PanelWright / NEC 210.23 + 210.24 permissible loads

NEC 210.23 + 210.24 — what may a branch circuit actually supply?

The permissible-loads rules for multiple-outlet branch circuits (2014–2023 editions, 2023 changes flagged), the full Table 210.24 summary, and seven worked examples — every number computed by the shipped calculator core.

Why this matters

Table 310.16 tells you how much current a wire can carry; 240.4/240.6 tells you how to protect it. But 210.23 answers a different question: what kind of loads may live on a circuit of a given size at all? You can have perfectly sized wire and a correctly rated breaker and still be out of code if the circuit is supplying something its subsection forbids — a 15 A circuit wired with 14 AWG copper and a 15 A breaker is fine as a circuit, but it may not carry a fastened-in-place appliance rated above 50 percent of its rating, and no single plug-in device above 80 percent.

This is the rule electricians hit on every panel schedule: the 20 A branch circuit that can legally carry a 2,400 W load only if the load is the right kind. Article 14 of this series covers sizing the wire for a given current (210.19(A) + the 125% continuous-load rule); this article covers the load-permission layer underneath it.

210.23 — the rule in verbatim text (NEC 2020)

Four loads to keep straight:

• Any one cord-and-plug device (not fastened in place) ≤ 80% of the circuit rating — 210.23(A)(1), repeated in 210.23(B) for 30 A. The 80% is the reciprocal of the 125% continuous-load factor: a single plug-in device is assumed to be able to run at full output continuously, so it is capped at 100% ÷ 1.25 = 80%.
• Total fastened-in-place equipment (other than luminaires) ≤ 50% of the rating — 210.23(A)(2), but only when lighting and/or cord-and-plug equipment shares the circuit.
• 30/40/50 A circuits carry occupancy restrictions — fixed lighting with heavy-duty lampholders only outside dwellings (30 A), cooking appliances in any occupancy (40/50 A), and nothing over 50 A may feed lighting at all.
• The 210.11(C) dwelling circuits are walled off — the required small-appliance, laundry, and bathroom circuits supply only the receptacle outlets 210.11(C) specifies.

The 2023 change: 10-ampere branch circuits

The 2023 NEC (via 210.18) permits 10 A branch circuits, and 210.23 grew a new subsection for them (quoted from the ELR 2023 code-language preview, fetched 2026-08-31; the “N” marks are the 2023 new-language flags):

Two consequences worth noting: (1) a 10 A circuit has no receptacle outlets at all — it is a lighting/fan circuit, so the 80% cord-and-plug rule has almost no surface to apply to; (2) 2023 also split Table 210.24 into Table 210.24(1) (copper) and Table 210.24(2) (aluminum and copper-clad aluminum), which is why 2023-era documents cite “Table 210.24(1)” for the copper rows. This article works from the 2014–2023 single Table 210.24 (copper column shown, aluminum noted) and flags the 2023 deltas.

Table 210.24 — the summary (2014–2023, copper column)

¹ Copper (2023: Table 210.24(1); aluminum and copper-clad aluminum in Table 210.24(2)). ² For receptacle rating of cord-connected electric-discharge luminaires, see 410.62(C). (Footnotes per the 2020 text; “Lampholders permitted” row OCR normalized from “Lampholdcrs pennittcd”.)

Three readings that are easy to get wrong:

• The table gives minimum wire, not maximum load. “Circuit wires 12” on a 20 A row means 12 AWG Cu is the smallest permitted — not that the circuit may only carry what 12 AWG carries. Load permission comes from the 210.23 subsections above; sizing comes from 210.19/210.20/210.21 (the conductor-sizing article covers the full pipeline).
• Receptacle rating ≠ circuit load limit. A 20 A circuit accepts 15 or 20 A receptacles — but the load per single receptacle is still capped by Table 210.21(B)(2) (16 A on a 20 A circuit), as covered below.
• The 240.4(D) caps sit on top. Even though the table says 14 AWG for a 15 A circuit, the OCPD on 14 AWG is capped at 15 A, on 12 AWG at 20 A, on 10 AWG at 30 A (Cu) — the same caps the shipped core enforces via smallConductorCap().

The receptacle-side twin: Table 210.21(B)(2)

Read together with 210.23(A)(1): on a multi-outlet 20 A circuit, one receptacle may carry 16 A of cord-and-plug load, but a duplex (two or more receptacles) may be loaded to the full 20 A circuit rating. The 80% applies to a single receptacle’s share, not to the circuit as a whole when the load is spread across multiple receptacles.

Worked examples (every number from the shipped core)

All seven examples are computed by the real core functions (pickConductor31016, smallConductorCap, nextStdBreaker, round2) under node this session (income-lab/compute_art15.js → calc_21023_cited.json) and asserted in the public test suite — the article’s numbers can never drift from the tool.

EX1 — the 80% cap on a 20 A circuit (210.23(A)(1))

A 20 A branch circuit (12 AWG Cu, 20 A OCPD per Table 210.24). One cord-and-plug device, not fastened in place, at 120 V:

The 2,400 W heater is the classic exam trap: it is exactly the circuit’s ampere rating, so “in no case shall the load exceed the branch-circuit ampere rating” is satisfied — but a single plug-in device may not exceed 80 percent. On a 15 A circuit the cap is 12 A (Table 210.21(B)(2)); on a 30 A circuit it is 24 A.

EX2 — the 50% fixed-equipment cap (210.23(A)(2))

The same 20 A circuit also supplies lighting. Total utilization equipment fastened in place (other than luminaires):

Note the asymmetry: plug-in equipment gets 80%, fixed equipment gets 50% — and only when lighting or plug-in equipment shares the circuit. A dedicated circuit with nothing else on it is not subject to (A)(2). Luminaires are excluded from the 50% count entirely.

EX3 — Table 210.24 conductor picks (2014–2023, copper)

The shipped Table 310.16 core (60 °C column per 110.14(C) for ≤100 A circuits) reproduces the table’s minimums exactly:

Two subtleties the core surfaces: (1) at the 75 °C column the pick for a 20 A requirement would be 14 AWG Cu (20 A @75 °C) — but the table still requires 12 AWG for a 20 A circuit, because 210.24 states minimum circuit wire, and the 14 AWG row’s 20 A value sits in the 75 °C column whose use is governed by 110.14(C) and 240.4(D) (the 15 A cap on 14 AWG is why a 20 A OCPD can never ride on it); (2) the 240.4(D) caps are computed by smallConductorCap(): 14 Cu→15, 12 Cu→20, 10 Cu→30, 12 Al→15, 10 Al→25.

EX4 — the 2023 10-ampere circuit (210.23(A), new)

A 2023 10 A lighting circuit: core pick for 10 A in the 60 °C column → 14 AWG Cu (15 A) — the smallest table size carries it. The OCPD story is where it gets interesting: the shipped nextStdBreaker(10) returns 15 A, because 10 A is not a standard ampere rating in 240.6(A) — yet the 2023 Table 210.24(1) lists a 10 A OCPD row. In practice a 10 A circuit is protected per the 2023 table (10 A OCPD on 14 AWG); the standard-size machinery of 240.4(B) applies to the next-step-up picks, and 10 A OCPDs exist as a listed device class for this purpose. If your adopted edition predates 2023, 10 A branch circuits are not permitted at all (210.18).

EX5 — duplex vs single receptacle on a 20 A circuit (the 210.21(B)(2) nuance)

The print’s own phrasing: “the key word is ‘receptacle,’ which means one.” One receptacle = 80%; the rest of the circuit (other receptacles, fixed loads) can bring it up to the full rating.

EX6 — the 240.4(D) small-conductor caps (the caps that protect Table 210.24)

These are exactly the caps the shipped core returns from smallConductorCap() (verified in EX3) and the reason the Table 210.24 OCPD column (15/20/30 A on 14/12/10 Cu) is not “the wire’s ampacity” but a protected value. See the 210.19(A) article for the 16 A continuous / 20 A circuit case where the cap forces 12 AWG.

EX7 — the 80% cap on a 30 A circuit (210.23(B))

A 30 A circuit (10 AWG Cu, 30 A OCPD, heavy-duty lampholders) in a non-dwelling occupancy, supplying one cord-and-plug device at 120 V:

The 30 A rule also forbids fixed lighting with ordinary lampholders in a dwelling — heavy-duty lampholders only, and only outside dwellings. A 30 A “lighting” circuit in a house is an exam red flag.

Where 210.23/210.24 fit in the whole pipeline

• Before sizing: 210.23 decides whether the load may ride the circuit at all (this article).
• Sizing the wire: 210.19(A) — ampacity ≥ noncontinuous + 125% of continuous, with the (A)(1)(b) derated floor and (A)(2) rating floor (article 14).
• Protecting it: 210.20(A) — OCPD ≥ noncontinuous + 125% of continuous, then 240.4(B) next-standard-size and 240.4(D) caps (article 13).
• What the device may draw: Table 210.21(B)(2) — per-receptacle cord-and-plug limits (this article, EX1/EX5).
• Dwelling minimums: 210.11(C) — the required small-appliance/laundry/bathroom circuits that (A)’s exception walls off (article 10).

The PanelWright tool checks the sizing/protection half (the panel card, the conductor-derating card, the voltage-drop card). The load-permission half — which subsection a circuit’s load falls under — is a judgment the schedule author makes; this article is the reference for that judgment.

Editions

• 2014 / 2017 / 2020: identical 210.23 structure — (A) 15/20 A with (A)(1) 80% and (A)(2) 50% + the 210.11(C) exception, (B) 30 A, (C) 40/50 A, (D) >50 A; single Table 210.24. (Title + structure verified: 2020 full-code text on disk; up.codes index shows the same title in 2014/2017/2020; the 2023 PDH change analysis on disk carries no 210.23/210.24 change other than the 2023 items below.)
• 2023: 10 A branch circuits permitted (210.18) → new 210.23(A) 10-ampere subsection with the permitted/not-permitted lists; 15/20 A text renumbered to (B); Table 210.24 split into (1) copper / (2) aluminum + copper-clad aluminum. (ELR 2023 change summaries fetched 2026-08-31.)
• 2026: renumbering into the new Article 120 area reported by secondary CE sources — flagged, not implemented here; the tool and this article document the 2014–2023 rule set.

Panel schedules, 220.82 service loads, 220.61 neutrals, 310.15 derating, voltage drop — free, in-browser, data stays local. Design aid, not an engineering seal.

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