Do ground-mounted cable trays need to be fixed

Yes, ground-mounted cable trays must be properly fixed and grounded to ensure mechanical stability and electrical safety.

Mechanical Fixing

Ground-mounted cable trays need to be securely anchored to the floor or supporting structures to prevent movement, tipping, or vibration that could damage cables or compromise safety. Bolted connections, brackets, or support posts are commonly used to fix the trays in place. Proper fixing ensures that the trays can safely support the weight of the cables and withstand environmental forces such as wind or accidental impact, especially in industrial or outdoor installations .

Grounding and Bonding

All metallic cable trays must be grounded, regardless of whether they are used as an equipment grounding conductor (EGC) or not, as required by NEC Article 250.96 . Grounding provides a low-impedance path for fault currents, protecting personnel and equipment from electrical hazards, including electric shock, fire, and equipment damage . Key grounding practices include:

• Bonding tray sections together using grounding clamps or jumpers to maintain electrical continuity .
• Using a separate EGC conductor inside or attached to the tray if the tray is not rated as an EGC .
• Avoiding bare copper conductors in aluminum trays in moist environments to prevent galvanic corrosion; insulated or aluminum conductors with proper connectors are recommended .
• Ensuring that steel trays are limited to circuits with ground-fault protection up to 600 amperes, while aluminum trays can handle higher ratings .

Inspection and Compliance

Grounding and fixing should be inspected before energizing the cables. Each tray section must be connected and bonded properly, either by bolted connections or bonding jumpers, to ensure compliance with NEC standards . Regular inspections help maintain safety and system reliability over time.

Summary

Ground-mounted cable trays must be fixed mechanically to prevent movement and properly grounded to ensure electrical safety. Following NEC guidelines and best practices for bonding, conductor selection, and inspection is essential for safe and reliable cable tray installations .