NEC 430.22 + 430.52 — Single-Motor Branch-Circuit Conductors & OCPD

How to size the conductors and the overcurrent protective device for a single-motor branch circuit — 430.22 (conductors at 125% of the full-load current, with the wye-start 72% and part-winding 62.5% controller-side reductions), 430.52 + Table 430.52 (the OCPD percentage table and the starting-current increases), 430.6(A)(1) (where the full-load current comes from), and the 240.4(D)/(G) interaction that makes a 30 A breaker on 14 AWG legal for a motor. Verbatim 2017 and 2023, the verified edition deltas, and six worked examples — every number computed by the shipped calculator core. Last updated 2026-09-04 (written for PanelWright v1.16).

What these two sections are (and the one job they do together)

Article 430 protects motors. Two sections do almost all of the everyday single-motor branch-circuit work, and they answer two different questions that people constantly mix up:

• 430.22 — "How big are the WIREs?" Conductors that supply a single motor used in a continuous duty application shall have an ampacity of not less than 125 percent of the motor full-load current rating, as determined by 430.6(A)(1). This is a CONDUCTOR rule: it sets the minimum ampacity of the ungrounded conductors (and the grounded conductor, which for a single motor is sized the same per 310.12). It is NOT about the breaker.
• 430.52 — "How big is the BREAKER (or fuse)?" The motor branch-circuit short-circuit and ground-fault protective device shall comply with 430.52(B) (capable of carrying the starting current) and with a table of percentages — Table 430.52 — of the motor full-load current: 250% inverse-time breaker, 175% time-delay fuse, 300% nontime-delay fuse, 800% instantaneous trip. This is the OCPD rule, and it is deliberately much looser than the wire rule because a motor draws 5–8× its running current while starting.

Both rules key off the same number — the motor full-load current (FLC) — but 430.6(A)(1) says that number comes from the code tables (Table 430.248 single-phase, Table 430.250 three-phase), not the nameplate. That one fact is the root of most motor-sizing errors: people use the nameplate amps, or they size the wire and the breaker on the same percentage, or they apply 240.4(D)'s small-conductor caps to a motor circuit (they don't apply — 240.4(G) sends motor conductors to Article 430). This article covers 430.22(A)–(G), 430.52(A)–(D) with Table 430.52, 430.6(A)(1), and the 240.4(D)/(G) interaction across the editions on disk, with six worked examples computed by the shipped core.

First: where the full-load current comes from (430.6(A)(1))

2017 (verbatim on disk)

The sentence that matters: "the values given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250 shall be used … instead of the actual current rating marked on the motor nameplate." For the two everyday cases: Table 430.248 gives full-load currents of single-phase ac motors; Table 430.250 gives full-load currents of three-phase ac motors. (430.247 is dc motors; 430.249 is the single-phase table's companion for motors marked in amperes — the four tables together cover every general motor application.)

Two small corrections people need to hear:

• Table values, not nameplate. A 5 hp, 230 V, 3-phase motor nameplate may read "14.5 A" or "15.5 A" — irrelevant for conductor and OCPD sizing. Table 430.250 says 15.2 A, and that is the number 430.22 and 430.52 use. (The nameplate current IS used for one thing: separate overload protection, 430.6(A)(2) / 430.32 — a different section, a different device.)
• The nameplate wins only for low-speed (<1200 RPM), high-torque, and multispeed motors, because their FLC genuinely varies from the table's typical belted-motor values.

The FLC tables the examples use (live-verified values, because the on-disk 2017 scan of these tables is OCR-garbled — see the method box):

430.22 — Single Motor: the conductor rule (A)–(G)

2017 (verbatim on disk)

Break the section down:

1. The general rule (the lead sentence): continuous-duty single motor → conductor ampacity ≥ 125% of the FLC (per 430.6(A)(1)). "125% of the FLC" is the whole of motor branch-circuit conductor sizing for the ordinary case — EX1 and EX2 apply it.
2. (A) DC motor-rectifier supplied: on the input of the rectifier, 125% of the rated input current to the rectifier; between the rectifier and the motor, 190% (single-phase half-wave) or 150% (single-phase full-wave) of the motor FLC. DC-rectifier motors are uncommon in the field, but the 190/150 values appear on exams.
3. (B) Multispeed: line-side conductors based on the highest nameplate FLC of any speed; controller-to-motor conductors at 125% of the FLC of the winding(s) they energize. Note the multispeed exception to 430.6(A)(1): multispeed motors use nameplate values (the tables can't hold a FLC that varies with speed).
4. (C) Wye-start, delta-run: line side 125% FLC; controller-to-motor 72% FLC. The Informational Note explains where 72 comes from: the individual motor circuit conductors of a wye-start motor carry 58% of the rated load current, and 58% × 125% = 72%. EX4 applies it.
5. (D) Part-winding: line side 125% FLC; controller-to-motor 62.5% FLC (50% per winding × 125%). A part-winding motor is a single-phase motor that starts on one winding and then connects the second in parallel — the second winding only runs once the first is up to speed, so the controller-to-motor conductors see half. EX5 applies it.
6. (E) Other than continuous duty: short-time, intermittent, periodic, or varying duty → ampacity per Table 430.22(E) (the duty-cycle table, below) of the nameplate current. Note: this is the one 430.22 subsection that sizes on the nameplate, not the table FLC.
7. (F) Separate terminal enclosure: a stationary motor rated 1 hp or less with a separate terminal enclosure (430.245(B)) may use conductors smaller than 14 AWG, down to 18 AWG, provided they have the 430.22 ampacity.
8. (G) Conductors for small motors: the 14 AWG floor, with the 18 AWG and 16 AWG copper exceptions. The 18 AWG copper circuit is allowed when the motor FLC is greater than 3.5 A and ≤ 5 A (with 430.52 protection + max Class 10/10A overload per 430.32 + 240.4(D)(1)(2) OCPD), or ≤ 3.5 A (with 430.52 protection + max Class 20 overload + 240.4(D)(1)(2) OCPD). The 16 AWG copper circuit is allowed for FLC greater than 5.5 A and ≤ 8 A (Class 10/10A overload, 240.4(D)(2)(2) OCPD) or ≤ 5.5 A (Class 20 overload, 240.4(D)(2)(2) OCPD). This is the "small motors in appliance-like circuits" provision — and it is where 240.4(D)'s small-conductor OCPD rules legitimately reappear for motors.

Table 430.22(E) — Duty-Cycle Service (2017, verbatim on disk)

The duty-cycle table is the other-than-continuous-duty path: the conductor ampacity is a percentage of the nameplate current (not the table FLC), picked from the row for the duty classification and the column for how the nameplate current is rated. The Note sets the default: if you can't clearly show the motor doesn't operate continuously under any condition of use, it is continuous duty and the 125% rule applies.

430.52 — Rating or Setting for Individual Motor Circuit: the OCPD rule (A)–(D)

2017 (verbatim on disk)

How 430.52 actually works, in order:

1. (A) is the routing rule: the OCPD must satisfy (B) — capable of carrying the starting current — AND either (C) (the percentage table path, which is 99% of installations) or (D) (torque motors, nameplate per 240.4(B)).
2. (B) is the physical rule: whatever number the table gives, the device must physically carry the starting inrush without clearing. A breaker that the table allows but that the motor's locked-rotor/inrush current would open is not a compliant device for that motor — this is why Exception No. 2 (the increase path) exists, and why a controller's overload relay table can cap the OCPD lower (C)(2).
3. (C)(1) is the table path: pick the row for the motor type, the column for the device type, multiply by the FLC. Exception No. 1 rounds UP to the next standard ampere rating (240.6) when the product doesn't land on a standard size — this is the "next standard size" step, and it is the ONLY time you round the OCPD up; you never round the product down. Exception No. 2 is the starting-current increase: if the table value (or the Exception No. 1 rounded value) still won't carry the starting current, you may increase to 400% (nontime-delay fuse ≤600 A or time-delay Class CC fuse), 225% (time-delay/dual-element fuse), 400% or 300% (inverse-time breaker, split at 100 A FLC), or 300% (601–6000 A class fuse) — those are the MAXIMUMS, and you only go as far as the starting current requires.
4. (C)(2) caps it: the manufacturer's overload relay table (the one printed on the starter/controller listing) wins when it specifies maximum OCPD ratings — "shall not be exceeded even if higher values are allowed as shown above." In practice this is often the binding limit, because a listed combination controller is engineered around a specific OCPD range.
5. (C)(3) is the instantaneous-trip (MCP) path: 800% of FLC (Design B: 1100%), only in a listed combination controller, only if adjustable; the increases run to 1300%/1700%.
6. (C)(4)–(C)(7) handle multispeed motors (smallest-winding rule, with the highest-current-winding Exception), semiconductor fuses for solid-state controllers, self-protected combination controllers, and motor short-circuit protectors — all "in lieu of Table 430.52" paths with their own caps.

Table 430.52 — Maximum Rating or Setting of Motor Branch-Circuit Short-Circuit and Ground-Fault Protective Devices (2017, verbatim on disk)

Read the table the way you would in the field:

• Almost every common motor is 300 / 175 / 800 / 250 — single-phase, AC polyphase, standard squirrel-cage, synchronous. The only common row that differs is Design B energy-efficient: the instantaneous-trip value jumps from 800% to 1100% (the higher-energy Design B motors need more inrush margin), and wound-rotor and DC constant-voltage motors run 150 / 150 / 800 / 150 (and 250 instantaneous for DC).
• The columns are the device: nontime-delay fuse (which also covers time-delay Class CC fuses), dual-element (time-delay) fuse, instantaneous-trip breaker, inverse-time breaker. If you don't know which column, you don't know which device — a 40 A inverse-time breaker is a different animal from a 40 A nontime-delay fuse on the same motor (250% vs 300% of FLC).
• The inverse-time column also covers nonadjustable inverse-time breakers (Note 2) — i.e. the ordinary molded-case motor-circuit breaker — and those may be "modified" (increased) per 430.52(C)(1) Exceptions No. 1 and 2.
• The 200% note for low-torque synchronous motors (usually ≤450 rpm, starting unloaded, on compressors/pumps) is a relaxation, not a rule: such a motor "does not require" more than 200% — the table value still applies as the maximum, the note says the motor won't need to use it.

The 240.4(D) / 240.4(G) interaction: why the breaker can exceed the wire

240.4 is the general overcurrent-protection article, and 240.4(D) caps the OCPD for small conductors at their ampacity — 15 A for 14 AWG Cu, 20 A for 12 AWG Cu, 30 A for 10 AWG Cu. A naive reading says "a 30 A breaker on 14 AWG Cu is a violation." For a motor, it is not. Here is why, verbatim:

240.4(D) — 2017 (verbatim on disk)

240.4(G) — the sentence that changes everything

So the chain is: 240.4(D) caps small-conductor OCPDs "unless specifically permitted in 240.4(E) or (G)" → 240.4(G) says specific conductors (including motor and motor-control circuit conductors) get their OCPD "as referenced in Table 240.4(G)" → the table sends motor conductors to Article 430, Parts II, IV, and VII (the branch-circuit short-circuit/ground-fault protection, overload protection, and controller sections) → 430.52 sizes the OCPD on a percentage of FLC. 240.4(D)'s caps therefore never apply to a motor branch-circuit OCPD — except where 430.22(G)(1)/(2) explicitly invokes them for the 18 AWG / 16 AWG small-motor conductor exceptions (the "c." conditions: "Overcurrent protection is provided in accordance with 240.4(D)(1)(2)" / "(D)(2)(2)"). That is a deliberate, narrow exception, and it is why those two provisions carry 240.4(D) citations inside Article 430.

What protects the motor conductor at normal running current, then? The overload protection — the thermal element (or electronic equivalent) in the starter, sized on the motor nameplate current per 430.32/430.36 (Class 10/20 elements, 125%/140% of nameplate), which is a SEPARATE device from the branch-circuit OCPD. The two-layer structure is the whole design: the OCPD rides through the starting inrush (it is allowed to be big), and the overload device — which does NOT see the inrush in a correctly coordinated system — protects the conductor at running current. This is why Article 430 requires overload protection separate from short-circuit/ground-fault protection for almost every motor circuit (430.33).

The edition history, verified line by line

Bottom line: the numbers never moved. 125% conductors, 250/175/300/800 OCPD percentages, 72% wye-start, 62.5% part-winding, the 400/225/300/300 increase caps — identical in 2017 and 2023. What moved is structure and naming: the table got a (C)(1) suffix, the next-standard-size exception became main text, the instantaneous-trip provision split into (a)/(b), and Design B gained a "premium efficiency" sibling. A 2017 design note citing "Table 430.52" is still correct in substance in the 2023 code; a 2023 note citing "Table 430.52(C)(1)" points to the same seven rows. 2014 not on disk (no 2014 claim). 2026 renumber flagged on-page where it applies (none of the sections renumbered in the available data).

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

Every number below is produced by the shipped cores in app.js (reqBreakerA(), nextStdBreaker(), pickConductor31016(), smallConductorCap() — node-invoked this session via compute_art38.js) and is asserted in the public test suite (test/run_tests.js in the public repo). The OCPD percentage table (Table 430.52) and the FLC tables (Table 430.248/430.250 rows used) are code — encoded as data (the 430.52 values verified against the on-disk 2017 scan + the on-disk 2023 CSV, word-for-word; the FLC values live-verified this session against two independent clean online transcriptions of Table 430.248 and Table 430.250, because the on-disk 2017 scan of those tables is OCR-garbled in its numeric cells). Table 310.16 values are base values: 30 °C ambient, ≤3 current-carrying conductors. Each example shows the conductor pick in BOTH the 60 °C and 75 °C termination columns — which column governs depends on the termination temperature of the breaker and motor terminal per 110.14(C), and the two answers differ in several of these cases.

EX1 — 3 hp, 230 V, single-phase, continuous duty (the everyday single-phase motor)

A 3 hp, 230 V single-phase motor (a water pump or small compressor). FLC from Table 430.248: 17.0 A.

The conductor is sized at 125% of FLC (21.25 A → 10 AWG Cu on the 60 °C column, 12 AWG Cu on 75 °C), but the inverse-time breaker is at 250% of FLC (42.5 A → 45 A standard). The 45 A breaker exceeds the 10 AWG conductor's 30 A ampacity — legal, because 240.4(G) sends motor conductors to Article 430, and the overload protection in the starter (430.32/430.36, on the nameplate current) is what protects the conductor at running current. Note the 75 °C answer (12 AWG Cu) is only valid if the breaker terminals and motor terminal box are rated for 75 °C terminations at this current (110.14(C)); the 60 °C answer (10 AWG Cu) is the conservative default. The time-delay fuse alternative (30 A) sits at 175% — a different device, a different column.

EX2 — 5 hp, 230 V, three-phase, continuous duty (the everyday 3-phase motor)

A 5 hp, 230 V three-phase motor (a small pump or blower). FLC from Table 430.250: 15.2 A — not the nameplate. This is the three-phase version of EX1.

The three-phase FLA comes from Table 430.250, not 430.248 — the two tables are different (a 5 hp motor is 15.2 A at 230 V three-phase but 28.0 A at 230 V single-phase; the phase count changes the FLC roughly by √3 on the same horsepower). The 40 A breaker on 12 AWG Cu (20 A ampacity) is the same 240.4(G) interaction as EX1. If this were a Design B energy-efficient motor, the only table value that changes is the instantaneous-trip column (1100% instead of 800%) — the inverse-time 250% and the conductor 125% are identical.

EX3 — 2 hp, 230 V, single-phase: the "30 A breaker on 14 AWG" that is code for a motor

A 2 hp, 230 V single-phase motor. FLC from Table 430.248: 12.0 A. This is the example that makes the 240.4(D)/(G) interaction concrete, because the breaker lands far above the small-conductor cap.

A 30 A inverse-time breaker on 14 AWG Cu conductors. On a non-motor circuit that would be a 240.4(D)(3) violation (14 AWG Cu caps at 15 A). On a motor circuit it is exactly what 430.52 prescribes: 250% × 12.0 A = 30 A, a standard size, no rounding. The 14 AWG conductors are correctly sized at 430.22's 125% (15.0 A → 14 AWG at 15 A on the 60 °C column, or 20 A on 75 °C). The starter's overload element (sized on the nameplate, per 430.32/430.36) carries the conductor-protection role. If you sized the nontime-delay fuse instead, 300% × 12.0 = 36 A → 40 A standard — bigger again, and still legal: that is the table working as written, device column by device column.

EX4 — 10 hp, 230 V, three-phase, wye-start delta-run: two conductor sizes, one breaker

A 10 hp, 230 V three-phase wye-start, delta-run motor. FLC from Table 430.250: 28.0 A. Wye-start applies 430.22(C): the line side is at 125% FLC, but the conductors between the controller and the motor are at 72% FLC.

Two conductor sizes on one motor: 8 AWG Cu on the line (125% FLC), 10 AWG Cu from controller to motor (72% FLC). The OCPD is on the line and sizes on the line FLC — 250% × 28.0 = 70 A, a standard size. The 72% is not a rounding convenience: the Informational Note derives it (58% of rated load is what each individual motor circuit conductor of a wye-start motor carries; 58% × 1.25% = 72%), and the line side stays at the full 125% because the line sees the full delta-run current after the start transition.

EX5 — 5 hp, 230 V, single-phase, part-winding: the 62.5% controller side

A 5 hp, 230 V single-phase part-winding motor. FLC from Table 430.248: 28.0 A (yes — a single-phase 5 hp motor has the same table FLC as a three-phase 10 hp motor; phase count, not horsepower alone, sets the FLC). Part-winding applies 430.22(D): line side 125% FLC, controller-to-motor 62.5% FLC.

The part-winding controller-to-motor conductors (12 AWG Cu at 60 °C, 14 AWG Cu at 75 °C) are a full size smaller than the line (8 AWG Cu at 60 °C) — the 62.5% doing its work. Both the 72% (EX4) and 62.5% (EX5) reductions exist because the second winding (part-winding) or the wye-connected starting windings (wye-start) only carry a fraction of the load current, and the 1.25% continuous-duty factor is folded into the multiplier. The OCPD again sits on the line and uses the line FLC: 250% × 28.0 = 70 A.

EX6 — 15 hp, 230 V, three-phase, heavy starting load: the Exception No. 2 increase path

A 15 hp, 230 V three-phase motor driving a heavy start-up load (a loaded conveyor or a pump against head). FLC from Table 430.250: 42.0 A. The base 250% inverse-time breaker (110 A) will nuisance-trip on the start; Exception No. 2 authorizes the increase.

The increase applies ONLY to the OCPD — the conductors stay at 430.22's 125% (52.5 A → 6 AWG Cu), and the overload protection still rides on the nameplate current. The 175 A breaker on 6 AWG Cu looks impossible outside a motor circuit; inside one, it is the Exception No. 2 maximum for an inverse-time breaker with FLC ≤ 100 A. And (C)(2) still applies: if the listed combination controller's overload relay table caps the OCPD below 175 A, the table wins. The split at 100 A FLC matters at the top end: above 100 A FLC, the inverse-time maximum is 300%, not 400% (Exc No. 2(c)).

Gotchas

• Table FLC, not nameplate. 430.6(A)(1): use Table 430.247/430.248/430.249/430.250 values "instead of the actual current rating marked on the motor nameplate" for conductor ampacity and OCPD rating — except low-speed (<1200 RPM), high-torque, and multispeed motors, which use nameplate. The nameplate current is for the OVERLOAD device (430.32/430.36), not the branch-circuit OCPD.
• Single-phase and three-phase have different FLC tables. A 5 hp, 230 V motor is 28.0 A single-phase (Table 430.248) but 15.2 A three-phase (Table 430.250). Pick the table by phase count, not horsepower. (EX2 vs EX5 show the same horsepower landing on different FLCs by phase.)
• The breaker is NOT sized on the wire. 430.22 sizes the conductor (125% FLC); 430.52 sizes the OCPD (250% inverse / 175% time-delay / 300% nontime-delay / 800% instantaneous of FLC). They are different percentages of the same FLC on purpose — the OCPD must ride through the start, the overload device protects the wire at running current.
• 240.4(D) does not cap a motor OCPD. 240.4(G) + Table 240.4(G) send "Motor and motor-control circuit conductors" to Article 430, Parts II, IV, VII. A 30 A breaker on 14 AWG Cu is code for a 12 A-FLC motor (EX3). The only place 240.4(D) re-enters motor sizing is the 430.22(G)(1)/(2) 18/16 AWG small-motor conductor exceptions, which cite it explicitly.
• Rounding: up to the next standard size, never down. 430.52(C)(1) Exception No. 1 (2017; main text in 2023) permits the next HIGHER standard ampere rating when the table product misses a standard size. You never pick the next lower standard size, and you never "round" the conductor — the conductor is the smallest ampacity that meets or exceeds 125% FLC in the correct temperature column.
• The Exception No. 2 increases are maximums, and the controller's table can cap lower. 400/225/300/300% are ceilings, not targets — you go only as far as the starting current requires. And 430.52(C)(2): where the manufacturer's overload relay table shows maximum OCPD ratings, they "shall not be exceeded even if higher values are allowed." In the field, the listed combination controller often binds first.
• Wye-start and part-winding change the CONTROLLER-TO-MOTOR conductors, not the line. Line side stays at 125% FLC in both cases; the controller-to-motor run drops to 72% (wye-start, 430.22(C)) or 62.5% (part-winding, 430.22(D)). The OCPD is on the line and sizes on the line FLC in both. Don't apply the 72/62.5% to the breaker.
• The instantaneous-trip column is not a general breaker. Table 430.52's 800% (Design B: 1100%) column is for instantaneous-trip circuit breakers (MCPs) in listed combination controllers, adjustable, per 430.52(C)(3). A molded-case inverse-time breaker uses the 250% column. Mixing the two columns is a classic error.
• The 2020 body of Article 430 is not on disk. The on-disk 2020 full-code scan ends at Article 230 (its only Article 430 references are cross-references inside Articles 110–230), so the 430.22/430.52 2017→2020 word-diff is not available. The numeric rules are stable 2017–2023; the verified deltas are 2017→2023 (table renamed Table 430.52(C)(1), Exception No. 1 folded into main text, (C)(3) split into (a)/(b), "Design B premium efficiency" added, 430.6's 310.15(B)/(C) → 310.15/310.14(B) renumber). If your jurisdiction adopted 2020, the rule set is the same; the wording is the transitional year.
• The on-disk 2017 FLA tables are OCR-garbled in their numeric cells. The Table 430.250 scan on disk has its column values scrambled (e.g. the 5 hp row prints "230V 17.5" in the scan's layout, which is the 200 V column value bleeding across). Every FLC value in this article's examples was therefore live-verified this session against two independent clean online transcriptions of Table 430.248 and Table 430.250 before use — the values above are the verified ones, and they are what the compute script encodes as data.

The method, step by step

1. Get the FLC from the table. 430.6(A)(1): Table 430.248 (single-phase) or 430.250 (three-phase), by horsepower and rated voltage. Low-speed/high-torque/multispeed → nameplate instead.
2. Size the conductors at 125%. 430.22: 125% of the FLC, pick the smallest conductor in the correct 310.16 temperature column (60 °C or 75 °C per 110.14(C) terminations), applying 310.15 correction factors for ambient/conductor count. Wye-start → controller side at 72% (430.22(C)); part-winding → 62.5% (430.22(D)); other-than-continuous → Table 430.22(E) on the nameplate (430.22(E)).
3. Pick the device, then the percentage. Inverse-time breaker → 250%; time-delay (dual-element) fuse → 175%; nontime-delay fuse (or time-delay Class CC) → 300%; instantaneous trip (listed combination controller, adjustable) → 800% (Design B 1100%) (Table 430.52).
4. Round the OCPD UP to the next standard size (240.6) if the product misses one (430.52(C)(1) Exception No. 1 / 2023 main text). Never round down.
5. If the motor won't start at that size, use Exception No. 2 — increase to 400% (nontime ≤600 A / Class CC), 225% (time-delay), 400%/300% (inverse, split at 100 A FLC), or 300% (601–6000 A class) — only as far as the starting current requires, and never above the controller's overload relay table (430.52(C)(2)).
6. Don't touch 240.4(D) for the OCPD. 240.4(G) sends motor conductors to Article 430; the overload device (430.32/430.36, nameplate-based, in the starter) is the conductor's running-current protection. (240.4(D) only re-enters via 430.22(G)(1)/(2) for 18/16 AWG small-motor conductors.)
7. Quote both, with the edition. "Conductors 12 AWG Cu (430.22, 125% of 15.2 A FLC, Table 430.250, 60 °C column); OCPD 40 A inverse-time (430.52(C)(1), Table 430.52, 250%, next standard per Exception No. 1); overload per 430.32/430.36 on nameplate. 2017/2023 identical." — and note 240.4(G) if the OCPD exceeds the conductor ampacity, because it will.

FAQ

Q: What size conductors for a single motor?
A: 430.22 — 125% of the full-load current, and the FLC comes from Table 430.248 (single-phase) or 430.250 (three-phase) per 430.6(A)(1), not the nameplate. 5 hp, 230 V, 3-ph → 15.2 A FLC → 19.0 A → 12 AWG Cu (60 °C) or 14 AWG Cu (75 °C). Wye-start controller side 72%, part-winding 62.5%, other-than-continuous per Table 430.22(E).

Q: What size breaker for a motor?
A: 430.52 + Table 430.52 — 250% of FLC for an inverse-time breaker, 175% time-delay fuse, 300% nontime-delay fuse, 800% instantaneous trip. 5 hp, 230 V, 3-ph (15.2 A) → 38 A → 40 A standard (next standard up). The device must carry the starting current (430.52(B)); if it can't, Exception No. 2 allows increases up to 400/225/300/300%, and the controller's overload relay table can cap lower ((C)(2)).

Q: Can the breaker be bigger than the wire?
A: Yes — that is the normal case. 240.4(G) + Table 240.4(G) make motor conductors a "specific conductor application" protected per Article 430, so 240.4(D)'s small-conductor caps don't apply. The overload device in the starter (430.32/430.36, on the nameplate current) protects the conductor at running current. A 30 A inverse breaker on 14 AWG Cu (12 A FLC motor) is exactly code (EX3).

Q: What are the 72% and 62.5% conductor values?
A: 430.22(C) wye-start (controller-to-motor conductors at 72% FLC = 58% carried × 1.25) and 430.22(D) part-winding (62.5% = 50% × 1.25). The line side is always 125% in both cases, and the OCPD is on the line sized on the line FLC.

Q: What changed in 2023?
A: The numbers didn't move. 430.22 (A)–(G) is substantively word-identical. 430.52's table is renamed Table 430.52(C)(1) (same values), the next-standard-size exception becomes main text, the instantaneous-trip provision splits into (C)(3)(a)/(b), and "Design B premium efficiency" joins "Design B energy-efficient" at the 1100% instantaneous-trip value. 430.6(A)(1)'s ampacity reference renumbers 310.15(B)/(C) → 310.15/310.14(B). The 2020 body is not on disk (scan ends at Article 230), so no 2017→2020 word-diff is claimed.

Q: Which edition does PanelWright implement?
A: The 2017–2023 rule set for single-motor branch circuits — the numeric rules (125% conductors, 250/175/300/800 OCPD percentages, 72%/62.5% controller-side, the 400/225/300/300% increase caps) are unchanged across both on-disk editions, and the 2023 structural changes are documented on this page. The cores implement Table 310.16 (ampacity), 240.6 (standard sizes), 430.52 (OCPD percentages), and the 240.4(D) small-conductor caps; the FLC tables are encoded as verified data. Verify against the edition adopted in your jurisdiction.

Free, in-browser, no account. The panel schedule's conductor and OCPD picks run the same shipped cores that computed the six examples above.