Cables in metallic cable trays should be grounded using the tray as an equipment grounding conductor (EGC) or by bonding individual EGCs to the tray with proper clamps and connectors.

Using the Cable Tray as an Equipment Grounding Conductor

Metallic cable trays can serve as the EGC if they meet NEC requirements, ensuring a continuous, low-impedance path for fault currents . All metallic trays must be grounded regardless of whether they are used as the EGC . Steel trays should not be used for circuits with ground-fault protection above 600 A, and aluminum trays should not be used above 2000 A . The tray must be electrically continuous, and bonding between sections is required to maintain continuity .

Bonding Individual Grounding Conductors

If individual equipment grounding conductors (EGCs) are installed in or on the tray, they should be bonded to each or alternate tray sections using grounding clamps . This ensures mechanical stability and electrical continuity under fault conditions. For aluminum trays, use insulated conductors to prevent electrolytic corrosion, removing insulation only at bonding points with tin- or zinc-plated connectors .

Grounding Materials and Methods

• Flexible jumpers with lugs can connect tray sections to the grounding system .
• Braided copper or galvanized conductors are recommended for independent grounding lines in critical installations like industrial facilities or solar plants .
• Brass tray grounding terminals should be installed at specific intervals using grounding clamps to maintain a reliable connection .

Best Practices

• Lay grounding conductors parallel to the cable in the tray .
• Connect cable screens to the grounding system at both ends to reduce electrical noise and static buildup .
• Ensure compliance with NEC Article 392 for metallic trays, tray fill limits, and separation of power and data cables .
• Avoid placing bare copper conductors in aluminum trays in moist environments to prevent corrosion . Proper grounding in cable trays prevents electrical leaks, reduces shock hazards, minimizes interference, and ensures safe maintenance . Following these methods ensures both regulatory compliance and long-term system reliability.