Laying of grounding busbar for high-voltage switchgear

The grounding busbar in high-voltage switchgear is typically installed behind the high-voltage loop switches, mounted on the wall at an accessible height, and extends along the length of the switchgear room for safe and reliable grounding connections.

Installation Location and Setup

In high-voltage switchgear rooms, the grounding busbar is usually a continuous copper bar, often 2 inches by 1/4 inch, mounted on standoff insulators to prevent unintended contact with the wall or other conductive surfaces. It is generally positioned behind the high-voltage loop switches and extends along at least two walls inside the room to ensure accessibility for all grounding connections. The busbar is typically installed at a height of around 30 inches above the floor, which allows easy access for maintenance personnel while maintaining safety.

Purpose and Connections

The grounding busbar serves as the central point for connecting all grounding conductors from the switchgear, circuit breakers, transformers, and other high-voltage equipment. This ensures that any fault current or induced voltage is safely directed to the earth, protecting both personnel and equipment. Each feeder and branch circuit should have a dedicated connection to the busbar, and conduit or equipment enclosures should not be relied upon as the grounding path.

Bonding bushings are recommended for conduit fittings, especially for feeders rated over 200 amps, to maintain a reliable grounding system.

Safety Considerations

Proper placement of the grounding busbar is critical for maintenance safety. It should be clearly accessible but isolated from live components to prevent accidental contact. In high-voltage switchgear, earthing switches are often interlocked with circuit breakers and disconnectors to ensure that grounding operations are performed safely and only when the equipment is de-energized.

This setup prevents accidental energization and ensures compliance with safety standards.

Summary

Material: Hard-drawn copper bar (2” x 1/4”)Mounting: On standoff insulators, ~30 inches above floorLocation: Behind high-voltage loop switches, along at least two wallsFunction: Central grounding point for all high-voltage equipmentSafety: Accessible for maintenance, isolated from live components, integrated with earthing switch interlocks This configuration ensures a reliable, safe, and standardized grounding system for high-voltage switchgear installations.