Free design aid (v1.16). Not a substitute for the NEC, manufacturer instructions, or a qualified electrical design. Built by an AI assistant — see footer.
A real demand-factor load calc for one dwelling unit (≥100 A service). Sums general + appliance + motor loads, applies the 220.82(B) demand (first 10 kVA @100% + 40% of the rest), adds the largest heating/cooling option per 220.82(C), and sizes the service. The appliance/motor nameplate fields accept VA or kW (switch with the “Nameplate units” select — kW is converted at ×1,000, the code calc stays in VA; kVA is considered equivalent to kW). Design aid only — the 220.61 card below handles the neutral load for this method; verify against the adopted NEC edition. Full 220.82 explanation (verbatim code text, the six 220.82(C) options, worked examples) → nec-22082-optional-service-load.html. The service-line conductor it picks comes from Table 310.16 (ampacity table) →. Feeder-side sizing (the 215.2 “larger of (a)/(b)” ampacity rule, the 125% continuous multiplier, the 110.14(C) temperature-column trap, the 55-ampere 215.2(A)(3) service rule, 215.3 OCPD) is explained in the NEC 215.2 feeder ampacity article →; the 215.3 OCPD floor itself (the noncontinuous + 125% × continuous device-rating rule, the 100% listed-assembly exception, the 2020 deletion of Exception No. 2, and the 2023 over-1000 V restructure — feeders to Article 235, OCPD to the new Article 245) is in the NEC 215.1 + 215.3 feeder overcurrent-protection article →. The Termination Temperature Column select on this card is NEC 110.14(C) — 60°C for ≤100 A, 75°C for >100 A, 90°C a derating base only →. The whole pipeline — 240.4 overcurrent (including the 240.4(B) next-standard-size rule and the 240.4(D) small-conductor caps), the 310.15 ambient + conductor-count correction factors, the 240.6(A) standard sizes, and seven core-computed worked examples (the classic 80 A / 6 CCC / 35 °C case → 2 AWG Cu) — is walked through end-to-end in the conductor-sizing article →; the 240.4(D) small-conductor caps themselves (the 14 Cu → 15 A, 12 Cu → 20 A, 10 Cu → 30 A ceiling that overrides Table 310.16, the 18/16 AWG conditional entries, and the (E) tap / (G) motor carve-outs) get a dedicated treatment in the NEC 240.4(D) small-conductors article →. And the disconnecting means that the 220.82 service feeds — where it goes (230.70), how many you may have (230.71's one-disconnect default + the four "two to six" configs and the six-count cap), the grouping rule (230.72), the rating floors (230.79: 15 A one-circuit / 30 A two-circuit / 100 A one-family / 60 A all others), and the combined-rating sum test (230.80) — is in the NEC 230.70–230.80 service-disconnecting-means article →. And the service-entrance conductors (the wires from the meter to the panel) that carry that load — the (A)(1) 125% continuous rule, the (A)(2) "after any adjustment or correction factors" rule, the (B) 230.79-rating floor (why a house's service wire is never below 100 A), the (C) grounded-conductor floor, and the 2020 renumber (310.15 → 310.14 + the new 110.14(C) clause) — is in the NEC 230.42 service-conductor-sizing article →. And the overload protection that polices the match between the service breaker and those service wires — 230.90(A) (OCPD rating or setting not higher than the conductor ampacity, with the five exceptions: motor starts, the 240.4(B)/(C) next-standard-size allowance, two-to-six breakers whose sum may exceed the ampacity where the calculated load does not, fire pumps, and the 83% single-phase dwelling-service rule), 230.90(B) (no breaker in the service neutral), and the 2020 renumber of the 83% rule (310.15(B)(7) → 310.12) — is in the NEC 230.90 service-overload-protection article →
Heating / cooling — enter whichever apply; the largest (220.82(C)) is used automatically
Service-line (ungrounded) conductor — picked from Table 310.16 (230.42(A)(2), 100% of the calculated service current, floored at the 230.79(C) 100 A one-family disconnect rating; 110.14(C) temperature column)
Not the same as 220.54. 220.82 is the single-dwelling optional method. 220.54 is the electric-clothes-dryer rule (5,000 VA min per dryer; Table 220.54 demand applies only when a building has 5+ dryers — a multi-dwelling calc). Don’t conflate them.
The standard-method dryer rule for a service/feeder serving multiple dwelling units. Each electric dryer counts at the larger of 5,000 VA or its nameplate; the demand is the connected load × the Table 220.54 factor for the number of dryers. Design aid only — 220.54 is not the single-dwelling 220.82(B)(3) nameplate treatment, and the 2026 NEC renumbers this (→ 120.54) and revises the factors; verify against the edition adopted in the jurisdiction. Full 220.54 explanation (verbatim code text, the whole Table 220.54, the boundary values, worked examples) →
Where a dwelling unit has four or more appliances rated ¼ hp or greater, or 500 W or greater, fastened in place (not on a cord-and-plug connection) and served by the same feeder or service, 220.53 permits a 75% demand factor on their combined nameplate rating load. The factor does not apply to household electric cooking equipment (use the 220.55 card), clothes dryers (220.54 / 220.82(B)(3)), space-heating equipment, or air-conditioning equipment (220.82(C)) — keep those out of this card’s count. With fewer than 4 eligible appliances the factor is not permitted; the card then counts the load at 100% and flags it. The 2020 code added the ¼ hp / 500 W rating qualifier (2014 had none) — so the 2017–2023 wording is implemented here; the 2023 change analysis records no 220.53 change, and the 2026 NEC renumbers this (→ 120.53 area). Design aid only — verify against the adopted NEC edition. Full 220.53 explanation (verbatim code text, exclusions, worked examples) →
For a service or feeder supplying commercial kitchen equipment, other than dwelling units, 220.56 permits a maximum demand less than the total load where the kitchen is thermostatically controlled or is used on an intermittent basis. Enter the total connected load of the kitchen equipment and the number of units served — the Table 220.56 demand factor applies by count (100%, 100%, 90%, 80%, 70%, 65% at 6 and over). The result must also be at least the sum of the two largest individual loads on that equipment — enter those two and the card checks it automatically, flagging when the two-largest floor governs. This is not the household cooking rule (220.55) — keep household ranges/ovens out of this card. Design aid only — the 2026 NEC renumbers this (Article 120 area); verify against the adopted NEC edition. Full 220.56 explanation (verbatim code text, the whole Table 220.56, the two-largest floor rule, worked examples) →
The standard-method Part III rule for the general-illumination portion of a feeder or service: the Table 220.42 demand factors apply tier-by-tier to the connected lighting load (dwelling units: first 3,000 VA @100%, 3,001–120,000 @35%, remainder @25%). This is not used under the 220.82 optional single-dwelling method — that method takes 3 VA/sq ft at 100% (220.82(B)(1)) with no 220.42 demand. For non-dwelling work, enter the lighting VA from the fixture schedule or your design basis. The factors do not apply when determining the number of lighting branch circuits (220.42). Design aid only — verify against the adopted NEC edition. Full 220.42 explanation (verbatim code text, the whole Table 220.42 by occupancy, the tier-boundary values, worked examples) →
*Table note: the hospital and hotel/motel factors do not apply to areas where the entire lighting is likely to be used at one time (e.g., operating rooms, ballrooms, dining rooms) — size those at 100%.
Maximum demand for household electric ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances individually rated over 1¾ kW (kVA is considered equivalent to kW). Default is Column C (base maximum demand per number of appliances, with the Note 1 5%-per-kW-over-12-kW increase for equal ratings over 12 kW). Note 2 handles unequal ratings (all over 8¾ kW, none over 27 kW); Note 3 is an alternative method for appliances 1¾–8¾ kW using the Column A/B demand factors (in lieu of Column C). For a 3-phase, 4-wire feeder/service, the table count is twice the maximum number connected between any two phases. Design aid only — the 2026 NEC renumbers Article 220 (cooking → 120.55 area); verify against the adopted NEC edition.
Verified: Column C + A/B factors transcribed coordinate-level from the verbatim NFPA 70 2014 Article 220 PDF and cross-checked verbatim against NEC 2020 — the two editions are row-for-row identical (26–40: 15 kW + 1 kW/range; 41+: 25 kW + ¾ kW/range), and the 2023 change analysis records no 220.55 change. Note 4 (single-range branch-circuit loads) is out of scope for this feeder/service calculator. Verify against the adopted NEC edition. Full 220.55 explanation (verbatim code text, the whole table, why the "31+ ranges" web variant is wrong, worked examples) →
The neutral load is the maximum unbalance — the maximum net calculated load between the neutral conductor and any one ungrounded conductor (220.61(A)). Permitted reductions: 220.61(B)(1) 70% applied to the household cooking/dryer portion (only when that load was demand-calculated per Table 220.55 / Table 220.54), and 220.61(B)(2) 70% applied to the portion of the unbalanced load over 200 A (3-wire dc / single-phase ac, 4-wire 3∅, 3- or 5-wire 2∅). For a service or feeder supplying one dwelling unit, the minimum ampacity of the neutral conductor may be 83% of the calculated load (310.12(B)). 220.61(C) prohibited reductions are never applied here: 3-wire portions of 4-wire 3∅ wye circuits and nonlinear loads on 4-wire wye systems stay at 100% (harmonic neutral currents). The tool reports the minimum neutral-conductor ampacity and picks the conductor automatically from Table 310.16 (verified 2023 edition, 30 °C ambient, ≤3 current-carrying conductors) for your chosen material + temperature column — then apply 310.15 adjustments as required. Design aid only — the 2026 NEC renumbers this (Article 120 area); verify against the adopted NEC edition. Full 220.61 explanation (verbatim code text, the two 70% reductions, the 200 A seam, the 310.12(D) neutral-sizing nuance, worked examples) → · The Table 310.16 ampacity table itself (full 28-row table, the 110.14(C) column rule, the 240.4(D) overcurrent caps, boundary values) → · and the service-side bonded neutral side — NEC 250.102(A) (the bonded neutral at the service = the main bonding jumper), Table 250.102(C)(1) (the phase-size-based table with the 12.5% Note 1 and the 200 A / 100 cmil boundary rows), 250.28 (equipment-bonding-jumper size), and six core-computed worked examples — is in the NEC 250.102 main bonding jumper article → · and the separately derived system side — grounding a transformer or generator system: 250.26 (which conductor to ground), the system bonding jumper + grounded conductor + GEC rules (250.30(A)–(C)), the common-GEC tap method for multiple systems (250.30(A)(6)), and Table 250.66 with its electrode-size caps (250.66(A)–(C)) — is in the NEC 250.26 + 250.30 separately derived systems article → · and the what do I bond to earth side — 250.50 (every electrode present gets bonded together), 250.52 (the eight permitted electrodes + the three that are not), 250.53 (the 25-ohm supplemental-rod exception, 6-ft spacing, ring/plate depths, and the 250.53(C) bonding jumper per Table 250.66 — plus why there is no 250.51) — is in the NEC 250.50 + 250.52 + 250.53 grounding electrode system article → · and the how do I actually run it and bond the pipes side — 250.64 (the GEC in one continuous length: no splice except irreversible compression or exothermic welding; Schedule 80 PVC where exposed to damage; the 18-in. aluminum earth rule; the multiple-disconnect tap method + busbar) and 250.104 (water pipe per Table 250.102(C)(1) with the 2020 3/0 Cu / 250 kcmil Al cap; gas pipe per Table 250.122; structural metal per 250.102(C)(1)) — is in the NEC 250.64 + 250.104 GEC installation & piping bonding article → · and the the GEC caps + where it lands on the electrode side — 250.54 (auxiliary electrodes), 250.58 (one common electrode per building), 250.60 (lightning strike-termination devices don't count as electrodes), 250.62 (GEC material), the Table 250.66 electrode caps (6 AWG to a rod, 4 AWG to the Ufer, ring-size to a ground ring — and the rule that voids a cap when the GEC continues on to a table-sized electrode), and 250.68 (the 5-ft water-pipe rule, hold-down bolts, the rebar stub up) — is in the NEC 250.54 + 250.58 + 250.60 + 250.62 + 250.66 + 250.68 auxiliary-electrode / GEC-cap / connection article → · and the what happens when the supply leaves the house side — separate buildings and structures (the detached garage): 250.32(A) (an electrode is required except the single-branch-circuit Exception), (B)(1) (the EGC must run with the supply, and the neutral must not be bonded at the garage), the previous-edition and separately-derived-system exceptions, (D) (the remote disconnect location rules + the 225.32 → 225.31(B) 2023 renumber), (E) (the GEC per Table 250.66 from the largest ungrounded conductor), with six core-computed worked examples — is in the NEC 250.32 separate-building grounding article → · and the when the load is a motor side — a single-motor branch circuit: 430.22 (conductors at 125% of the full-load current, per 430.6(A)(1) from Table 430.248 single-phase / Table 430.250 three-phase — not the nameplate; wye-start delta-run at 72% on the controller side (C), part-winding at 62.5% (D), other-than-continuous duty per Table 430.22(E), and the 14/18/16 AWG small-motor conductor rules (F)/(G)), 430.52 + Table 430.52 (the OCPD: 250% inverse-time / 175% time-delay / 300% nontime-delay / 800% instantaneous of FLC, the next-standard-size step, and the Exception No. 2 starting-current increases to 400/225/300/300% capped by the controller's overload relay table), and the 240.4(D)/(G) interaction (why a 30 A breaker on 14 AWG Cu is legal for a motor) — with six core-computed worked examples in both the 60 °C and 75 °C termination columns — is in the NEC 430.22 + 430.52 single-motor branch-circuit article → · and the how do I set the overload side — the nameplate-current pair to that article: 430.32 (the motor overload device: (A)(1) the separate overload element at 125% of the NAMEPLATE full-load current (115% for standard motors), (A)(2) the thermal protector at 170/156/140% of the TABLE FLC (buckets ≤9 A / 9.1–20 A / >20 A), the 430.32(C) higher-setting cap of 140/130% of nameplate, and the 430.32(D)(2)(a) path where the 430.52 branch OCPD is the overload for a ≤1 hp manually-started motor with the controller in sight), 430.33 (intermittent duty may use the OCPD outright), 430.35(A) (shunting during starting, with the 400% OCPD ceiling), and 430.36/430.37/430.38 (which conductors get the overload — fuses per 430.36, non-fuse units per Table 430.37, and how many conductors the device must open) — with six core-computed worked examples, the verified 2017→2023 deltas (the 2023 "electronically protected" sentence added to (A)(2)/(B)(2); the numbers never moved), and the nameplate-vs-table distinction spelled out — is in the NEC 430.32 + 430.36 motor overload protection article → · and the how do I protect the control circuit side — the third in the motor trilogy: 430.72 (overcurrent protection of the motor control circuit — the tapped-control-circuit rule, Table 430.72(B) Column A separate-protection / Column B branch-OCPD conductors-within-enclosure / Column C conductors-beyond-enclosure, the fire-pump Exception No. 1, the two-wire-transformer-reflected-protection Exception No. 2, and 430.72(C)(1)–(5) control-transformer protection incl. the <50 VA no-protection and <2 A / 500% primary shortcuts) and 430.75 (the disconnecting means — the two-device rule, the immediate-adjacency requirement, the >12-conductor remote exception with qualified-persons access + permanent warning signs, and the transformer-on-the-load-side rule), with 430.71/430.73/430.74 as scope — the "why does my starter's control circuit get a 5-amp fuse" answer, six core-computed worked examples, and the verified 2017→2023 deltas (the numbers never moved; the 725.43→724.43 renumber, the Table 430.72(B)(2) renumber, the 724/725 split) — is in the NEC 430.72 + 430.75 motor control circuit protection article → · and the which device actually starts and stops the motor side — the fourth in the motor series: Part VII Motor Controllers — 430.81 (the two small-motor exceptions: a stationary 1/8 hp motor that runs all the time and can't be damaged by overload makes the branch-circuit disconnect the controller; a portable 1/3 hp motor makes the plug-and-cord the controller), 430.82 (controller design: capable of starting/stopping and interrupting locked-rotor current; autotransformer + rheostat rules), 430.83 (ratings: (A)(1) hp-rated controllers, (A)(2) inverse-time breaker as controller for all motors, (A)(3) molded-case switch, (C) the 2 hp / 300 V switch rules — 2× FLC or 80% ac-only snap switch, (D) torque motors by nameplate current, (E) straight vs slash voltage ratings, and the one real 2017→2023 change: new (F) — the short-circuit-current-rating installation limit), 430.84 (need not open all conductors — unless it's also the disconnect), 430.85 (pole in a permanently grounded conductor), 430.87 (one controller per motor, Exception No. 1 group controllers by equivalent horsepower at ≤1000 V), 430.88/430.89 (weak-field start prohibition + speed limiting), 430.90 (combination fuseholder must fit the Part III overload fuse) — plus 430.8 (SCR marking, 4 exceptions) and 430.9 (terminals, 0.8 N·m torque for 14 AWG and smaller), nine core-computed worked examples, the verified 2017↔2023 delta (430.83(F) is the only structural addition; every number unchanged), the 430.86 mis-citation callout, and the 2017 OCR fraction disclosure — is in the NEC 430.81–430.90 motor controllers article → · and the what actually stops the power side — the disconnecting means for the motor: 430.102 (location: the controller disconnect in sight of the controller, the motor disconnect in sight of the motor AND the driven machinery, and the lockable-110.25 exceptions that let the motor disconnect be omitted), 430.103 (operation: opens ALL ungrounded conductors, no pole independently operable, no auto-close), 430.109 (type: the seven permitted devices + the small-motor relaxations — 1/8 hp → the branch OCPD; ≤ 2 hp / 300 V → 2× FLC general-use switch, 80% ac-only snap switch, or marked manual controller; cord-and-plug → hp-rated plug), 430.110 (rating: 115% of the table full-load current, the combined-load rule with summed locked-rotor currents, and the 2023's new design letter A locked-rotor equation), 430.111 (one breaker as controller + disconnect), 430.112 (group disconnects), 430.113 (multi-source equipment: the 2023 sign-content rule), and the 430.106 gap (the section that does not exist) — with the verified 2017↔2023 delta (two substantive changes: the 430.110(C)(1) design letter A locked-rotor equation and the 430.113 sign content; everything else bookkeeping, all numbers unchanged), eight worked examples, and full table cross-checks — is in the NEC 430.101–430.113 disconnecting means article → · and the where multiple controllers live side by side side — Part VIII Motor Control Centers (430.92–430.99): the single-main-disconnect rule (430.95), the per-controller disconnect exception (430.95(1)), the main-bonding-jumper sizing (250.102(C)(1) via 430.96), the busbar support + phase-arrangement + wire-bending-space rules (430.97(A)–(E) with Table 430.97(D) clearances), the 430.98 marking requirements (nameplate + phase + SCCR + 2023 "current" addition), and the 2017 informational-note → 2023-mandatory short-circuit-rating promotion of 430.99 — with the verified 2017↔2023 delta (430.95 exception numbering, 430.97(C) 312.6(B)→312.6, 430.98(A) "current", 430.99 rewording; all busbar/spacing numbers unchanged), six core-computed worked examples, and the 2017-scan OCR disclosures — is in the NEC 430.92–430.99 motor control centers article → · and the when the motor is fed from a VFD side — Part X Adjustable-Speed Drive Systems: 430.120 (Parts I–IX apply unless modified; 2023 adds the 1000 V / Part XI scope sentence), 430.122 (conductors: (A) 125% of the drive's rated input current — read the drive nameplate, not the motor FLC; 2023 (B) the NEW output-conductor rule at 125% of motor FLC with the "Suitable for Output Motor Conductor Protection" exception; (C) the relocated bypass larger-of rule; (D) several-motors via 430.24), 430.124 (overload: included-in-drive / Part III in the bypass / individual per motor), 430.126 (motor overtemperature: the four means, the thermal-memory exception, the 430.43/430.44 import), 430.128 (disconnect in the incoming line at 115% of the drive's rated input current), 430.130 (branch OCPD: Table 430.52(C)(1) on the motor FLC, the manufacturer-maximum trump card, the 2023 SOOCP exception sizing from the input current), and 430.131 (the drive counts as a motor controller for 430.53 — the smallest-motor branch cap) — with the verified 2017↔2023 deltas (the 430.120 sentence pinned by NFPA SR-7544; the 430.122/430.130 SOOCP restructure pre-dating the 2023 cycle, edition-of-origin gap disclosed; 430.129 does not exist), seven core-computed worked examples (including the sub-15 A 430.53(B) cap answered from the 240.6 list, with the tool's 15 A breaker-core floor disclosed), and the 2017-scan OCR disclosures — is in the NEC 430.120–430.131 adjustable-speed drive systems article → · and the when the motor is over 1000 V (medium voltage) side — Part XI Over 1000 Volts, Nominal — the 2023 renumber of 430.221–430.227 (2017) into 430.201–430.208 (2023), with the full renumber map, the NEW 430.204 wire-bending-space rule (305.5, no 2017 counterpart), the restructured 430.205 (315.60 lead-in + (A) size-from-the-overload-trip-setting, not 125% of FLC + NEW (B) 125% of the drive's rated input current), the 430.206(A) coordinated-protection AS-drive scope (routes MV drives to 430.124/430.126), the 115% relay-trip cap (430.207), and the 2023-expanded 430.208 disconnect (switch/CB + voltage rating ≥ circuit + current rating ≥ 100% of FLC or drive input — 2017 required lockability only) — with the verified 2017↔2023 edition-delta (renumber pinned to the 2023 cycle: the 2020 NEC still used 430.221–430.227 and the NFPA 2021-cycle Second Revisions already target 430.205/430.208; the 2026-cycle SR-8030/8031 430.205/430.208 changes noted out of scope), six core-computed worked examples, and the 2017-scan OCR disclosures — is in the NEC Part XI over 1000 V (430.201–430.208) article → · and the when the feeder itself crosses the 1000-V line side — the Article 215 (Feeders) edition migration: 215.2(B) "Feeders over 600 Volts" (2017) → "Feeders over 1000 Volts" (2020) → relocated to 235.202 (2023, new Article 235 Part III), with the full relocation map (215.2(B)(1)/(2)/(3) → 235.202(A)/(B)/(C) — transformer-nameplate rule, the 125%-of-simultaneous-utilization rule, and the supervised route that gained its 310.14(B)/315.60(B) ampacity anchor in 2020), the ampacity-table renumber 310.15/310.60 → 310.14/315.60 (2020), the 215.1 scope cap "not over 1000 V ac / 1500 V dc" + the 215.2 relettering (215.2(A)(3) → (C) the 55-A rule), and the 215.10 ground-fault-protection ceiling 600 → 1000 V phase-to-phase (2023) — the delta that makes a 1000/577 V wye feeder disconnect require GFPE only under 2023 — with six core-computed worked examples, every delta pinned to the edition it landed in, and the 2020-scan-cutoff + AJB-2020-misquote disclosures — is in the NEC 215.2(B) → 235.202 feeder-relocation article → · and the how does the GEC physically land on the electrode side — the last Article 250 Part III section: 250.70 (Methods of Grounding and Bonding Conductor Connection to Electrodes — exothermic welding, listed lugs, listed pressure connectors, listed clamps, or other listed means; never solder; the ground-clamp listing rules for the electrode + GEC materials and direct soil burial / concrete encasement; the one-conductor-per-clamp limit) plus 250.8 (the general permitted / not-permitted connection means) and 250.10 (physical protection of the clamps), the four-methods hardware list (pipe plug / bolted clamp / communications strap-type clamp / equally-substantial) that the 2023 reorganization removed — folding everything into (A) General + (B) and adding the direct-burial → concrete-encasement Informational Note — with four core-computed worked examples (rod, water pipe, ground ring, Ufer) is in the NEC 250.70 connection-methods-to-electrodes article → · and the when the motor circuit carries a power-factor-correction capacitor side — the capacitor companion to the motor series: 460.9 (the trap: the motor overload is set for the improved power factor, but the motor circuit conductor is not re-sized — the capacitor is disregarded and 430.22 still governs at 125% of the full-load current) and 460.8 (the capacitor's own conductors at 135% of rated current, the one-third rule for the short lead to the motor terminals — never below 135%, the OCPD "as low as practicable," and the disconnecting means rated ≥ 135% that opens all ungrounded conductors and may be used as a regular operating procedure), plus the companion sections 460.6 (discharge of stored energy — 50 V in 1 minute, automatic, never manual), 460.10 (capacitor case to the EGC), and 460.12 (nameplate marking) — with five core-computed worked examples (10 kVAR/480 V and 5 kVAR/460 V stand-alone banks, the 460.9 overload-vs-conductor split on a 5 hp motor, a 2 kVAR/230 V single-phase bank, and the one-third rule where the 135% floor governs) and the verified 2017↔2023 edition story (the Part I PFC core is word-identical; the real deltas are the 460.1 hazardous-locations sentence removal, the 460.2→460.3 renumber with the Article 110 Part II→Part III cross-reference, the 460.24(A) medium-voltage switching reword, and the 490.22→495.22 cross-reference) — is in the NEC 460.9 + 460.8 PFC-capacitor article → · and the when the load is an air-conditioning or refrigerating compressor side — the branch-circuit core of Article 440: 440.22(A) (the branch-circuit short-circuit and ground-fault protective device capped at 175% of the greater of the rated-load or branch-circuit selection current, the 225% starting-current allowance, the 15-ampere floor, and the nameplate marked-maximum trump card) and 440.32 (conductors at 125% of that same greater current, with the 72% wye-start/delta-run rule for the controller-to-motor conductors), plus the companions 440.33 (multi-motor sum + 25% of the largest), 440.52 (the 140% separate overload relay / 125% fuse-or-breaker / 156% thermal protector), and 440.12 (the disconnect at 115%) — with five core-computed worked examples (a clean 175% BCS case, a 3-ton 3-phase split, the 225% starting rung, the 440.33 multi-motor sum, and the 72% wye-delta split) and the verified 2017↔2023 edition story (the numbers never moved; 440.22(A) reorganized into a rule + three Exceptions; the real deltas are 440.8's new bathtub/shower zone, 440.9's non-threaded→compression-type fittings, 440.11's lockable door, 440.14's 110.26(A) working space, and the 440.59→440.55 renumber) — is in the NEC 440.22 + 440.32 air-conditioning branch-circuit article → · and the when the load is a transformer side — the overcurrent-protection core of Article 450: 450.3 + Table 450.3(B) (transformers 1000 V, nominal, or less — 125% primary-only, 250% primary + 125% secondary, the 167% / 300% small-transformer rows, and the Note 3 six-times / four-times coordinated-overload allowance), Table 450.3(A) (the over-1000-V grid — 600 / 400 / 300% primary keyed on rated impedance and supervised location), 450.4(A) (autotransformers — 125% / 167% of the rated full-load input current, never the shunt winding), and 450.6 (secondary ties — the 67% / 100% / 133% ampacity rules, the 250% + reverse-current relay pair, and the 150-V-to-ground switch rule), with six core-computed worked examples (a 100 kVA 480/208 at every row of Table 450.3(B) including the Note 3 six-times ceiling, a 25 kVA 24 V lighting transformer, the 50 kVA autotransformer 125% case + the sub-9 A 167% corner, a two-75 kVA secondary tie with the 225 A 450.6(B) OCPD, and a 5 MVA 13,800/480 MV transformer on the Table 450.3(A) grid) and the verified 2017↔2023 edition story (the OCPD numbers never moved — 39 machine-verified checks; the real deltas are 450.1's exception→list rework with the article references removed and 450.10's "Bonding" title, both Mike Holt-documented, plus the 240.100/240.101→245.26/245.27 and 250.24(B)→250.24(C) and 314.16(B)→314.16(B)(1) cross-reference renumbers, the 450.9 IEEE re-cites + no-storage marking, and 450.14's "lockable open") — is in the NEC 450.3 transformer overcurrent article → · and the how the transformer physically gets installed side — the installation core of Article 450 Part I: 450.8 (guarding — mechanical protection, the noncombustible moisture-resistant case, 110.27/110.34 guarding of energized parts, and the voltage warning signs), 450.9 (ventilation — dispose of the full-load heat losses, unblocked openings, marked clearances), 450.10 (grounding — the terminal bar bonded in the enclosure per 250.12, the 250.8 wire-lead Exception, other metal parts per 250 Parts V–VII), 450.11 (the eight required nameplate items), 450.12 (terminal wiring space — 312.6 bending space + the Table 314.16(B)(1) pigtail volumes), 450.13 (accessibility — the 50 kVA hollow-space boundary), and 450.14 (disconnecting means — in sight or remote, "lockable open" in 2023, field marking, Class 2/3 exempt), with four core-computed worked examples (a 15 kVA 480/208 terminal-wiring-space + box-fill pick, the 50 kVA hollow-space boundary crossing, the Class 2/3 exemption test, and the eight nameplate items) and the verified 2017↔2023 edition story (the installation rules are substance-identical — 52 machine-verified checks; the real deltas are 450.9's IEEE re-cites + no-storage marking, 450.10's "Bonding" title + (B) conditional drop, the 450.12 314.16(B)→314.16(B)(1) renumber, and 450.14's "lockable open") — is in the NEC 450.8–450.14 transformer installation article → · and the where may it physically live, by insulation type side — Part II “Specific Provisions Applicable to Different Types of Transformers”: 450.21 (dry-type indoors — the 112½ kVA transformer-room boundary: ≤ 112½ kVA gets 300 mm (12 in.) separation or a heat-insulated barrier (Exception: fully enclosed ≤ 1000 V nominal needs neither); over 112½ kVA needs a 1-hour fire-resistant transformer room unless Class 155 insulation (barrier or 6 ft H / 12 ft V separation, or fully enclosed); over 35,000 V goes to a Part III vault), 450.22 (dry-type outdoors — weatherproof enclosure + no 12 in. of building combustible material over 112½ kVA unless Class 155 + enclosed), 450.23 (less-flammable liquid — listed liquid with a 300 °C fire point; the 35,000 V indoor cap: Type I/II + no storage + liquid confinement + listing restrictions, or auto fire-extinguishing + confinement, or per 450.26), 450.24 (nonflammable fluid — indoors or outdoors; vault over 35,000 V; confinement area + pressure-relief vent + gas absorption or chimney/flue; the nonflammable definition: no flash point, no fire point, not flammable in air), 450.25 (askarel — 25 kVA pressure-relief-vent boundary, poorly-ventilated gas path, 35,000 V vault), 450.26 (oil-insulated indoors — Part III vault + all six Exceptions: 112½ kVA 4-in reinforced-concrete vault, no-vault 10 kVA combustible / 75 kVA fire-resistant at ≤ 1000 V, furnace 75 kVA, charged-particle-accelerating 75 kVA / 1000 V, detached qualified-persons building, surface-mining equipment with the 6-mm (1/4-in.) steel barrier), 450.27 (oil-insulated outdoors — the four fire safeguards: space separation, fire-resistant barrier, automatic fire suppression, oil-confining enclosure with trapped drains), 450.28 (modification — the fluid-change marking rule) — with five core-computed worked examples (the 112½ kVA boundary crossing, the no-vault 10/75 kVA boundaries, the 25 kVA askarel vent boundary, the 35,000 V indoor cap at 5 MVA, and the surface-mining exception) and the verified 2017↔2023 edition story (every boundary number unchanged — 192 machine-verified checks, no Mike Holt 2023 entries for Part II so all deltas on-disk-verified: the 450.21(B) 1-hour-rating fuse-in + Exception-fragment explicitation + E119-15→E119-18a, the 450.23 may→can / If-clause / NFPA 220-2015→2021 rework, and the 450.27 C2-2007→C2-2017 re-cite) — is in the NEC 450.21–450.28 transformer-types Part II article → · and the what the vault itself must be built of side — Part III “Transformer Vaults”: 450.41 (location — ventilate to the outside air without flues or ducts, wherever practicable), 450.42 (walls + roofs 3-hour fire resistance, earth-contact floors 100 mm / 4 in. concrete, 3-hour floors over vacant space/stories, studs and wallboard prohibited, the 1-hour Exception with automatic sprinkler / water spray / CO2 / halon protection, typical 3-hour = 150 mm / 6 in. reinforced concrete), 450.43 doorways (the 3-hour tight-fitting door + AHJ exterior requirement, the 100 mm / 4 in. oil-confining sill, locks + qualified persons only; 2023’s one substantive Part III change: personnel doors capable of opening not less than 90 degrees in the direction of egress + listed fire exit hardware), 450.45 ventilation (the 450.9 hook: the 1900 mm² (3 in.²) per kVA net-opening rate, the 0.1 m² (1 ft²) floor under 50 kVA — exact break-even 52.63 kVA, computed — the roughly-half-near-the-floor arrangement or all-in-the-roof, durable coverings, 1-1/2-hour automatic closing fire dampers on indoor openings, fire-resistant ducts), 450.46 (the more-than-100 kVA drain + floor pitch), 450.47 (no foreign piping — fire-protection and transformer-cooling piping excepted), 450.48 (nothing stored) — with five core-computed worked examples (the per-kVA ventilation rate + floor, the 100 kVA drain boundary, the 75 kVA vault door package, the 450.45(B) split, and the 3-hour / 1-hour / 1-1/2-hour rating ladder) and the verified 2017↔2023 edition story (one substantive change — 450.43(C)’s egress sentence — plus three Informational Note re-cites: E119-15→E119-20, NFPA 80-2013→80-2019, ANSI/UL 555-2011→555-2020; 119 machine-verified checks, no Mike Holt 2023 entries for Part III so all deltas on-disk-verified; there is no 450.44) — is in the NEC 450.41–450.48 transformer-vaults Part III article → · and the where the EGC connects and stays continuous side — the EGC's last two stops before a device: 250.130 (EGC connections — the (A)/(B) service-equipment bonding split for grounded vs ungrounded systems, and the six permitted connection points for existing-installation receptacle/switch replacement and branch-circuit extensions; 2023 adds snap switches + the 404.9(B) note) and 250.148 (continuity and attachment of EGCs to boxes — the 2023 "connected together" rule, device-removal continuity, the metal-box dedicated connection now sized from Table 250.122 on the largest OCPD in the box, the nonmetallic-box arrangement, and the deleted (E) solder rule that 250.8(B) now carries) — with five core-computed worked examples and the verified 2017→2023 edition story (80 machine-verified checks; no Mike Holt 2023 entry for 250.130, so all its deltas on-disk-verified) — is in the NEC 250.130 + 250.148 EGC-connections & box-continuity article → · and the how do I size the wire and breaker for an appliance side — the Article 422 Part II branch-circuit core: 422.10 (branch-circuit rating — the 125%-of-marked-rating continuous-load floor with the 100%-listed-device escape, the Table 220.55 range route, and the two-or-more-loads hand-off to 210.23) + 422.11 (overcurrent protection — the 150%-of-marked ceiling, the 20 A cap on unmarked appliances ≤ 13.3 A, the 48 A heater subdivision with the mains-count-as-branch-circuits rule, and the motor/hermetic hand-offs) + 422.12 (central heating on its own circuit) + 422.13 (the storage water heater as a 125% continuous load), with five core-computed worked examples (the 4,500 W water heater's 25 A / 10 AWG pick and the 240.4(D) 12 AWG rejection) and the verified 2017→2023 edition story (52 machine-verified checks; eight deltas including the 422.13 125% rewrite and the 210.19(A)(3)→(C) range cross-ref renumber) — is in the NEC 422.10 + 422.11 + 422.12 + 422.13 appliance branch-circuit article → · and the when one branch circuit carries several motors side — the multi-motor companion to the single-motor article: 430.24 (the conductor sum — 125% of the highest-rated motor's table FLC + 100% of the other motors + 100%/125% of the non-motor loads, with the 430.22(E) short-time-duty exception, the 424.3(B)/424.4(B) space-heating hand-off, and the interlock rule) + 430.53 (the OCPD routes — (A) several ≤ 1 hp motors on 120 V at ≤ 20 A, (B) the OCPD capped by the smallest motor's 430.52 value, (C) the full group route with the Table 430.52 OCPD sum + the 430.40 smallest-overload cap, and (D) the single-motor taps incl. the 1/10-of-the-OCPD tap to a "Suitable for Tap Conductor Protection" controller) — with five core-computed worked examples (the 5+2+1 hp group landing on an 80 A OCPD over 6 AWG Cu — legal by the 240.4(G) motor-circuit exemption — the smallest-motor 30 A cap, the 14 AWG / 20 A small-motor circuit, and both tap routes) and the verified 2017→2023 edition story (no number moved; the 424.3(B)→424.4(B) renumber, the 430.53(B) conditions-list rework, the 430.53(C)(1)–(5) restructure with the 430.40 cap merged into (C)(4), the (D) tap consolidation, the Table 430.52 → 430.52(C)(1) ref renumber, and the Design B "premium efficiency" prose rename — the 1100% row was already in the 2017 table) — is in the NEC 430.24 + 430.53 several-motors-one-branch-circuit article → · and the when the appliance hangs off a cord (or a fan hangs off the ceiling) side — the Article 422 Part II installation core: 422.16 (flexible cords — the (A) general permission with the 2023 NEW (A)(3) heater-cord rule relocated from the deleted 422.43, and the (B) specific-appliance conditions: in-sink disposers at 450 mm–900 mm, dishwashers at 0.9 m–2.0 m / compactors at 0.9 m–1.2 m with the 2023 opening-bushing clause, wall ovens, and range hoods at 450 mm–1.2 m on an individual branch circuit — now including over-the-range microwaves with integral hoods in 2023), 422.18 + 314.27(C)/(E) (paddle-fan support — the 32 kg (70 lb) sole-support cap, the 16 kg (35 lb) marking floor, and the 2023 rename of the "locking support and mounting receptacle" to a weight-supporting ceiling receptacle (WSCR) + weight-supporting attachment fitting (WSAF), plus the 2023 NEW 422.18(B) bathtub/shower zone of 900 mm × 2.5 m), and 422.22 (the "other installation methods" catch-all that 2023 rewrites into a WSCR appliance-mounting path) — with the 2017→2023 deletion of 422.15 (central vacuum) and 422.43 (heater cords) documented, five core-computed worked examples (the 5 A disposer's 240.4(D) boundary, the 4,500 W dishwasher's 14 AWG rejection, the 800 W range hood, the 70 lb fan-cap table, and the tub/shower-zone distance checks), and 55 machine-verified edition checks — is in the NEC 422.16 + 422.18 + 422.22 appliance flexible cords & ceiling-fan-support article → · and the how does the appliance get disconnected, and how must it be built and marked side — the Article 422 Part III/IV/V core: 422.30 (the appliance disconnecting-means lead) + 422.31 (the disconnecting means — the branch-circuit OCPD route, the unit-switch route with the 2023 NEW routing lead, and 422.31(C) the >1/8 hp / motor-operated hand-off to 430.109/430.110), 422.33 (receptacle disconnecting means — the 422.33(B) range-drawer accessibility rule (the Mike Holt-documented 2023 "shall be permitted" rewrite) and the 422.33(C) receptacle-rating floor), 422.34 (unit switches — the marked-off-position lead + (A)–(D) the snap-switch / 2× FLC / 300 V / door-switch routes), 422.35 (the marked nameplate rating), 422.40–422.50 (Part IV construction — the 422.42 appliance-identification marking, the 422.44/422.45 grounding rules, the 422.46 temperature-limiting means [deleted in 2023], the 422.47 limit-means rule (with the 60 kW Ex 1 and the 2023 ANSI Z21.22 note drop), the 422.48 (A)/(B) lampholder rules (the 300 W boundary), and the 422.50 listing requirement [deleted in 2023]), and 422.60–422.62 (Part V marking — the nameplate rating + the motor-loads marking rules) — with the 2017→2023 deletion of 422.46 and 422.50 documented, five core-computed worked examples (the 50 A range on a 40 A receptacle rejection, the 422.33(B) range-drawer 45 A floor, the 300 VA / 115 V unit-switch boundary, the 422.31(C) + 430.110(C)(1) disconnect rating (4.0 + 1.09 = 5.09 A → 15 A), and the 422.47/422.48 limit-means + lamp-boundary package), and 75 machine-verified edition checks — is in the NEC 422.30–422.62 appliance disconnecting means, construction & marking article → · and the what size circuit, conductors, and disconnect for my baseboard / duct / radiant heater side — the Article 424 Parts I–IV core: 424.4 (the branch-circuit rules — the 2023 125% continuous-load conductor rule, the 30 A two-or-more-outlets cap, and the non-dwelling 50 A infrared allowance) + 424.10–424.13 (installation — the baseboard-receptacle rule, the deleted 2017 "special permission" clause, supply-conductor marking, damp/wet locations, combustible spacing) + 424.19–424.22 (control & protection — the disconnecting means at 125% of the load, in-sight-or-lockable-open, unit switches, thermostatically controlled switching, indicating switches, and the 48 A heating-element subdivision) + 424.28–424.29 (the nameplate and field-replaceable element rating) — with the verified 2017→2023 edition story (thirteen deltas: the 424.3→424.4 renumber + the continuous-load→125% conductor reword (the one Mike Holt-documented change), the 424.2→424.3 renumber with the NEW Table 424.3, the 424.9→424.10 renumber + 210.50(B)→210.52, the 424.10 "Special Permission" deletion, the 424.11 insulation-rating reword, the 424.12(B) water-sentence drop, the 424.19 lockable-open reword, the 424.19(C) general-purpose-circuits reword, the 424.20(A) new accessible-location condition, the 424.22(A) cross-ref reword, the 424.22(B) 424.3(B)→424.4(B), and the 424.28(B) "easily" drop — no number moved) — five core-computed worked examples (the 12,000 W / 240 V heater's 62.5 A / 6 AWG Cu / 70 A package, the 30 A cap on two heaters with the 240.4(D) 12 AWG → 20 A trap, the 62.5 A heater's 48 A element subdivision, the 25 A breaker-as-disconnect, and the 50 A non-dwelling infrared ride) — is in the NEC 424.1–424.29 fixed electric space-heating article → · and the what size circuit, conductors, OCPD, and disconnect for my industrial process heater side — the Article 425 Parts I–IV core: 425.3 (2017) / 425.4 (2023) (the branch-circuit rules — individual circuits at any rating, the continuous-load declaration), 425.8–425.14 (installation — the 425.10 renumber, the deleted 425.9/425.10, supply-conductor marking, damp/wet, combustible spacing, the 425.14 infrared-lamp rule), 425.19–425.22 (control & protection — the disconnecting means at 125% of the load, in-sight-or-lockable-open, unit switches, the 48 A heating-element subdivision with the 120 A / 150 A allowance (2020), and the 50 kW marked-minimum-conductor route), 425.28–425.29 (the nameplate and field-replaceable element rating) — with the verified 2017→2023 edition story (twelve deltas: the 425.1 scope reword + exclusion drop, the 425.2→Table 425.3 renumber, the 425.3→425.4 renumber + (A) reword, the 425.8→425.10 renumber, the 425.9 + 425.10 "Special Permission" deletions, the 425.14 comma cleanup, the 425.19 lockable-open reword, the 425.19(A)(2)(2) unit-switch rework, the 425.22(A) cross-ref reword, the 425.22(B) 120 A / 150 A allowance + 425.3(B)→425.4(B), the 425.22(C) list rework, and the 425.28 marking reword — no Mike Holt 2023 entries, so all on-disk-verified) — five core-computed worked examples (the 15,000 W / 240 V heater's 78.75 A / 4 AWG Cu / 80 A package, the 25 A breaker-as-disconnect on a motor-less immersion heater, the 41.67 A heater under the 48 A element threshold, the 120,000 W / 480 V heater's 50 kW 100%-vs-125% conductor route, and the 120 V infrared-lamp section) — is in the NEC 425.1–425.29 fixed resistance & electrode industrial process-heating article →. The NEC 690.1–690.15 solar photovoltaic (PV) systems article → is the "what voltage ceiling, what wire, what OCPD, and what rapid-shutdown / disconnect for my solar array?" article — the 600 V dwelling / 1000 V other / 1500 V off-building maximum-voltage ceilings and the Table 690.7(A) cold-weather Voc correction, the 690.8/690.9 125% current + OCPD sizing, the 690.11 80 V dc arc-fault rule, the 690.12 rapid-shutdown limits (30 V / 80 V / 8 ft), and the 690.13 / 690.15 disconnecting-means + isolating-device rules — verbatim 2017 + the on-disk Mike Holt 2023 change summary (4 in-scope changes: 690.4, 690.7, 690.12, 690.15), 120 machine-verified checks, · and the when the equipment is over 1000 V (medium voltage) and the article itself moved side — the edition migration of the medium-voltage article: 2017 Article 490 “Equipment Over 1000 Volts, Nominal” → 2023 Article 495 “Equipment Over 1000 Volts ac, 1500 Volts dc, Nominal” — 38 verbatim 2017 sections (five parts, disclosed OCR fixes), the full section map (Part I 490.1–3 → 495.1–3, Part II 490.21–25 → 495.22–25 with 490.21 → NEW Article 245 (245.21), Part III 490.30–48 → 495.30–49 with the NEW 495.49 reconditioned-switchgear section, Part IV 490.51–56 → 495.61–66, Part V 490.70–74 → 495.70–74), the 490.36+37 → 495.37 merge (+ 250.190), the NEW 495.2 reconditioned-equipment ban, eleven substantive text deltas (incl. the 495.72(D) 7% → 7½% ground-fault threshold and the 495.35(B) “either → both” control-equipment rule), and the Table 490.24 → 495.24 clearance grid (values verified digit-identical 2017→2023) — 132 machine-verified checks, core-computed worked examples, is in the NEC 490 → 495 equipment over 1000 V article → · and the what protects the circuit itself when it crosses the 1000-V line side — the brand-new 2023 Article 245 “Overcurrent Protection for Systems Over 1000 Volts ac, 1500 Volts dc, Nominal”: the 2017 rules at 240.100 + 240.101 (Article 240 Part IX) and 490.21 (Article 490 Part II) consolidated into one medium-voltage overcurrent article — 245.1 scope, 245.2 reconditioned-equipment OCPDs (NEW), 245.21 circuit-interrupting devices (from 490.21 — the 2017→2023 text diff letter-by-letter), 245.26 feeders & branch circuits (from 240.100), and 245.27 OCPD ratings & settings (from 240.101 — the 3× / 6× setting caps unchanged) — 44 on-disk 2023 rows + the 2017 source, every delta machine-verified, plus three core-computed worked examples — is in the NEC 245 overcurrent protection over 1000 V article →. And the how do I ground the neutral, the equipment, and the fence when the system itself is over 1000 V side — Article 250 Part X in full, 250.180–250.194 verbatim from BOTH the on-disk 2017 NFPA scan and the on-disk 2023 dataset: 250.184 solidly grounded neutrals (the 600 V neutral-insulation floor, the 33⅓% neutral-ampacity floor with the 20% engineering-supervised Exception, and the 400 m / 1300 ft multigrounding-electrode spacing with the NEW 2023 Exception for the jacket-removal-only case), 250.186 service-supplied AC grounding (Table 250.102(C) floor, the 1/0 AWG parallel floor, the 3-wire-delta full-ampacity rule, the 310.10(H)→(G) re-cite), 250.187 impedance grounding (qualified persons + ground detectors + no line-to-neutral loads, the 57.7% max neutral voltage, the 2023 "impedance grounding conductor" reword + NEW bare-conductor Exception), 250.188 portable/mobile equipment (impedance-grounded supply, the 100 V frame-to-ground cap, 6.0 m / 20 ft electrode isolation, the 490.55 → 495.65 renumber), 250.190 equipment grounding (the 6 AWG Cu / 4 AWG Al floors — copper-clad aluminum added in 2023 — and Table 250.122 on the OCPD rating), and 250.191/250.194 substation grounding (IEEE 80, the 5 m / 16 ft fence trigger, 50 m / 160 ft jumper intervals, the 2.5 m / 8 ft guy-wire bond) — ten machine-diffed 2017→2023 deltas (no number moved), six core-computed worked examples — is in the NEC 250.180–250.194 over-1000 V grounding (Article 250 Part X) article →. And the where do the over-1000-V branch-circuit, feeder, and service rules live when the article itself is brand-new side — the 2023 NEC Article 235 “Circuits Over 1000 V, Nominal”, the full consolidation of 2017’s over-1000-V rules (210/215/225/230 Part VIII) into one medium-voltage article — 40 top-level sections (91 on-disk rows), the two-step edition story (600→1000 V in 2020; article created in 2023), ten machine-diffed deltas, six core-computed worked examples — is in the NEC Article 235 circuits-over-1000-V (branch circuits, feeders, services) article →. · and the how must a switchboard / switchgear / panelboard be rated, protected, and marked side — NEC Article 408 (408.1–408.58) verbatim from both the on-disk 2017 NFPA scan (27 sections) and the on-disk 2023 dataset (all 60 rows), the 408.3/408.4 panelboard-rating rules (the 600 A busbar / 800 A enclosure cap), 408.36–408.38 overcurrent protection, 408.41–408.47 short-circuit-current rating, and the 2023-new 408.43 face-up/face-down ban — seventeen machine-diffed 2017→2023 deltas (one number moved: 408.2) plus six core-computed worked examples — is in the NEC 408 switchboards, switchgear & panelboards article → · and the what device, what rating, what place side — NEC Article 406 (406.1–406.13) verbatim from both the on-disk 2017 NFPA scan (12 sections) and the on-disk 2023 dataset (all 67 rows): the 406.3(B) 15 A / 125 V rating floor, the 2023-new 406.3(D) termination rules (the 15 A / 14 AWG push-in corner), the 406.4(D) replacement rules (GFCI listed + GFPE + the 210.12(C) AFCI extension), the 406.12 tamper-resistant expansion (7 → 10 locations), the 406.9 wet-location rework (90-degree hinged covers, the 900 mm × 2.5 m bathtub/shower zone), the 406.6(D) 1 W night-light/USB faceplate limit, and the 2023-new 406.13 single-pole separable-connector section — 21 machine-diffed 2017→2023 deltas plus six core-computed worked examples — is in the NEC 406 receptacles, attachment plugs & flanged inlets article → · and the what switch, what rating, what place side — NEC Article 404 (404.1–404.30) verbatim from both the on-disk 2017 NFPA scan (19 sections) and the on-disk 2023 dataset (all 47 rows): the 404.2(C) grounded-conductor rule (5 electronic switches per branch, 25 per feeder), the 404.8(B) 300 V adjacent-device limit, the 404.14 rating/switch-form rework (LED/ballast loads + the 2023-new 404.14(D) 15 A push-in / 14 AWG termination corner), the 2023-new 404.16 reconditioned-switch section, and the 2023-new 404.30 closed-door interior-access restriction — 29 machine-diffed 2017→2023 deltas plus six core-computed worked examples — is in the NEC 404 switches article → · and the what is the ampacity of a flexible cord, and what changed in 2023 side — NEC Article 400 (400.1–400.52) flexible cords & flexible cables verbatim from both the on-disk 2017 NFPA scan (25 top-level sections) and the on-disk 2023 dataset (all 56 rows, 38 top-level sections, Parts I–IV): the Table 400.5(A)(1) ampacity grid (byte-identical 18→2 AWG, 0 of 17 rows differ), the 400.5 re-cite to the 2023 Article-310 tables (310.15(B)(2)(a)→310.15(B)(1)(1); 310.15(C)→310.14(B)), the UL 817/62 note relocated 400.1→400.12 (+ the 590.4 attachment-surface cite), 400.17 “reduced→adjusted”, 400.35 “or latches”, and the brand-new 2023 Part IV (400.40–400.52) portable power feeder cables over 2000 volts — 10 machine-diffed 2017→2023 deltas plus six core-computed worked examples — is in the NEC 400 flexible cords article → · and the what lighting is allowed where, and what changed in 2023 side — NEC Article 410 (410.1–410.197) luminaires, lampholders & lamps verbatim from both the on-disk 2017 NFPA scan (68 top-level sections, Parts I–XV) and the on-disk 2023 dataset (all 164 rows, 83 top-level sections, Parts I–XVII): the brand-new 2023 Part XVI horticultural lighting (410.170–410.186, incl. the 410.184 GFCI/SPGFCI rule) and Part XVII germicidal irradiation (410.191–410.197, the UV-safeguard system), the 9-section renumbering (410.48→50, 410.50→51, 410.74→80, 410.103→100, 410.118→120, 410.120→122, 410.121→124, 410.122→126, 410.151→150), the drop of 410.46 (folded into the rewritten 410.42/410.44), the 410.2 reconditioned-luminaire ban, the 410.10(D) ceiling-fan light-kit extension, the 410.16 180→150 mm recessed clearance fix, the 410.82 handlamps deletion, the 410.130(G)→410.71 disconnecting-means relocation (now covering LED), the 410.151→410.150 220.43→220.46 re-cite, the 410.141 “lockable open” change, and the 410.136/410.137 test-reference updates — 32 machine-diffed 2017→2023 deltas plus six core-computed worked examples — is in the NEC 410 luminaires article → · and the what is fixture wire, and what changed in 2023 side — NEC Article 402 (402.1–402.14) fixture wires verbatim from both the on-disk 2017 NFPA scan (11 top-level sections, disclosed scan artifacts: the Table 402.3 grid interleaved across a page break with OCR XFE*/150°G/(392°) artifacts flagged-not-asserted) and the on-disk 2023 dataset (all 12 rows = 10 top-level + 2 sub-rows): the Table 402.5 ampacity grid (byte-identical 18→10 AWG — 6/8/17/23/28 A, 0 of 5 rows differ), Table 402.3 (31 on-disk fixture-wire types, 60 °C TF/TFF to 250 °C PAF/PTF), 4 machine-diffed 2017→2023 deltas — 402.2 “see Article 410” → “See Part VI of Article 410”, 402.5 “allowable” drop, 402.5 310.15(A)(3)→310.14(A)(3) re-cite, and the substantive one: 240.5(B)(2) now permits “15- or 20-ampere circuits” on the 18 AWG (50 ft) / 16 AWG (100 ft) tap rows (2017 said “20-ampere circuits” only) — plus the machine-verified finding that Article 403 is a numbering gap in both editions — is in the NEC 402 fixture wires article →
Checks the voltage drop of a single circuit run against the code’s informational-note guidance: ≤ 3% at the farthest outlet of power, heating, and lighting loads (210.19(A) Info Note No. 3, branch circuits) and ≤ 5% maximum total on feeders + branch circuits combined (215.2(A)(1) Info Note No. 2 — NEC 2020 text; both are recommendations, not mandatory limits). Uses DC resistance at 75 °C from NEC Chapter 9, Table 8 (cross-checked against three independent 2023-edition sources + the 2023-based codeelec print on disk; K-factor ≈ 12.9 Cu / 21.2 Al for 8 AWG–4/0). Formula: Vd = C × I × R with C = 2 (single-phase, one round trip) or √3 (three-phase line-to-line), R = ohms/kft × one-way feet ÷ 1,000. For 3∅ 4-wire use the line-to-line voltage (e.g. 208 / 480). The picked conductor is NOT checked against ampacity (Table 310.16) — use the other cards for that; this card only sizes for drop. Design aid only — verify against the adopted NEC edition. Full voltage-drop explanation (the 3/5 rule, Vd = C·I·R, K-factor, verbatim 2020 code text, worked examples) → · the 3% feeder-side note lives in 215.2(A)(1) (feeder ampacity article) → · the branch-circuit side (the Article 100 "Continuous Load" definition, 210.19(A)(1)(a) 125% rule, 210.20(A), the 80% reciprocal, and this 3%/5% note in full context) is in the NEC 210.19(A) continuous-load article →
Applies the two mandatory Table 310.16 adjustments that the other cards leave to you: 310.15(B)(1) ambient-temperature correction (multiplier from the 16-row table, 30 °C base) and 310.15(C)(1)(a) adjustment for more than three current-carrying conductors (4–6 → 80%, 7–9 → 70%, 10–20 → 50%, 21–30 → 45%, 31–40 → 40%, 41+ → 35%). The factors multiply (310.15(A) Note): base ampacity × ambient factor × CCC factor, applied to the conductor's ampacity in the same insulation-temperature column you select (the 60 °C column is only available down to 51–55 °C ambient; the 75 °C column stops at 71–75 °C — the code prints no factor beyond that, and the tool says so instead of guessing). 240.4(D) small-conductor OCPD caps (14/12/10 Cu, 12/10 Al) are applied as the governing ampacity where the cap is lower than the derated value. Count the current-carrying conductors only — the equipment grounding conductor and a neutral carrying just the unbalanced current of a multi-phase system do not count (310.15(C)(2)). Enter a size in the last box to check a specific conductor, or leave it empty to auto-pick the smallest size that survives. Factors coordinate-verified from a verbatim 2023-NEC print + live cross-checks (Session 38). 110.14(C) termination ratings still apply — verify the device rating. Design aid only. Full 310.15 explanation (verbatim code text, both factor tables, the counting rules, the multiply rule, the 240.4(D) cap interaction, the 2017→2020 renumber trap, worked examples) → · Full conductor-sizing explanation (worked 310.15 examples, the 60/75/90 °C rule, 240.4(D) caps) → · this card implements 210.19(A)(1)(b) — the branch-circuit rule that the derated ampacity must still cover the load (the 125% continuous-load article) →
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210.11(C) is a dwelling-unit count rule, not a load rule: in addition to the circuits sized by the Article 220 load, a dwelling unit needs 2× small-appliance (210.52(B)), 1× laundry (210.52(F)), 1× bathroom (210.52(D)) and, with an electric garage, 1× garage (210.52(G)(1)) — all 20 A, 120 V. The bathroom circuit may have no other outlets (single-bathroom exception per 210.23(A)); the garage circuit may also serve readily accessible outdoor receptacles — and 210.11 has no outdoor or lighting-circuit mandate (210.11(B) is load proportioning only). Each required small-appliance/laundry circuit is also a 1,500 VA feeder line (220.52 / 220.82(B)(2)). 2017–2023 code verified (no 2023 change); 2026 renumber flagged. Full 210.11 explanation (verbatim code text, the four mandatory circuits, the two exclusivity gotchas, the 220.52/220.82 VA tie-in, worked examples) → · and the load-permission side — what each of those circuits may actually supply (the 80% cord-and-plug cap, the 50% fixed-equipment cap, 30/40/50 A occupancy limits, the 2023 10-ampere addition, and the full Table 210.24 summary) — is in the NEC 210.23 + 210.24 permissible-loads article → · and the where do the outlets go side — the 6-foot wall-space rule, the 24-inch countertop rule, the small-appliance circuit mandates, and the 2023 island/peninsula change — is in the NEC 210.52 dwelling-unit receptacle-outlets article → · and the how those wires carry their ID side — white/gray grounded conductors (200.6), green EGCs (250.119), clearly-distinguishable hots (310.110(C)), the multi-voltage phase/line labeling, the DC polarity rule, and the orange high leg (110.15) — is in the NEC 210.5 branch-circuit identification article → · and the what rating does each receptacle get side — the 210.21 outlet-device rules, the Table 210.21(B)(2) 80% max-load table (12/16/24 A), the Table 210.21(B)(3) receptacle ratings ("15 or 20" on a 20 A circuit), the (B)(1) dedicated-circuit minimum, and the (B)(4) range-receptacle allowance — is in the NEC 210.21 outlet-devices / receptacle-rating article → · and the how to size, identify, and mark the equipment ground side — why the EGC is green (or green with yellow stripes), the three 250.119 exceptions, the 4 AWG-and-larger identification rule (strip / color green / green tape, must encircle), Table 250.122 minimum EGC sizes by OCPD rating, the 250.122(B) proportional-increase rule, and the 310.120 required markings with their 24-in / 40-in repeat intervals (310.120 → 310.8 in the 2020 renumber) — is in the NEC 250.119 + 310.120 EGC-identification & marking article → · and the how to size the equipment ground itself side — Table 250.122 minimum EGC sizes by OCPD rating (15 A → 4000 A, Cu and Al), the 250.122(A) never-larger-than-the-circuit ceiling, the 250.122(B) proportional-increase rule (and the "new in 2020?" edition trap), (C) multiple circuits, (D) motor circuits, (E) flexible cord, (F) parallel conductors, (G) feeder taps, with eight core-computed worked examples — is in the NEC 250.122 equipment-grounding-conductor sizing article → · and the which of those circuits need arc-fault protection side — 210.12 (the dwelling-unit room scope, the six permitted AFCI means, the 50 ft / 70 ft distance limits, the 6 ft extension-exemption test, the 2020 patient-sleeping-room scope expansion, and the 2023 restructure to (A)–(E) with 10-ampere circuits) — is in the NEC 210.12 AFCI-protection article → · and the which of those receptacles need ground-fault protection side — 210.8 (the dwelling-unit location list, the non-dwelling location list, the 6 ft sink/tub distance tests, the 2017→2020 restructure — 125 V only → 125-through-250 V receptacles, whole basements, damp indoor locations, new (D) specific appliances, new (E) the 210.63 HVAC service receptacle, new (F) all outdoor outlets — plus the TIA 1653 listed-HVAC exception) — is in the NEC 210.8 GFCI-protection article → · and the how big is the breaker that protects each of those circuits side — 210.20 (the (A) 125%-of-continuous-load FLOOR on the overcurrent-device rating, with the listed-assembly 100% Exception; the (B) hand-off to 240.4 for the conductors; the (C) Table 240.3 equipment cap; the (D) 210.21 outlet-device cap; the 2017→2020 word-identical delta and the 2023 posture where the 10-ampere allowance is a 210.18 change, not a 210.20 change) — is in the NEC 210.20 branch-circuit overcurrent-protection article → · and the what rating is that circuit side — 210.18 (the OCPD sets the circuit rating, not the wire; the closed list of multioutlet ratings 15/20/30/40/50 A, with 10 A added in 2023 and barred from supplying receptacles by the new Exception No. 2; the >50 A multioutlet industrial-exception broadened in 2023 from "on industrial premises" to "in locations"; why 25 A is a legal breaker but not a legal multioutlet circuit rating; the 2017→2020 word-identical delta and the four verified 2023 changes) — is in the NEC 210.18 branch-circuit-ratings article → · and the where the breaker and fuse sizes come from side — 240.6 (the official catalog of standard ampere ratings: Table 240.6(A) 15–6000 A for fuses and inverse-time breakers, the 2023 addition of 10 A, the fuse-only 1/3/6/10/601 A list, (B) the adjustable-trip maximum-setting rule, (C) restricted access = the adjusted setting with the 2020 password method, and the brand-new 2023 (D) for remotely adjustable breakers and their cybersecurity conditions) — is in the NEC 240.6 standard-ampere-ratings article →
| Pos | Circuit | Type | Load (A) | Cont. | Rec. breaker | Actual | Notes | |
|---|---|---|---|---|---|---|---|---|
The 5% neutral badge is a screening guideline — not a NEC limit. No NEC edition sets a percent-unbalance requirement on panelboards: the badge compares the panel’s neutral estimate (worst-phase deviation) against 5% of the panel rating as a quick proportionality screen. The real neutral-sizing authority is NEC 220.61 (maximum unbalance + 70% reductions + 310.12(D) 83% one-dwelling floor). Phase arrangement and the high-leg “Caution” marking are NEC 408.3(E)/(F) (2014–2023: “Support and Arrangement of Busbars and Conductors”), with the orange high-leg marking at 110.15. Full 408.3 explanation (the 408.3(C) edition trap, the 5%-screen truth, worked examples) → nec-4083-busbars-phase-identification.html