Clause-by-clause translation of NEC Article 250: system and equipment grounding, electrodes (2.44 m rods), Table 250.66 sizes, bonding.
| Document | NEC 2023, Article 250 Grounding and Bonding |
| Edition | 2023 |
| Status | Current (latest NEC edition) |
| Issued by | NFPA |
| Applies to | Grounding and bonding: electrodes, conductors, bonding |
| № | Chapter / section |
|---|---|
| 250.1–250.10 | General, terms |
| 250.30–250.36 | Separately derived systems |
| 250.50–250.66 | Grounding electrodes |
| 250.100–250.122 | Conductors, connections, sizes |
Article 250 covers grounding of systems/equipment and bonding.
250.4 Effective fault current path, voltage limits on enclosures, neutral grounding.
250.6 Earth must not be the sole conductor.
250.24 Neutral grounded at the service; main bonding jumper only at the service (250.24(C)).
250.30 Separately derived systems (generators, transformers) — own electrode.
250.50 All available electrodes bonded together.
250.52 Allowed: metal water pipe (first 1.5 m), rod 2.44 m (8 ft) long, ≥ 15.9 mm (5/8 in) copper-clad steel, plate, Ufer (rebar), cable sheath.
250.53 Rods below frost line; > 25 Ω — second rod.
250.66 Sizing table for grounding electrode conductor by phase size.
250.110–114 Equipment enclosures grounded; receptacles via earthing contact.
250.119 EGC green/green-yellow; neutral white/gray.
250.122 EGC table by breaker rating: 15 A — 14 AWG, 20 A — 12 AWG, 60 A — 10 AWG.
250.148 Bonding of boxes and receptacles.
Article 250 is the US equivalent of PUE 1.7: mandatory electrode list (2.44 m rod) instead of "4 Ω", sizing by tables 250.66/250.122, N-G jumper only at the service (like the PUE 1.7.135 prohibition).
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