Section 250.60 allows the grounding electrode conductor for lightning protection systems to serve as the primary grounding electrode under which condition?

The provision in Section 250.60 specifies that the grounding electrode conductor for lightning protection systems can serve as the primary grounding electrode in buildings that are less than three stories. This is significant because shorter buildings often have different grounding needs compared to taller structures. Generally, the likelihood of lightning strikes increases with building height, and therefore, the design requirements for grounding systems can differ based on that factor. For buildings under three stories, using the lightning protection system's grounding electrode as the primary grounding method simplifies installation and may suffice for safety standards, given that they typically face a lower risk compared to taller structures. This specification likely ensures an appropriate balance of safety and practicality in grounding for structures of varied heights. The other options do not align with the specific criteria set forth in the code regarding building height and grounding requirements.