Cable tray cross-connection grounding

Cable trays and conduits can be cross-grounded using a properly sized equipment grounding conductor (EGC), with metallic trays sometimes serving as the EGC if they meet NEC and manufacturer requirements. Using Cable Trays as Equipment Grounding ConductorsMetallic cable trays can serve as the equipment grounding conductor (EGC) in qualifying installations, provided they meet NEC Section 318-3(c) and have sufficient cross-sectional metal area to safely carry fault currents. When a tray is used as an EGC, it must be permanently and electrically continuous, capable of conducting fault current, and bonded to all tray sections using grounding clamps or mechanical connectors.

For aluminum trays, insulated conductors are recommended to prevent electrolytic corrosion, with insulation removed at bonding points.

Grounding Multiple Raceways and Conduits

When multiple conduits run in parallel to a load, each conduit generally requires its own EGC sized according to NEC 250. 122. If a cable tray is present, a single EGC in the tray can be tapped at the ends to serve the conduits, provided the tray itself is properly bonded and sized to carry the fault current.

The tray may also serve as the EGC if it is aluminum with a cross-sectional area of at least 1 square inch or steel meeting manufacturer specifications.

Bonding Practices

Mechanical bonding: Use grounding clamps, threaded rods, or manufacturer-supplied bonding jumpers to ensure continuity across tray sections.

Parallel EG

Cs: For multiple circuits in a tray, a single conductor can serve as the common EGC, but each raceway must still meet NEC grounding requirements.

U

L Classification: Modifications such as cutting trays may affect UL classification; ensure bonding maintains electrical continuity and compliance.

Practical Recommendations

Evaluate tray cross-section: Confirm the tray's metal area is sufficient for the highest-rated protective device in the circuit. Use insulated EGCs in aluminum trays: Prevent corrosion and maintain reliable bonding. Bond at regular intervals: Typically every 50–65 feet or per manufacturer instructions.

Separate EG

Cs for conduits: Each conduit should have an EGC unless the tray is explicitly sized and bonded to serve multiple conduits. By following these practices, cable trays and conduits can be safely cross-grounded, ensuring compliance with NEC standards and effective fault current management.