NEC 215.2(B) → 235.202

The one thing that will confuse you if you're holding a 2017 code and a 2023 code

The over-600-volt feeder rules do not live in Article 215 in the 2023 NEC. In 2017, "Feeders over 600 Volts" was 215.2(B) — a subsection inside Article 215, right next to the ≤600 V rules. By 2023, that entire over-1000-V feeder set has been moved into the new Article 235, Part III, and the headline section is now 235.202. If a 2017 drawing or spec cites "215.2(B)" for a medium-voltage feeder, the correct 2023 cross-reference is "235.202".

That move did not happen all at once. It took two editions. In 2020 the section was still 215.2(B), but its heading changed from "Feeders over 600 Volts" to "Feeders over 1000 Volts" (the 600→1000 V migration) and its ampacity citations changed from 310.15/310.60 to 310.14/315.60. In 2023, the already-1000-V section was relocated out of Article 215 into Article 235 Part III and renumbered to 235.202, with its three subsections becoming 235.202(A)/(B)/(C). This article documents all three states, verbatim, and pins every change to the edition it landed in.

The centerpiece: 215.2(B) in 2017 — "Feeders over 600 Volts"

(B) Feeders over 600 Volts. The ampacity of conductors shall be in accordance with 310.15 and 310.60 as applicable. Where installed, the size of the feeder-circuit grounded conductor shall not be smaller than that required by 250.122, except that 250.122(F) shall not apply where grounded conductors are run in parallel. Feeder conductors over 600 volts shall be sized in accordance with 215.2(B)(1), (B)(2), or (B)(3).

(1) Feeders Supplying Transformers. The ampacity of feeder conductors shall not be less than the sum of the nameplate ratings of the transformers supplied when only transformers are supplied.

(2) Feeders Supplying Transformers and Utilization Equipment. The ampacity of feeders supplying a combination of transformers and utilization equipment shall not be less than the sum of the nameplate ratings of the transformers and 125 percent of the designed potential load of the utilization equipment that will be operated simultaneously.

(3) Supervised Installations. For supervised installations, feeder conductor sizing shall be permitted to be determined by qualified persons under engineering supervision. Supervised installations are defined as those portions of a facility where all of the following conditions are met: (1) Conditions of design and installation are provided under engineering supervision. (2) Qualified persons with documented training and experience in over 600-volt systems provide maintenance, monitoring, and servicing of the system.

The 2020 transition: same section, 1000 V, new tables

In the 2020 edition the section was still 215.2(B) — but it had already absorbed the 600→1000 V migration and the ampacity-table renumber. Two changes, both visible verbatim:

(B) Feeders over 1000 Volts. The ampacity of conductors shall be in accordance with 310.14 and 315.60 as applicable. Where installed, the size of the feeder-circuit grounded conductor shall not be smaller than that required by 250.122, except that 250.122(F) shall not apply where grounded conductors are run in parallel. Feeder conductors over 1000 volts shall be sized in accordance with 215.2(B)(1), (B)(2), or (B)(3).

(3) Supervised Installations. For supervised installations, feeder conductor sizing shall be permitted to be determined by qualified persons under engineering supervision in accordance with 310.14(B) or 315.60(B). Supervised installations are defined as those portions of a facility where all of the following conditions are met: (1) Conditions of design and installation are provided under engineering supervision. (2) Qualified persons with documented training and experience in over 1000-volt systems provide maintenance, monitoring, and servicing of the system.

The 2023 destination: 235.202 — "Feeder conductors over 1000 volts"

In 2023 the section is no longer in Article 215. It is 235.202 in the new Article 235 Part III ("Feeders over 1000 Volts, Nominal"). Part III's scope statement, verbatim from the 2023 CSV:

235.201 Scope. Part III covers the installation requirements, overcurrent protection requirements, minimum size, and ampacity of conductors for feeders over 1000 volts ac or 1500 volts dc, nominal.

And the relocated sizing section itself. The lead sentence is word-identical to the 2020 215.2(B) lead (modulo the cleaned 315.60 citation):

The ampacity of conductors shall be in accordance with 310.14 and 315.60 as applicable. Where installed, the size of the feeder-circuit grounded conductor shall not be smaller than that required by 250.122, except that 250.122(F) shall not apply where grounded conductors are run in parallel. Feeder conductors over 1000 volts shall be sized in accordance with 235.202(A), (B), or (C).

(A) The ampacity of feeder conductors shall not be less than the sum of the nameplate ratings of the transformers supplied when only transformers are supplied.

(B) The ampacity of feeders supplying a combination of transformers and utilization equipment shall not be less than the sum of the nameplate ratings of the transformers and 125 percent of the designed potential load of the utilization equipment that will be operated simultaneously.

(C) For supervised installations, feeder conductor sizing shall be permitted to be determined by qualified persons under engineering supervision in accordance with 310.14(B) or 315.60(B). Supervised installations are defined as those portions of a facility where all of the following conditions are met: Conditions of design and installation are provided under engineering supervision. Qualified persons with documented training and experience in over 1000-volt systems provide maintenance, monitoring, and servicing of the system.

The relocation map (the centerpiece table)

Every over-600-V feeder provision from 2017, and where it lands in 2023. "Verbatim" means the body text is character-identical after the disclosed OCR corrections; "cleaned" means the citation was corrected (no rule change).

The through-line: the rule content of (A) and (B) is identical in all three editions — the only things that changed are the section number, the voltage threshold (600→1000 V in 2020), the ampacity-table citations (310.15/310.60 → 310.14/315.60 in 2020), and the physical home (Art. 215 → Art. 235 in 2023). The supervised route (C) is the only one with a real content addition, and that landed in 2020, not 2023.

The rest of Article 215: what renumbered in 2023

The over-1000-V relocation is the headline, but the 2023 restructuring also reshuffled the ≤1000 V feeder sections. The 215.2 subsections were relettered as the article was reorganized:

Other Article 215 deltas, 2017 → 2023, edition-pinned

Beyond the relocation and the 215.2 relettering, these are the other changes I verified against the on-disk text, each pinned to the edition it landed in:

• 215.1 (Scope) — 2023: gained the voltage cap. 2017/2020: "…ampacity of conductors for feeders." (no voltage limit; 2017 has an electrolytic-cell Exception). 2023: "…for feeders not over 1000 volts ac or 1500 volts dc, nominal. Informational Note: See Part III of Article 235 for feeders over 1000 volts ac or 1500 volts dc." This is the scope statement that formalizes the relocation.
• 215.3 (Overcurrent) — 2020: Exception No. 2 (the 600–1000 V / Part IX routing exception) was deleted in 2020, leaving a single unnumbered Exception. 2023 keeps the single Exception and drops the words "the provisions of." The 2023 text, verbatim: "Feeders shall be protected against overcurrent in accordance with Part I of Article 240. Where a feeder supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcurrent device shall not be less than the noncontinuous load plus 125 percent of the continuous load." (The deleted 2017 text routed 600–1000 V feeders to "Parts I through VII of Article 240" and over-1000 V feeders to "Part IX" — verified against the 2017 scan and the 2017 Article 240 part headings on disk. One source-quality note: the AJB 2020 change newsletter mis-quotes the deleted text as "Parts I through VIII … Part X"; the on-disk 2017 print text is "Parts I through VII … Part IX.")
• 215.9 (GFCI for personnel) — 2020 & 2023: in 2017 limited to "15- and 20-ampere receptacle branch circuits"; in 2020 that limitation was dropped (applies to feeders generally); in 2023 the word "listed" was added. The 2023 text, verbatim: "Feeders shall be permitted to be protected by a listed ground-fault circuit interrupter installed in a readily accessible location in lieu of the provisions for such interrupters as specified in 210.8 and 590.6(A)."
• 215.10 (Ground-Fault Protection of Equipment) — 2020 & 2023: (a) a new Exception No. 3 added in 2020 (temporary feeders without GFPE permitted for repair/maintenance/emergencies, not to exceed 90 days); (b) the phase-to-phase ceiling raised from "not exceeding 600 volts" (2017 + 2020) to "not exceeding 1000 volts" (2023) — this is the delta that makes 1000/577 V wye feeder disconnects require GFPE in 2023; (c) 2023 shortened the "The provisions of this section" lead to "This section" and the Info Note to "See 517.17." The 2023 text, verbatim: "Each feeder disconnect rated 1000 amperes or more and installed on solidly grounded wye electrical systems of more than 150 volts to ground, but not exceeding 1000 volts phase-to-phase, shall be provided with ground-fault protection of equipment in accordance with 230.95." — and the 2020-added Exception No. 3: "If temporary feeder conductors are used to connect a generator to a facility for repair, maintenance, or emergencies, ground-fault protection of equipment shall not be required. Temporary feeders without ground-fault protection shall be permitted for the time period necessary but shall not exceed 90 days."
• 215.6 (Feeder EGC) — 2020: dropped "in accordance with the provisions of 250.134" and changed "the requirements of 250.32(B)" to "the requirements of 250.32."
• 215.15 (Feeders) — NEW in 2023: barrier rule — "Barriers shall be placed such that no energized, uninsulated, ungrounded busbar or terminal is exposed to inadvertent contact … while servicing load terminations in panelboards, switchboards, switchgear, or motor control centers supplied by feeder taps in 240.21(B) or transformer secondary conductors in 240.21(C) when the disconnecting device … is in the open position." (Not in the 2017 or 2020 on-disk text.)
• 215.18 (SPD for feeders) — NEW in 2023: (A)–(E) surge-protective-device block, including (E) "SPDs shall have a nominal discharge current rating (In) of not less than 10kA." (Not in the 2017 or 2020 on-disk text.)
• 215.12 (Identification) — unchanged in substance: the (A)/(B)/(C) structure and the dc "more than 60 volts" polarity-identification rules are present in all three editions (2023 keeps 60 V for ≤1000 V feeders; the over-1000-V mirror is 235.212, which uses 1500 V dc).

The edition history, verified line by line

Every section above was checked against the three on-disk sources — the 2017 full scan, the 2020 scan (which contains the complete Article 215 body), and the 2023 NEC CSV — by verify_art46.py (97 checks, all passing). The verifier normalizes line-wrap hyphenation, soft-hyphens, the disclosed OCR spots ("tts" for "its", "311.60" for "315.60", the 2020 "(l)"-for-"(1)" and "cunductors/grmerator/slwll" artifacts), and the 2017 page-footer text that intrudes into the scan, so only real wording changes survive. The result, pinned to editions:

• 2020 is the edition of the 600→1000 V migration and the ampacity-table renumber for the over-600-V feeder block: 215.2(B) heading "over 600" → "over 1000 Volts"; 310.15→310.14; 310.60→315.60; the 215.2(A) heading "Not More Than 600" → "Not More Than 1000 Volts"; 215.3 Exception 2 deleted; 215.9 de-limited; 215.10 Exception 3 (90 days) added; 215.6 reworded; 215.2(B)(3) gains its ampacity reference.
• 2023 is the edition of the relocation and relettering: the over-1000-V block leaves Article 215 for 235.202 (with (A)/(B)/(C)); 215.1 gains the "not over 1000 V ac / 1500 V dc" scope cap + the Art. 235 Info Note; 215.2 relettered ((A)(2)→(B) grounded, (A)(3)→(C) 55-A, lead reworded); 215.2(B) grounded-conductor reworded to "equipment grounding conductor size"; 215.3 drops "the provisions of"; 215.9 adds "listed"; 215.10 ceiling 600→1000 V + "This section" reword; NEW 215.15 (barriers) + 215.18 (SPD).
• Word-identical across all three editions: 235.202(A) (= 2017 215.2(B)(1), = 2020 215.2(B)(1)) the transformer-nameplate rule; 235.202(B) (= 215.2(B)(2)) the transformers-plus-125% rule; the 215.2(C) 55-A service rule; 235.205 (= 215.5) the diagram rule; 235.206 (= 215.6) the feeder EGC rule (modulo the 250.32(B)→250.32 reword).
• Every numeric value that could move, and which edition moved it: 600 V → 1000 V ceiling in 215.2(B) heading and 215.2(A) heading = 2020; the same 600→1000 V in 215.10 phase-to-phase = 2023 (note the asymmetry — the sizing-heading voltage moved two editions before the GFPE voltage did); 125% (235.202(B)) unchanged; 55 A (215.2(C)) unchanged; 10 kA (215.18(E)) NEW in 2023; 90 days (215.10 Exception 3) added 2020.
• Out of scope (2026 edition, 2024-cycle): not documented here; verify 215.2 / 235.202 / 215.10 / 215.18 against the adopted edition before relying on any single citation.

Worked examples (all computed by the shipped core under node)

Conductor picks from pickConductor31016 and breaker steps from nextStdBreaker in app.js (75 °C column). Transformer full-load current uses the standard nameplate formula I = kVA·1000 / (V·1.732). Every number below was produced by compute_art46.js under node — no hand math.

EX1 — 235.202(A): size from the sum of transformer nameplate ratings

EX2 — 235.202(B): the relocated 125% rule

EX3 — 235.202(C): the supervised route and its edition-pinned ampacity reference

EX4 — 215.2(C): the 55-A service-relative rule (renumbered from 215.2(A)(3))

EX5 — 215.2(B): the grounded-conductor floor per 250.122 (renumbered from 215.2(A)(2))

EX6 — 215.10: the 2023 600→1000 V delta in action

Gotchas

• Don't cross-cite across editions. "215.2(B)" (2017/2020) is "235.202" (2023). A 2017/2020 spec citing 215.2(B)(1)/(2)/(3) for an MV feeder translates to 235.202(A)/(B)/(C) in 2023. The reverse also holds: 235.202 has no 2017 section number — its substance is the 2017 215.2(B) block.
• The two 600→1000 V moves landed in different editions. The sizing-heading voltage (215.2(B) "over 600" → "over 1000 Volts") moved in 2020. The GFPE voltage (215.10 "not exceeding 600 V phase-to-phase" → "1000 V") moved in 2023. If you're updating a 1000/577 V design, check both: the conductors have been sized to the 1000 V rule since 2020, but the ground-fault-protection obligation only appeared in 2023.
• Ampacity tables changed in 2020, not 2023. 310.15/310.60 (2017) → 310.14/315.60 (2020 and 2023). If a 2017 calc references 310.15 or 310.60 for an over-1000-V feeder, re-run it against 310.14/315.60 — the table numbers for large conductors differ between the two table sets.
• 235.202(A) and (B) are word-identical to 2017 — but 235.202(C) is not. The transformer (A) and 125% (B) rules never changed. The supervised (C) route gained its "in accordance with 310.14(B) or 315.60(B)" ampacity anchor in 2020. Don't assume all three subsections are frozen.
• The 215.2 subsection letters moved in 2023. 2017/2020 215.2(A)(2) (grounded conductor) is 2023 215.2(B); 2017/2020 215.2(A)(3) (55-A rule) is 2023 215.2(C). A 2017 drawing citing "215.2(A)(3)" for the 55-A rule is now "215.2(C)".
• 215.15 and 215.18 are new by 2023, but the exact cycle isn't provable from the sources on disk. Both are absent from the 2017 and 2020 on-disk text, so I confirm they exist in 2023 and not earlier on disk — I do not claim which cycle (2020 or 2023) introduced them. The 2020 scan cuts off at 215.12.
• The AJB 2020 newsletter mis-quotes the deleted 215.3 Exception 2. It prints "Parts I through VIII … Part X" of Article 240; the actual 2017 print text (verified against the 2017 scan and the 2017 Article 240 part headings on disk) is "Parts I through VII … Part IX." Trust the on-disk print, not the secondary newsletter, for that citation.

The method, step by step

1. Determine whether the feeder is over 1000 V ac / 1500 V dc, nominal. If so, in the 2023 edition apply 235.202 (Article 235 Part III), not Article 215. If ≤1000 V, apply 215.2(A) (the math in the 215.2 ampacity article).
2. Translate any legacy 2017/2020 "215.2(B)" citations to 2023 "235.202" using the relocation map above.
3. Size the conductors per 235.202: (A) sum of transformer nameplate ratings (transformers only); (B) nameplate ratings + 125% of simultaneously-operated utilization; or (C) qualified persons under engineering supervision (anchored to 310.14(B)/315.60(B) since 2020). Use the 315.60 ampacity table (310.14 where applicable).
4. Size the grounded conductor ≥ 250.122 (250.122(F) parallel exception applies).
5. Provide overcurrent protection per 235.203 (over-1000-V) / 215.3 (≤1000 V) — 125% of continuous load.
6. Apply 215.10 ground-fault protection of equipment where the disconnect is ≥1000 A on a >150 V-to-ground wye ≤1000 V phase-to-phase (2023 ceiling; 600 V in 2017/2020) per 230.95.
7. Apply the 55-A rule (215.2(C)) where a ≤55 A service carries the total feeder load.
8. Verify against the adopted edition in your jurisdiction (2017/2020/2023 documented here; 2026 changes out of scope).

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