A ground ring conductor must be buried at least how deep below the earth's surface?

The requirement for a ground ring conductor to be buried at least 30 inches below the earth's surface is based on safety standards and guidelines established by the National Electrical Code (NEC). The depth ensures that the conductor is adequately protected from physical damage, which could occur from surface activities or environmental factors.

Burying the conductor at this recommended depth also helps in reducing the risk of electrical interference and ensures a proper ground path, which is essential for the safety and functionality of electrical systems. Ground rings are typically installed around buildings to dissipate fault currents safely into the earth, and maintaining proper depth is crucial for their effectiveness.

The other options suggest depths that are either too shallow or unnecessarily deep, which may not align with the established electrical codes or best practices for grounding installations. By adhering to the 30-inch guideline, compliance with safety regulations and effective grounding techniques are achieved.