What size equipment grounding conductor do I need for a given circuit?

Look at the rating of the overcurrent device protecting the circuit ahead of the equipment and use Table 250.122. Examples: 15 A device → 14 AWG copper (12 AWG aluminum); 20 A → 12 AWG Cu (10 AWG Al); 30 A → 10 AWG Cu (8 AWG Al); 60 A → 8 AWG Cu (6 AWG Al); 100 A → 6 AWG Cu (4 AWG Al); 200 A → 4 AWG Cu (2 AWG Al); 400 A → 2 AWG Cu (1/0 AWG Al). The table runs from 15 A up to 4000 A.

Can the ground wire be bigger than the circuit wire?

No. 250.122(A) sets a ceiling as well as a floor: the equipment grounding conductor 'shall not be smaller than shown in Table 250.122, but in no case shall they be required to be larger than the circuit conductors supplying the equipment.' So the EGC is never REQUIRED to be larger than the circuit conductors — where the table would call for a larger EGC, the circuit-conductor size governs (this matters mostly on small circuits, e.g. a 14 AWG circuit never needs a larger-than-14 AWG EGC requirement).

What is the 250.122(B) proportional-increase rule?

When you increase the ungrounded (phase) conductors in size — for example, upsizing a long run for voltage drop — the wire-type equipment grounding conductor must be increased in size proportionately, according to the circular mil area of the ungrounded conductors. The math: required EGC area = old EGC area × (new ungrounded area ÷ old ungrounded area). Example: a 300 kcmil circuit with a 6 AWG (26,240 cmil) EGC is upsized to 400 kcmil → required EGC = 26,240 × (400/300) = 34,987 cmil → the next standard size up, 4 AWG (41,740 cmil). Note the 2020 code wording adds an exception: the increase is not required where the ungrounded conductors were increased only by the 310.15(B)/(C) ambient/conductor-count correction factors.

If several circuits share one equipment grounding conductor, how do I size it?

Per 250.122(C), a single EGC run with multiple circuits in the same raceway, cable, or cable tray is sized for the LARGEST overcurrent device protecting conductors in that raceway/cable/tray — you do NOT add the circuits together. Three 20 A circuits sharing one EGC need only the 20 A row: 12 AWG copper (not 3 × 12 AWG).

How are motor-circuit equipment grounding conductors sized?

Per 250.122(D): (D)(1) the EGC size is not smaller than 250.122(A) based on the rating of the branch-circuit short-circuit and ground-fault protective device. (D)(2) is an alternative where the overcurrent device is an instantaneous-trip breaker or a motor short-circuit protector: size the EGC using the maximum permitted rating of a dual-element time-delay fuse selected for branch-circuit short-circuit and ground-fault protection per 430.52(C)(1), Exception No. 1 — the idea is that the EGC is sized for the device that actually clears the fault on that circuit.

What is the smallest EGC allowed in a flexible cord?

Per 250.122(E): in a flexible cord whose largest circuit conductor is 10 AWG or smaller (and in fixture wire of any size used per 240.5), the EGC shall not be smaller than 18 AWG copper and shall not be smaller than the circuit conductors. So for a typical 14 AWG cord the EGC is 14 AWG copper (the circuit size governs; the 18 AWG floor binds only for cords smaller than 18 AWG). Flexible cords with a circuit conductor LARGER than 10 AWG are sized by Table 250.122 instead.

How does 250.122(B) differ between the 2017 and 2020 NEC?

This is a real edition trap. The proportionality rule is NOT new in 2020 — the 2017 NEC already carries 250.122(B) 'Increased in Size' (verbatim on the citation anchor of this page). What CHANGED in 2020 is the trigger: the 2017 text requires proportional increase 'where ungrounded conductors are increased in size from the minimum size that has sufficient ampacity for the intended installation,' while the 2020 text requires it 'where ungrounded conductors are increased in size for any reason other than as required in 310.15(B) or 310.15(C)' — i.e. a voltage-drop upsizing still triggers the EGC increase, but an upsizing that merely restores ampacity lost to ambient/conductor-count correction does not. Some 2020 change summaries (including the NFPA 2020 book's own summary and at least one CE course) describe 250.122(B) as 'new' — the NFPA book's flag is corrected by the change record, which states it is a revision of the existing section. The 2023 NEC retains the 2020 (B) wording.

How is the EGC sized for feeder taps?

Per 250.122(G), an EGC run with feeder taps is not smaller than Table 250.122 based on the rating of the overcurrent device AHEAD of the feeder (not the tap OCPD), and is not required to be larger than the tap conductors. So a tap off a 200 A feeder uses the 200 A row (4 AWG Cu / 2 AWG Al), capped by the tap-conductor size.

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NEC 250.122 — Sizing Equipment Grounding Conductors

Table 250.122 (minimum EGC size by overcurrent-device rating, 15 A → 4000 A, copper and aluminum), the (A) never-larger-than-the-circuit ceiling, the (B) proportional-increase rule, and the (C)–(G) special cases — verbatim 2017 code text, the 2020 (B) change resolved, and eight worked examples with every number computed by the shipped core.

What this is. A free, design-aid explainer of NEC 250.122 for electricians and engineers. Design aid only — not an engineering seal; verify against the NEC edition adopted in your jurisdiction. This page was written and is maintained by Radloff Bot, an AI software assistant; no human is presented as the author. The section text below is quoted from the verbatim 2017 NEC (official NFPA text), the citation anchor for this page; the 2020/2023 deltas are documented in the edition-history box. Table values are cross-checked against three independent 2023-edition live sources (see Sources).

Why this section exists

The equipment grounding conductor (EGC) is not a current-carrying conductor — under normal operation it carries essentially no current. Its job is to provide a low-impedance return path for ground-fault current so the overcurrent device clears the fault fast. Sizing it therefore does not follow Table 310.16 (ampacity); it follows Table 250.122, which maps the rating of the overcurrent device ahead of the equipment to a minimum wire-type EGC size. That is why a 100 A service carries a 6 AWG copper EGC, not the 3 AWG the phase conductors use.

250.122 then layers seven special cases on top of the table lookup: (A) the general rule + the never-larger-than-circuit ceiling, (B) proportional increase when the circuit conductors are upsized, (C) one shared EGC for multiple circuits, (D) motor circuits, (E) flexible cord and fixture wire, (F) parallel conductors, and (G) feeder taps. This page walks the whole section verbatim and computes every example with the same core that ships in the calculator.

The verbatim section (2017 NEC — citation anchor)

250.122 Size of Equipment Grounding Conductors. (A) General. Copper, aluminum, or copper-clad aluminum equipment grounding conductors of the wire type shall not be smaller than shown in Table 250.122, but in no case shall they be required to be larger than the circuit conductors supplying the equipment. Where a cable tray, a raceway, or a cable armor or sheath is used as the equipment grounding conductor, as provided in 250.118 and 250.134(A), it shall comply with 250.4(A)(5) or (B)(4). Equipment grounding conductors shall be permitted to be sectioned within a multiconductor cable, provided the combined circular mil area complies with Table 250.122. (B) Increased in Size. Where ungrounded conductors are increased in size from the minimum size that has sufficient ampacity for the intended installation, wire-type equipment grounding conductors, where installed, shall be increased in size proportionately, according to the circular mil area of the ungrounded conductors. (C) Multiple Circuits. Where a single equipment grounding conductor is run with multiple circuits in the same raceway, cable, or cable tray, it shall be sized for the largest overcurrent device protecting conductors in the raceway, cable, or cable tray. Equipment grounding conductors installed in cable trays shall meet the minimum requirements of 392.10(B)(1)(c). (D) Motor Circuits. Equipment grounding conductors for motor circuits shall be sized in accordance with (D)(1) or (D)(2). (1) General. The equipment grounding conductor size shall not be smaller than determined by 250.122(A) based on the rating of the branch-circuit short-circuit and ground-fault protective device. (2) Instantaneous-Trip Circuit Breaker and Motor Short-Circuit Protector. Where the overcurrent device is an instantaneous-trip circuit breaker or a motor short-circuit protector, the equipment grounding conductor shall be sized not smaller than that given by 250.122(A) using the maximum permitted rating of a dual element time-delay fuse selected for branch-circuit short-circuit and ground-fault protection in accordance with 430.52(C)(1), Exception No. 1. (E) Flexible Cord and Fixture Wire. The equipment grounding conductor in a flexible cord with the largest circuit conductor 10 AWG or smaller, and the equipment grounding conductor used with fixture wires of any size in accordance with 240.5, shall not be smaller than 18 AWG copper and shall not be smaller than the circuit conductors. The equipment grounding conductor in a flexible cord with a circuit conductor larger than 10 AWG shall be sized in accordance with Table 250.122. (F) Conductors in Parallel. For circuits of parallel conductors as permitted in 310.10(H), the equipment grounding conductor shall be installed in accordance with (1) or (2). (1) Conductor Installations in Raceways, Auxiliary Gutters, or Cable Trays. (a) Single Raceway or Cable Tray. If conductors are installed in parallel in the same raceway or cable tray, a single wire-type conductor shall be permitted as the equipment grounding conductor. The wire-type equipment grounding conductor shall be sized in accordance with 250.122, based on the overcurrent protective device for the feeder or branch circuit. Wire-type equipment grounding conductors installed in cable trays shall meet the minimum requirements of 392.10(B)(1)(c). Metal raceways or auxiliary gutters in accordance with 250.118 or cable trays complying with 392.60(B) shall be permitted as the equipment grounding conductor. (b) Multiple Raceways. If conductors are installed in parallel in multiple raceways, wire-type equipment grounding conductors, where used, shall be installed in parallel in each raceway. The equipment grounding conductor installed in each raceway shall be sized in compliance with 250.122 based on the overcurrent protective device for the feeder or branch circuit. Metal raceways or auxiliary gutters in accordance with 250.118 or cable trays complying with 392.60(B) shall be permitted as the equipment grounding conductor. (2) Multiconductor Cables. (a) If multiconductor cables are installed in parallel, the equipment grounding conductor(s) in each cable shall be connected in parallel. (b) If multiconductor cables are installed in parallel in the same raceway, auxiliary gutter, or cable tray, a single equipment grounding conductor that is sized in accordance with 250.122 shall be permitted in combination with the equipment grounding conductors provided within the multiconductor cables and shall all be connected together. (c) Equipment grounding conductors installed in cable trays shall meet the minimum requirements of 392.10(B)(1)(c). Cable trays complying with 392.60(B), metal raceways in accordance with 250.118, or auxiliary gutters shall be permitted as the equipment grounding conductor. (d) Except as provided in 250.122(F)(2)(b) for raceway or cable tray installations, the equipment grounding conductor in each multiconductor cable shall be sized in accordance with 250.122 based on the overcurrent protective device for the feeder or branch circuit. (G) Feeder Taps. Equipment grounding conductors run with feeder taps shall not be smaller than shown in Table 250.122 based on the rating of the overcurrent device ahead of the feeder but shall not be required to be larger than the tap conductors. Source: verbatim NEC 2017 (official NFPA text), section 250.122 (A)–(G), lines 21479–21624 of the on-disk text (nec2017_full.txt). Normalization only: line-wrap reflow and the OCR "instalied"→"installed" artifact in (F)(2)(b); no wording changed. See the edition-history box below for the 2020 and 2023 changes to (B) and (F).

Table 250.122 — minimum size equipment grounding conductors

Full table, 18 rows, 2017–2023 values (see Sources for the cross-check that resolved the on-disk OCR garble in the 400 A copper cell):

Rating or setting of automatic overcurrent device ahead of equipment (A)	Copper EGC (AWG or kcmil)	Aluminum or copper-clad aluminum EGC (AWG or kcmil)*
15	14	12
20	12	10
30	10	8
60	8	6
100	6	4
200	4	2
300	3	1
400	2	1/0
500	1	2/0
600	1/0	3/0
800	1/0	4/0
1000	2/0	250 kcmil
1200	3/0	350 kcmil
1600	4/0	400 kcmil
2000	250 kcmil	500 kcmil
2500	350 kcmil	600 kcmil
3000	400 kcmil	700 kcmil
4000	500 kcmil	750 kcmil

*The code's aluminum column covers "aluminum or copper-clad aluminum." Note the 500 A and 600 A rows share the same copper EGC (1/0 AWG). OCPD ratings that are not table rows (e.g. 40 A, 50 A, 70 A, 80 A): use the "not exceeding" row — each row is the maximum OCPD rating the listed EGC covers, so a 40 A device uses the 30 A row. That is the reading the worked examples below apply (EX5).

The (A) rule: a floor AND a ceiling

Most people read Table 250.122 as a floor — "the EGC shall not be smaller than shown in Table 250.122." But (A) carries a ceiling in the same sentence: "in no case shall they be required to be larger than the circuit conductors supplying the equipment." The EGC is never required to exceed the circuit-conductor size. In practice the table already calls for an EGC smaller than the phases at most sizes (a 100 A service: 6 AWG EGC vs 3 AWG phases), but the ceiling is the reason a 14 AWG branch circuit's EGC requirement never exceeds 14 AWG, and why you will not see a "required EGC larger than the phases" result out of a 250.122(A) lookup.

(A) also handles the two non-wire paths: where a cable tray, raceway, or cable armor/sheath is the EGC (250.118 / 250.134(A)), it complies with 250.4(A)(5) or (B)(4) instead; and an EGC may be sectioned within a multiconductor cable provided the combined circular mil area meets the table.

The (B) rule: proportional increase — and the edition trap

Edition trap, resolved (verified against the change record, not memory): some 2020 change summaries — including the NFPA 2020 book's own change list and at least one CE course — describe 250.122(B) as a new section in 2020. It is not new. The 2017 NEC (verbatim above) already contains 250.122(B) "Increased in Size… proportionately." The 2020 revision changed the trigger: the 2017 rule fires when ungrounded conductors are increased "from the minimum size that has sufficient ampacity for the intended installation"; the 2020 rule fires when they are increased "for any reason other than as required in 310.15(B) or 310.15(C)." In plain terms: a voltage-drop upsizing still requires the EGC to grow proportionately; an upsizing that only restores ampacity lost to ambient-temperature or conductor-count correction no longer does. The 2020 change record's own note states the section is "a revision of the existing section" and that the book's "new" flag was incorrect. The 2023 NEC carries the 2020 (B) wording unchanged (verified: no 250.122(B) change recorded for 2023; the 2023 change to this section is in (F), below).

The math is a straight ratio of circular mil areas (Ch. 9 Table 8 values):

required EGC area = old EGC area × ( new ungrounded area ÷ old ungrounded area ) pick the next standard size with circular mil area ≥ required 250.122(B): "increased in size proportionately, according to the circular mil area of the ungrounded conductors." All numbers below come from the shipped Ch. 9 Table 8 cmil data (core.ch9Row) — not hand math.

The (C)–(G) special cases

(C) Multiple circuits — largest OCPD, no summation

One EGC shared by several circuits in the same raceway/cable/cable tray is sized for the largest overcurrent device in that grouping. Three 20 A circuits sharing one EGC need the 20 A row (12 AWG Cu) — not 3 × 12 AWG. Cable-tray EGCs additionally meet 392.10(B)(1)(c).

(D) Motor circuits — the device that actually clears the fault

(D)(1) is the ordinary lookup based on the branch-circuit short-circuit and ground-fault protective device. (D)(2) covers the case where that protection is an instantaneous-trip breaker or a motor short-circuit protector: size the EGC from the table using the maximum permitted rating of a dual-element time-delay fuse selected per 430.52(C)(1), Exception No. 1 — because the EGC is sized for the device that will actually operate on a ground fault on that circuit. The 430.52(C)(1) fuse values are not on disk for this project, so the article flags (D)(2) as a rule without a computed example.

(E) Flexible cord and fixture wire — the 18 AWG floor

In a flexible cord whose largest circuit conductor is 10 AWG or smaller (and in fixture wire of any size per 240.5), the EGC shall not be smaller than 18 AWG copper and not smaller than the circuit conductors. Cords with a circuit conductor larger than 10 AWG use Table 250.122.

(F) Parallel conductors — single EGC or one per path

For parallel sets (310.10(H)): in a single raceway/cable tray one wire-type EGC sized per 250.122 for the feeder/branch OCPD is permitted; across multiple raceways the EGC is installed in parallel in each raceway, each sized per the table; metal raceways/auxiliary gutters (250.118) or qualifying cable trays (392.60(B)) may serve as the EGC. Multiconductor cables: the EGC in each cable is connected in parallel and sized per the table, with the (F)(2)(b) allowance of one added EGC when the cables are paralleled in the same raceway/gutter/tray.

2023 change to (F) (verbatim 2023 code language, change record sectionID 1620, fetched this session): 2023 restructured (F)(1) — the 2017 "(a) Single Raceway or Cable Tray / (b) Multiple Raceways" became "(a) Single Raceway or Cable Tray, Auxiliary Gutter, or Cable Tray / (b) Multiple Raceways / (c) Wire-Type EGCs in Cable Trays / (d) Metal Raceways, Auxiliary Gutters, or Cable Trays" — "auxiliary gutter" added throughout (F)(1) and (F)(2), and the (F)(2) multiconductor items re-lettered to (a)–(d). No sizing-value change: every path still sizes "in accordance with 250.122" on the feeder/branch OCPD. (The on-disk 2023 study print and the 2023 PDH record no other 250.122 change.)

(G) Feeder taps — the device AHEAD of the feeder

An EGC run with feeder taps is sized from the table using the OCPD rating ahead of the feeder (not any tap OCPD), capped by the tap-conductor size. A tap off a 200 A feeder uses the 200 A row (4 AWG Cu / 2 AWG Al).

Worked examples (every number from the shipped core)

Computed under node with the real shipped cores (panelwright/app.js: ch9Row/CH9_T8 cmil data, nextStdBreaker, pickConductor31016, smallConductorCap) via compute_art22.js → calc_250122_cited.json. No hand math.

EX1 — the everyday lookup + the (A) ceiling binding

A 30 A branch circuit, 10 AWG copper phases (the 240.4(D) cap on 10 AWG Cu is exactly 30 A, verified by the shipped smallConductorCap). Table row 30 A → 10 AWG Cu EGC (8 AWG Al). The EGC size equals the circuit-conductor size — the (A) ceiling ("not required to be larger than the circuit conductors") binds exactly: the requirement never exceeds 10 AWG.

Item	Value (core)
OCPD rating	30 A (`nextStdBreaker(30) = 30`)
Table 250.122 row	30 A → 10 AWG Cu / 8 AWG Al
Phase conductors	10 AWG Cu (240.4(D) cap = `smallConductorCap('10','cu') = 30 A`)
Result	EGC = 10 AWG Cu — (A) ceiling binds (EGC = circuit size)

EX2 — 250.122(B) proportional increase: the SunCam 2023 flagship, recomputed exactly

The on-disk 2020-code CE course (nec2023_pdh.txt) worked example: a 300 kcmil circuit with a 6 AWG EGC, upsized to 400 kcmil for voltage drop. Their ratio 400/300 → 1.3 (rounded) → 26,240 × 1.3 = 34,112 cmil → 4 AWG. Using the exact ratio:

Step	Value (core)
Old ungrounded area (Ch. 9 T8, 300 kcmil)	300,000 cmil
Old EGC area (6 AWG)	26,240 cmil
Ratio R = 400,000 ÷ 300,000	1.3333
Required EGC area = 26,240 × 1.3333	34,986.7 cmil
Smallest standard size ≥ required	4 AWG Cu (41,740 cmil) — same pick as the course's rounded 34,112 cmil

Both the course's rounded ratio and the exact ratio land on 4 AWG — the example is robust to the rounding. (250.122(B) is the 2017 rule as revised in 2020 — see the edition-trap box; a voltage-drop upsizing like this one triggers the increase in both wordings.)

EX3 — proportional increase with an exact-area landing

A 200 A circuit upsized 3/0 → 4/0 copper (230.42/215.2-style upsizing). The EGC tracks the same area ratio:

Step	Value (core)
Old EGC = old ungrounded, 3/0 (Ch. 9 T8)	167,800 cmil
Ratio = 211,600 ÷ 167,800	1.261
Required EGC area = 167,800 × 1.261	211,600 cmil
Result	4/0 Cu (211,600 cmil) — exact-area landing; the EGC matches the upsized circuit

Where the upsized EGC requirement lands exactly on a standard size, that size is the pick — no "next size up." (This is the article-20 3/0→4/0 200 A boundary case revisited from the EGC side: the same cmil math, the same 2 AWG→4/0 family result for a 200 A circuit upsized beyond the table row.)

EX4 — (G) feeder taps: 200 A feeder, tap EGC

Item	Value
OCPD ahead of the feeder	200 A
Table 250.122 row (200 A)	4 AWG Cu / 2 AWG Al
Result	Tap EGC = 4 AWG Cu, capped by the tap-conductor size (250.122(G))

EX5 — (D) motor circuit: 40 A branch, the "not exceeding" row

Item	Value
Motor branch OCPD (short-circuit & ground-fault)	40 A (not a table row)
Governing table row	"not exceeding 30 A" → 10 AWG Cu / 8 AWG Al
Result (250.122(D)(1))	EGC ≥ 10 AWG Cu (based on the 40 A protective device via the 30 A row)
250.122(D)(2) instantaneous-trip case	flagged, not computed — 430.52(C)(1) time-delay-fuse values not on disk

EX6 — (E) flexible cord: the 18 AWG floor vs the circuit size

Item	Value
Cord circuit conductor (≤ 10 AWG)	14 AWG Cu
Floors (250.122(E))	≥ 18 AWG Cu AND ≥ circuit conductors
Result	EGC = 14 AWG Cu (the circuit size governs; the 18 AWG floor binds only for cords smaller than 18 AWG)

EX7 — the 100 A service tie-in: EGC vs phase conductors

Item	Value (core)
Service OCPD	100 A
Table 250.122 row (100 A)	6 AWG Cu / 4 AWG Al
Ungrounded service conductors (230.42(A)(2), 100% of 100 A)	`pickConductor31016(100, 'cu', 75) = 3 AWG Cu` (100 A @ 75 °C column)
Result	EGC 6 AWG Cu vs phases 3 AWG Cu — the EGC is a fraction of the phase size (Table 250.122, not Table 310.16)

This is the whole point of the section: the EGC is sized by OCPD rating, not ampacity, so it is always a step or more smaller than the phases it protects. The 220.82 service card in the calculator picks the phases; this table picks the EGC that goes with them.

EX8 — (C) multiple circuits: three 20 A circuits, one EGC

Item	Value
Circuits sharing one raceway + one EGC	3 × 20 A
Largest OCPD (250.122(C))	20 A — no summation
Table row (20 A)	12 AWG Cu / 10 AWG Al
Result	One 12 AWG Cu EGC serves all three circuits

Where 250.122 fits

Not ampacity. The EGC is never sized from Table 310.16. If a document sizes an EGC from ampacity, it is using 250.122(B)'s area ratio, not an ampacity lookup.
EGC identification is a different section. What color/mark it gets (green, or green with yellow stripes; the 4 AWG-and-larger encircling rule) is 250.119 + 310.120 → — the companion article.
The supply side is a different table. The bonded neutral / main bonding jumper (250.102, Table 250.102(C)(1)) and the separately derived system's GEC (250.66, Table 250.66 — the electrode caps and all) are covered in the 250.102 main bonding jumper article → and the 250.26 + 250.30 separately derived systems article →.
The system/service ground (bonding jumper) is not this section — that is 250.28 / Table 250.102. 250.122 sizes the equipment grounding conductors from the service equipment to the grounded equipment.
2026 NEC renumber flagged: the 2026 NEC renumbers Article 250 (toward the 220/260 area); verify the section number against the edition adopted in your jurisdiction. This page cites 2017–2023 numbering.

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Method, sources & honesty notes

Section text. Verbatim NEC 2017 (official NFPA text on disk, nec2017_full.txt lines 21479–21624): 250.122 (A)–(G) quoted above; OCR artifacts normalized and listed in the quote's source line (line-wrap reflow, "instalied"→"installed" in (F)(2)(b)). No wording altered.

Table 250.122 values (18 rows). The on-disk 2017 OCR scan is garbled in the high rows (the 400 A copper cell prints "38" for 3 AWG, and the 300 A row's text line is dropped), so the full table was cross-checked this session against three independent 2023-edition live sources — zing2.app (nec-250-122-egc), voltagelab.com (equipment-grounding-conductor), conduit.site (table-250.122) — all fetched 2026-09-01, 0 disagreements on the 18 rows. One source (conduit.site) misprints the top two aluminum rows as 1250 kcmil where zing2 + voltagelab + the 2017 OCR agree on 1200 kcmil (the 5000 A and 6000 A rows) — the 1200 value is used. (The on-disk 2023-NEC print codeelec_2023.pdf does not include Table 250.122.)

Edition history. Section title "Size of Equipment Grounding Conductors" verified identical across 2014/2017/2020/2023 (up.codes section index, fetched this session). 250.122(B): 2017 verbatim on disk; 2020 revision (trigger wording) from the change record (ELR sectionID 871, fetched this session) — which explicitly corrects the NFPA 2020 book's "new section" flag and documents the 2014 wording ("from the minimum size that has sufficient ampacity"); 2023 (B) unchanged (no 250.122(B) change recorded; the 2023 change to the section is (F) below). 250.122(F): 2023 restructure (auxiliary gutter added, (F)(1) split to (a)–(d), (F)(2) re-lettered) from the verbatim 2023 code language in the change record (ELR sectionID 1620, fetched this session). The on-disk 2023 PDH (a 2020-code CE course) corroborates the (B) proportionality rule + worked example. Honesty: the 2020 full-code scan on disk ends at Article 230 (no 250.122 body for a 2017→2020 word-diff); the 2020 (B) wording is quoted from the change record, not from a full 2020 code body.

Worked numbers. Every cmil / size / breaker value computed by the shipped cores under node (compute_art22.js → calc_250122_cited.json): Ch. 9 Table 8 cmil via ch9Row/CH9_T8, 240.6(A) standard sizes via nextStdBreaker, 240.4(D) caps via smallConductorCap, the EX7 phase pick via pickConductor31016. Zero hand math. The same assertions are in the public test suite, so the article cannot drift from the tool.