When applying NEC standards, which of the following is NOT considered a grounding conductor?

In the context of the National Electrical Code (NEC) standards, a grounding conductor is primarily used to direct fault currents safely to the ground, thereby protecting people and equipment from electric shock and damage. The materials specified for grounding conductors generally include those that can effectively conduct electricity, such as insulated or bare copper wires.

Green insulated wire is a recognized color for grounding conductors, indicating its purpose. Bare copper wire serves the same function without insulation. "Other approved grounding conductors" may refer to alternative materials or configurations that meet NEC requirements for grounding.

The distinction for the white insulated wire comes from its standard use in electrical wiring. According to NEC guidelines, white insulated wire is designated as a neutral conductor rather than a grounding conductor. This means that while it can be involved in circuit return path applications, its primary role is not safety grounding, but rather the balancing of electrical loads. Therefore, it does not qualify as a grounding conductor under NEC standards, making it the correct answer to identify what is NOT considered a grounding conductor.