improve heat dissipation .
• Clearance above trays: at least 12 inches (300 mm) for installation and maintenance access, as per the 2026 NEC update .
• Thermal expansion: for long outdoor runs, use expansion splice plates to accommodate temperature changes . Proper spacing ensures structural integrity, reduces electromagnetic interference, prevents overheating, and facilitates maintenance, making it essential to follow both NEC guidelines and manufacturer specifications when installing cable trays.