Which type of grounding electrode is NOT compliant with the NEC when combined with a water pipe?

The grounding ring is not compliant with the NEC when combined with a water pipe because it cannot serve as a grounding electrode in conjunction with a water pipe. The NEC recommends specific types of grounding electrodes that can be safely combined with water pipes, mainly to ensure effective grounding and to maintain safety measures.

While other grounding electrodes, such as a copper-clad ground rod, a rigid metal conduit, or a metal underground water pipe, can be incorporated effectively into the grounding system, a grounding ring lacks the appropriate parameters set by the NEC for this application. Grounding rings are typically used as an additional form of grounding in certain scenarios, but they do not provide the same reliability or safety when tied in with water piping systems as the other options do.

Understanding this distinction is crucial for compliance with the NEC, which is designed to protect both structures and individuals from electrical hazards.