Under 2023 NEC 250.52(B), which item is prohibited from serving as a grounding electrode? The other options are assumed to meet their applicable electrode requirements.
- AA qualifying metal underground water-pipe electrode
- A metal underground gas piping system
- CA qualifying concrete-encased electrode
- DA qualifying copper ground ring
Where to look it up
https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P05_FD_PIResponses.pdf
Why B is correct
Metal underground gas piping is prohibited as an electrode. The prohibited list also includes aluminum and the pool structures/rebar identified by the rule, so it is not a two-item list. Bonding piping where required is a different function. Source: unchanged 2023 baseline in NFPA Public Input 2361, PDF page 201 (printed 140); its proposed additional prohibition is not used. https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P05_FD_PIResponses.pdf