What is the NEC definition of an equipment grounding conductor?

The definition of an equipment grounding conductor specifically refers to a conductor that is utilized to connect non-current-carrying parts of equipment to the grounding electrode system. This is crucial for ensuring safety in electrical systems, as it helps to prevent electrical shock and equipment damage by providing a path for fault current to safely dissipate into the ground.

By connecting equipment frames and enclosures to the grounding electrode system, this conductor helps maintain the integrity of the system, especially during fault conditions where there may be a failure in insulation or a fault in the equipment. This path significantly reduces the risk of hazardous situations by effectively directing any fault currents away from the equipment and personnel.

The other options do not align with the NEC's definition of an equipment grounding conductor. For instance, the description of a wire that connects power sources to the electrical grid relates to system conductors rather than grounding conductors, and a cable that conducts electrical energy to devices pertains to power conductors. Additionally, the concept of isolating faults does not describe the grounding function, rather it pertains to circuit protection devices like circuit breakers or fuses. Thus, the correct choice emphasizes the grounding aspect that is crucial for safety in electrical installations.