Setting up cable tray jumpers

Bonding jumpers are required at expansion joints and adjustable splices, but not at standard bolted splice plates if proper metallic continuity is maintained.

General Guidelines

For standard metallic cable tray systems, properly installed rigid splice plates provide electrical continuity between tray sections, meeting NEC requirements for grounding and bonding. In these cases, additional bonding jumpers are not necessary because the splice plates themselves maintain electrical continuity and safely conduct fault currents (NEC Section 392. 60 and 250.

96).

When Bonding Jumpers Are Required

Expansion Splices and Adjustable Fittings: Cable trays that include expansion joints or adjustable splices require bonding jumpers to maintain electrical continuity across the discontinuity. The jumper should be bolted directly to the tray channel, not to the splice plate bolts or pins. Long Runs and Outdoor Installations: For long cable tray runs, especially outdoors, bonding jumpers should be installed at intervals (typically every 15 m / 50 ft) and at both ends of the tray to ensure proper grounding and safety.

Conduit Drop-

Outs: Any conduit or cable drop-outs from the tray should be bonded to the tray using a compression lug or grounding bushing to maintain continuity.

Installation Recommendations

Use 2 AWG soft drawn tin-plated copper stranded cable for jumpers, with flame-retardant PVC insulation resistant to abrasion, oil, and chemicals. Bolt each lug to a 5/16 square hole at the end of the tray channel. Do not use splice plate bolt locations for jumper connections.

Ensure that all metallic equipment enclosures and supports that may become energized are bonded back to the system's equipment grounding conductor. For standard bolted splice plates, use two steel or stainless steel bolts per side rail to reduce temperature rise and maintain fault current capacity.

Compliance and Safety

All cable tray installations must comply with the latest NEC, NEMA VE 2, and manufacturer instructions. Proper bonding ensures that fault currents are safely conducted, protecting personnel and equipment. Testing and verification of electrical continuity are recommended, especially for expansion joints and long runs.

By following these guidelines, cable tray systems will maintain proper grounding, electrical continuity, and compliance with safety standards.