How to ground indoor cable trays

Yes, all metallic indoor cable trays must be grounded to ensure electrical safety and compliance with NEC standards.NEC Compliance and SafetyAccording to the National Electrical Code (NEC) Article 392, metallic cable trays must be electrically continuous, properly bonded at all splice points, and connected to the building's grounding system to prevent shock hazards and equipment malfunctions . Grounding ensures that any stray electrical currents or faults are safely directed to the earth, reducing the risk of electric shock, fire, or damage to equipment .Methods of GroundingUsing a Separate Equipment Grounding Conductor (EGC): A dedicated grounding wire, typically #4 AWG or larger, can be installed inside or attached to the tray. This conductor is bonded to each tray section to maintain continuity .Cable Tray as EGC: In some installations, the tray itself can serve as the grounding conductor if it meets cross-sectional area and conductivity requirements. Steel trays are limited to circuits with ground-fault protection up to 600 amperes, while aluminum trays can handle up to 2,000 amperes .Bonding Jumpers: Where mechanical connections alone do not provide reliable electrical continuity, flexible bonding jumpers with appropriate lugs are used to connect tray sections and ensure a continuous grounding path .Material ConsiderationsAluminum Trays: Avoid bare copper conductors due to potential electrolytic corrosion; insulated conductors with exposed bonding points are recommended .Steel or Copper Conductors: Hot-dip galvanized steel, copper, or stainless steel are preferred for durability, conductivity, and corrosion resistance .Additional BenefitsGrounding cable trays also reduces electrical noise and interference, prevents static electricity buildup, and facilitates safe maintenance and troubleshooting . Properly grounded trays contribute to a stable and compliant electrical infrastructure, especially in environments with sensitive electronic equipment.Best PracticesEnsure all tray sections are mechanically tight and electrically continuous.Verify grounding conductor sizing according to NEC tables.Maintain proper bonding at all splice points and connections to equipment enclosures.Avoid overfilling trays to maintain airflow and prevent overheating, which can compromise grounding effectiveness . In summary, grounding metallic indoor cable trays is mandatory for safety, regulatory compliance, and reliable operation, and it should be implemented using either a dedicated EGC, the tray itself (if qualified), or bonding jumpers with proper materials and connections.