You are correct. The 2023 NEC, Article 250.24 regarding Grounding Service-Supplied Alternating-Current Systems, does not have a section (C)(1).It's possible you're: Using an older version of the NEC

The structure and section numbering can change between editions.

Misreading the reference

Double-check the exact citation in your document. Perhaps it's a slightly different article number.

Referring to a state or local amendment

Some jurisdictions amend the NEC. Check your local electrical codes.To give you a more precise answer, please let me know:

What year of the NEC are you using?* What is the context of the statement? What specific situation is the code section referring to? Knowing the context will help determine the intended regulation. Flag for review