Spacing of horizontal supports for cable tray installation

For horizontal cable tray runs, supports are typically spaced between 1.5 meters and 3 meters, depending on tray type, load, and installation conditions.

Recommended Support Spacing

For straight horizontal sections of cable trays, the support span—the distance between supports—generally ranges from 1.5 meters to 3 meters. This spacing ensures structural stability, prevents sagging, and allows for easy maintenance and cable access (Apex Tray) . At corners, bends, or T-junctions, supports should be installed on each side of the turn, arranged symmetrically to prevent stress on the cables . For heavy-duty or long-span trays, supports can extend up to 6 meters, but this depends on the manufacturer's load capacity chart and the total weight of the cables (NEC 392) . Always consult the tray manufacturer for specific load ratings and maximum allowable spans.

Support Types and Installation

• Hanging rod supports should have a minimum diameter of 8 mm and be used where trays are suspended from ceilings or beams .
• Fixed supports should be placed at key points: the start and end of the tray, corners, T-junctions, and for spans exceeding 30 meters .
• Horizontal cable fastening: Cables should be secured at the start, end, turns, and every 3 to 5 meters along straight runs to maintain organization and prevent mechanical strain .

Additional Considerations

• Cable type and load: Heavier power cables require closer support spacing, while lighter signal cables may allow wider spans .
• EMI separation: Maintain at least 0.5 meters between power and signal trays to reduce electromagnetic interference; this can be reduced to 0.3 meters if trays are shielded .
• Vertical clearance: Ensure at least 150 mm between stacked trays for ventilation, heat dissipation, and future expansion .
• Fire safety: Use fire-resistant supports to prevent premature failure in case of fire, as required by BS 7671 and NEC standards .

Summary

• Straight horizontal runs: 1.5–3 meters between supports
• Heavy-duty/long-span trays: Up to 6 meters, per manufacturer guidance
• Corners/bends: Support on each side
• Hanging rods: Minimum 8 mm diameter
• Cable fastening: Every 3–5 meters along straight runs
• EMI separation: ≥0.5 m (≥0.3 m if shielded)
• Vertical clearance: ≥150 mm between trays Following these guidelines ensures structural integrity, cable safety, and compliance with electrical installation standards.