Grounding jumper wire for cable trays

Grounding jumper wires provide a reliable electrical path between cable tray sections, ensuring safety and compliance with NEC standards.Purpose of Grounding JumpersGrounding jumper wires, also called bonding jumpers, are used to electrically connect separate sections of a cable tray system. They ensure that all metallic parts of the tray are at the same electrical potential, providing a safe path for fault currents to flow to ground. This reduces the risk of electric shock, equipment damage, and fire hazards .Materials and TypesCommon materials for grounding jumpers include tin-plated copper, copper, aluminum, and stainless steel. Tin-plated copper is widely used due to its excellent conductivity and corrosion resistance . Jumper wires may come as braided straps or stranded cables with crimped lugs and hardware for secure connections . Typical sizes range from #6 AWG to 2 AWG, depending on the system's fault current requirements and NEC specifications .Installation GuidelinesConnection Points: Bonding jumpers should be bolted directly to the cable tray channel, not to splice plate bolts or pins .Splices and Expansion: Install jumpers across adjustable splices and expansion splices to maintain electrical continuity .Mechanical Security: Use grounding clamps or hardware to anchor the jumper, preventing movement under fault current conditions .Wire Mesh Trays: For wire mesh cable trays, a separate grounding wire is recommended to ensure low impedance and reduce noise, especially when supporting cables with built-in EGCs .Aluminum Trays: Avoid bare copper in aluminum trays to prevent electrolytic corrosion; use insulated conductors with tin or zinc-plated connectors .Compliance with NECThe National Electrical Code (NEC) allows the cable tray itself to serve as an Equipment Grounding Conductor (EGC) in qualifying installations, but bonding jumpers are often used to ensure electrical continuity across tray sections . Key NEC considerations include:Permanent and electrically continuous grounding paths .Adequate cross-sectional area of tray side rails to carry fault currents .Proper sizing of EGCs when phase conductors are paralleled .Best PracticesMaintain low grounding resistance, ideally 4 ohms or less .Keep grounding wires clear of moisture, corrosive environments, and flammable materials .Ensure all connections are tight and corrosion-resistant to maintain long-term reliability . By following these guidelines, grounding jumper wires effectively protect personnel and equipment while ensuring compliance with electrical codes and standards.