Can cable trays be used as ground wires

Not all cable trays have a dedicated ground wire; metallic trays must be grounded, but grounding can be achieved via the tray itself or a separate equipment grounding conductor (EGC).Grounding RequirementsAll metallic cable trays must be grounded according to NEC Article 250.96, regardless of whether the tray is used as an equipment grounding conductor (EGC) or not . Grounding ensures that any stray electrical currents are safely conducted to earth, reducing the risk of electric shock, equipment damage, or fire .Methods of GroundingTray as Grounding Conductor: In some installations, the metallic tray itself can serve as the EGC if it meets NEC cross-sectional area and conductivity requirements . This method requires that the tray be electrically continuous and properly bonded at all splice points.Separate Grounding Conductor: A dedicated EGC can be installed inside or attached to the tray. This conductor is typically bonded to each tray section using clamps or connectors to maintain electrical continuity .Individual Cable EGCs: Multi-conductor cables may include their own EGCs, which can be connected to the tray or a common grounding conductor .Non-Metallic TraysNon-metallic trays, such as fiberglass-reinforced plastic (FRP), do not conduct electricity and therefore require a separate grounding conductor for safety . The tray itself cannot serve as a grounding path.Best PracticesEnsure all metallic tray sections are mechanically tight and electrically continuous .Use insulated conductors in aluminum trays to prevent electrolytic corrosion .Verify grounding conductor sizing according to NEC tables to handle potential fault currents .Maintain low grounding resistance (ideally 4 ohms or less) for effective fault current diversion . In summary, while metallic cable trays must be grounded, not all trays inherently include a ground wire. Grounding can be achieved through the tray itself, a separate conductor, or individual cable EGCs, depending on the installation and NEC compliance requirements. Non-metallic trays always require a separate grounding conductor.