What condition makes it unnecessary to ground a metal component installed in PVC conduit?

Grounding of metal components is primarily concerned with safety, particularly to prevent electric shock and to ensure proper operation of electrical systems. When a metal component is encased in concrete, grounding is not required because the concrete serves as an effective barrier and insulator. The conductivity pathways that could lead to a fault are greatly minimized in this case.

Concrete is considered a permanently installed, durable material, and when a metal component is fully embedded in it, it is generally protected from physical damage, and any potential for it to become energized is mitigated. This reduces the necessity for additional grounding measures since the metal is not exposed and cannot readily become a shock hazard.

In contrast, the other conditions listed do not provide the same level of inherent safety or isolation from electric fault conditions, which explains why grounding would still be necessary in those scenarios. Encasing in a wall or being below the frost line does not eliminate the risks associated with loose connections or other failure modes, while bearing walls do not imply any insulation from electric conduction.