Ground support for photovoltaic cable trays

Photovoltaic cable trays should be grounded by bonding all metallic parts to the equipment grounding system, using proper clamps and conductors to provide a low-impedance path for fault currents.

Key Principles

Grounding PV cable trays ensures safety, protects equipment, and stabilizes system voltage. All metallic cable trays must be bonded to the facility's grounding system, providing a low-resistance path for fault currents and lightning surges . This prevents shock hazards and protects sensitive PV equipment from overvoltage or transient events .

Equipment Grounding Conductor (EGC)

• The metallic cable tray itself can serve as the EGC if it meets the minimum cross-sectional area requirements specified in NEC Table 392.60(A), .
• If an EGC conductor is installed inside or alongside the tray, it should be bonded to each or alternate tray sections using grounding clamps to maintain electrical continuity and mechanical stability .
• Avoid using bare copper conductors in aluminum trays to prevent electrolytic corrosion; insulated conductors with exposed ends at bonding points are recommended .

Grounding Electrode Conductor (GEC)

• Connect the EGC from the PV array and cable trays to the grounding terminal of the inverter, which is ultimately tied to the AC grounding system and the premises grounding electrode .
• If separate grounding electrodes are used for DC and AC systems, they should be bonded at a common point to avoid multiple grounding loops, which can interfere with GFCI/AFCI devices and create transient voltage issues .
• Auxiliary grounding electrodes, if required, should be spaced at least 6 feet apart and at least 8 feet in length .

Bonding Practices

• Bond all metallic parts of the PV system, including module frames, racking, and cable trays, to the EGC to create a continuous low-impedance path .
• Use listed bonding devices to ensure compliance with NEC 250 and Article 690, maintaining electrical continuity and safety .
• Proper bonding also helps dissipate lightning energy and minimize electromagnetic interference (EMI) in sensitive PV electronics .

Installation Tips

1. Use tin- or zinc-plated connectors for bonding points to prevent corrosion.
2. Ensure mechanical stability of the EGC in the tray to withstand magnetic forces during fault conditions .
3. Verify that the tray material and size are suitable for the expected fault current rating. Steel and aluminum trays have different limitations for use as EGCs .
4. Maintain a single grounding path to the earth whenever possible to avoid loops and transient voltage issues . By following these practices, PV cable trays will be safely grounded, protecting personnel, equipment, and ensuring compliance with NEC and international standards .