Trough-type cable tray ground wire

A trough-type cable tray should be grounded using a continuous equipment grounding conductor or by bonding the tray sections together, ensuring a low-impedance path to earth for safety and NEC compliance.

Grounding Principles

All metallic cable trays, including trough-type trays, must be grounded to provide a safe path for fault currents and prevent electric shock or equipment damage ( ). Grounding ensures that any stray electrical currents are safely diverted into the earth, reducing the risk of fire or electrical hazards ( ).

Methods of Grounding

Using a Separate Grounding ConductorA continuous bare or insulated copper conductor can be run along the length of the trough tray. The conductor should be mechanically secured to the tray using grounding clamps at each section or joint to maintain electrical continuity ( ). Insulated conductors are preferred in aluminum trays to prevent electrolytic corrosion, with insulation removed at bonding points ( ).

Using the Tray as the Equipment Grounding Conductor (EGC)In qualifying facilities, the metallic tray itself can serve as the EGC if it meets NEC conductivity and cross-sectional area requirements ( ). Steel trays should not be used as EGCs for circuits with ground-fault protection above 600 A, and aluminum trays above 2000 A ( ). Tray sections must be electrically continuous, bonded at joints, and connected to a permanent ground ( ).

Bonding at Joints and Equipment ConnectionsEach tray section should be bonded to adjacent sections using tin- or zinc-plated connectors, bolts, or welds to ensure low impedance ( ). Equipment mounted on or connected to the tray should also be bonded to maintain a continuous grounding path ( ).

Material Considerations

Copper Wire: Excellent conductivity, corrosion-resistant, ideal for most installations.

Hot-

Dip Galvanized Steel: Durable and corrosion-resistant, suitable for industrial environments. Stainless Steel: Recommended for harsh or corrosive environments ( ).

Safety and Compliance

Grounding resistance should ideally be 4 ohms or less to ensure effective fault current dissipation ( ). Keep grounding conductors clear of flammable materials and moisture to prevent degradation.

Follow NE

C Article 392 and local electrical codes for installation, bonding, and grounding requirements ( ).

Summary

For a trough-type cable tray, the safest and most reliable approach is to either run a continuous grounding conductor along the tray or use the tray itself as the EGC if it meets NEC requirements. Proper bonding at joints, correct material selection, and adherence to grounding resistance standards are essential to ensure electrical safety and system reliability.