Do all cable trays need to be grounded

All metallic cable trays must be grounded to ensure electrical safety, prevent shock hazards, and comply with NEC standards.Regulatory RequirementsAccording to the National Electrical Code (NEC), all metallic cable trays must be grounded regardless of whether they are used as an equipment grounding conductor (EGC) (NEC Article 250.96 and 392) . Grounding ensures that any fault current is safely directed to the earth, reducing the risk of electric shock, equipment damage, or fire . Cable trays can serve as the EGC in qualifying installations if they meet cross-sectional area and material requirements, but a separate EGC may also be installed for added safety .Methods of GroundingMechanical Bonding: Cable tray sections should be mechanically tight and electrically continuous. Bolts, splice plates, clamps, and bonding jumpers are used to connect sections and maintain continuity .Bonding Jumpers: Where mechanical connections alone are insufficient, bonding jumpers ensure a reliable grounding path between tray sections and to the building's grounding system .Separate EGC Conductor: A separate grounding conductor (minimum #4 AWG) can be installed inside or attached to the tray, bonded to each section .Material Considerations: Bare copper should not be used in aluminum trays due to corrosion risks; insulated conductors with proper bonding connections are recommended .Safety and Operational BenefitsGrounding cable trays provides multiple safety and operational benefits:Prevents electrical leaks by channeling fault currents safely to ground .Reduces shock hazards for personnel working near the trays .Minimizes electrical noise and interference, protecting sensitive electronic equipment .Ensures compliance with NEC and other regulatory standards, avoiding inspection failures .Special ConsiderationsNon-metallic trays cannot serve as grounding conductors and require separate EGCs .Steel trays are limited to circuits with ground-fault protection up to 600 amperes, while aluminum trays can handle higher ratings if properly bonded .In installations with only signal or low-energy circuits, grounding may focus on lightning protection and EMI mitigation rather than power fault currents . Proper grounding of cable trays is essential for a safe, reliable, and code-compliant electrical installation, and it should be planned carefully during system design and installation.