How to secure the cable tray for under-line wiring

Cable trays for under-line wiring should be securely mounted using appropriate support brackets, hardware, and spacing according to NEC Article 392 and industry best practices to ensure safety and structural integrity.

Selecting the Right Tray and Support

Choose a cable tray type suitable for your application. Ladder trays are ideal for power cables and large conductors due to ventilation and convenient anchor points, while ventilated troughs provide continuous support for smaller control or instrumentation cables . For corrosive or high-moisture environments, fiberglass-reinforced plastic (FRP) trays offer non-conductive, corrosion-resistant support .

Mounting and Securing the Tray

1. Support Brackets and Hardware: Use manufacturer-recommended brackets, hardware kits, and splices to attach trays to walls, ceilings, or under-line structures . Bolted splices connect tray sections end-to-end and secure intersections.
2. Spacing: Support spans should follow NEC Article 392 and manufacturer guidelines, typically every 4–6 feet for ladder trays and closer for heavier loads . Ensure supports can handle the weight of cables and any imposed loads, including short-circuit forces .
3. Leveling and Alignment: Ensure trays are level and aligned to prevent cable sagging. Use adjustable brackets or expansion bars for elevation changes .
4. Bundling and Cable Management: Secure cables within the tray using cable ties or banding, keeping bundles balanced and avoiding overfilling . Integrated sidewalls in wire basket trays help contain cables and prevent displacement .

Bonding and Grounding

All metal trays must be properly bonded and grounded to prevent electrical hazards. Ensure continuity across splices and connections, following NEC requirements .

Additional Considerations

• Avoid using trays as walkways or for supporting personnel .
• Use corrosion-resistant finishes (powder coat or electro-zinc) for long-term durability .
• Verify that the tray system is compatible with the cables being installed, considering voltage, insulation type, and environmental exposure . By following these steps, under-line cable trays can be securely installed, code-compliant, and safe for long-term operation, while allowing easy maintenance and future cable additions.