Do galvanized cable trays require wiring

Yes, galvanized cable trays must be grounded, and wiring may be required depending on the installation and type of cables used.

Grounding Requirements

All metallic cable trays, including galvanized steel trays, must be grounded according to NEC Article 250. 96, regardless of whether the tray itself is used as an equipment grounding conductor (EGC) or not. Grounding ensures electrical safety by providing a low-impedance path for fault currents, reducing the risk of electric shock or fire.

Wiring Options for Grounding

There are three main approaches to providing an EGC in a cable tray system: EGC Conductor in or on the Cable Tray: A separate grounding wire runs along the tray and is bonded to each or alternate tray sections using grounding clamps. This also mechanically secures the conductor to prevent displacement under fault currents.

Individual EG

C in Each Cable: Each multi-conductor cable includes its own equipment grounding conductor. Tray as EGC: In qualifying installations, the metallic tray itself can serve as the EGC if it meets the minimum metal cross-sectional area requirements specified in NEC Table 392. 60(A).

For galvanized trays, bonding connections should use tin- or zinc-plated connectors, and bare copper conductors should generally be avoided in aluminum trays to prevent electrolytic corrosion.

Practical Considerations

Galvanized trays provide corrosion resistance and long-term durability, making them suitable for industrial and outdoor environments. Even with galvanized trays, if the cables already include EGCs, a separate grounding wire may not be strictly required, but bonding the tray to a system ground is recommended to reduce noise and stray currents. Proper installation ensures both mechanical support and electrical safety, especially in environments with moisture or chemical exposure.

Summary

While galvanized cable trays themselves are metallic and conductive, additional wiring in the form of an EGC is often required to comply with safety standards and NEC regulations. The choice between using the tray as the EGC or installing a separate grounding conductor depends on the type of cables, environmental conditions, and local electrical codes.