Are cable trays grounded

Yes, all metallic cable trays must be grounded to ensure electrical safety and compliance with NEC standards.Grounding RequirementsMetallic cable trays are required to be grounded under NEC Article 250.96 and Article 392 regardless of whether the tray itself is used as an equipment grounding conductor (EGC) or not . Grounding ensures that any electrical faults or leakage currents are safely directed to the earth, reducing the risk of electric shock, equipment damage, or fire .Methods of GroundingSeparate EGC Conductor: A dedicated grounding conductor (minimum #4 AWG) can be installed inside or attached to the tray .Tray as EGC: In some installations, the tray itself can serve as the EGC if it meets cross-sectional area 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: Sections of the tray are connected using bonding jumpers (thick green or copper wires) to maintain electrical continuity across joints .Insulated Conductors for Aluminum Trays: To prevent electrolytic corrosion, insulated conductors are recommended in aluminum trays, with insulation removed at bonding points .Safety and InspectionGrounding is critical for safety. Ungrounded trays can become energized during faults, posing a shock hazard . Inspections typically involve checking bonding jumpers with a multimeter; a low resistance reading (less than 0.01 ohms) indicates proper grounding . Special attention should be given to tray joints, splice plates, and connections, as vibrations or loose bolts can compromise continuity.Non-Metallic TraysNon-metallic cable trays cannot be used as grounding conductors. In critical installations, independent grounding lines using braided copper or galvanized conductors may be implemented .Benefits of Proper GroundingPrevents electrical leaks and reduces shock riskMinimizes interference and static electricityEnsures compliance with regulationsFacilitates safe maintenance and fault detection In conclusion, grounding metallic cable trays is mandatory and essential for electrical safety, and proper installation, bonding, and inspection practices are necessary to maintain a safe and reliable system.