NEC 210.21 Outlet Devices — the receptacle-rating rules: why a 15 A receptacle on a 20 A circuit is fine, the 80% max-load table (12/16/24 A), and the 240.4(D) caps those receptacles sit on

The full 210.21 section verbatim — (A) lampholders, (B)(1) the single-receptacle minimum, (B)(2) the maximum cord-and-plug-connected load (Table 210.21(B)(2)), (B)(3) receptacle ratings by circuit size (Table 210.21(B)(3)), and (B)(4) the range-receptacle demand allowance — plus the 240.4(D) small-conductor OCPD caps that the receptacle ratings sit on top of, and seven worked examples where every number is computed by the shipped calculator core. Last updated 2026-09-01 (written for PanelWright v1.16).

Runs in your browser. No account, no install, data never leaves your machine. The panel card sizes every branch circuit against its load and checks the 210.11(C) dwelling-circuit mandates (the very receptacle circuits this article's ratings apply to), the Conductor derating card applies the 310.15 corrections and the 240.4(D) small-conductor caps as the governing ampacity, and the 220.82 card sizes the optional dwelling service — the exact pipeline this article explains.

The rule in one sentence

Outlet devices — receptacles and lampholders — shall have an ampere rating not less than the load to be served and shall comply with 210.21(A) (lampholders) and 210.21(B) (receptacles). For receptacles, that means: a single receptacle on an individual (dedicated) circuit must be rated not less than the branch circuit (210.21(B)(1)); a receptacle on a multi-outlet circuit may not supply a total cord-and-plug load above the 80% cap in Table 210.21(B)(2) (15 A → 12 A, 20 A → 16 A, 30 A → 24 A) and must carry one of the Table 210.21(B)(3) ratings (15 A circuit → 15 A; 20 A → 15 or 20 A; 30 A → 30 A; 40 A → 40 or 50 A; 50 A → 50 A); and a range receptacle may be rated by its single-range 220.55 demand load (210.21(B)(4)). This is the rating of the device — not where it goes (210.50 / 210.52) and not the wire size (240.4(D) + Table 310.16), though the 240.4(D) caps on 14/12/10 AWG are the reason a 20 A receptacle on a dedicated circuit is fed by 12 AWG, not 14 AWG.

The code text (verbatim, with edition notes)

210.21 — Outlet Devices (lead-in, verbatim)

"Outlet devices" is the code's umbrella term for the devices that plug into or mount on a branch circuit — receptacles and lampholders. The lead-in is the governing sentence: the device rating shall not be less than the load to be served, with (A) and (B) spelling out the specifics. Everything below hangs off that one sentence.

210.21(A) — Lampholders (verbatim)

(A) is the short branch: a lampholder on a circuit rated over 20 A must be heavy-duty, and a heavy-duty lampholder must be rated at least 660 W (admedium) or 750 W (any other type). Most of this article is about (B) — receptacles — because that is where the 20 A circuit / 15 A receptacle / 80% max-load questions live.

210.21(B) — Receptacles (verbatim, (1) through (4))

Four subsections, four jobs. (B)(1) is the dedicated-circuit rule — the receptacle must match or exceed the circuit. (B)(2) is the per-receptacle 80% max-load cap. (B)(3) is the receptacle-rating schedule by circuit size. (B)(4) is the range allowance. The two tables below are the numeric heart of (B)(2) and (B)(3).

Table 210.21(B)(2) — Maximum Cord-and-Plug-Connected Load (verbatim)

The "80% rule" everyone quotes is this table. Each maximum load is exactly 80% of the receptacle rating — the reciprocal of the 125% continuous-load multiplier (1 / 0.8 = 1.25) that appears in 210.20(A) and 210.19(A)(1)(a). It is a per-receptacle cap on cord-and-plug-connected equipment, and it applies only where the circuit supplies two or more receptacles or outlets (the multi-outlet case in (B)(2)); a single receptacle on a dedicated circuit is governed by (B)(1), not by this table.

Table 210.21(B)(3) — Receptacle Ratings for Various Size Circuits (verbatim)

The row that answers "can I put a 15 A receptacle on a 20 A circuit?" is the 20 A row: "15 or 20." Both are conforming. The 15 A circuit row is "Not over 15" — the NEC lists a 15 A receptacle for a 15 A circuit. Note the asymmetry that trips people up: a 20 A receptacle is allowed on a 20 A circuit, but the NEC does not list a 20 A receptacle for a 15 A circuit. That is the "15 or 20 on a 20-amp circuit" rule in the title — and its inverse, which is the field-identification reason the 20 A receptacle has a slanted neutral slot.

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

Every number below is produced by the shipped cores in app.js (pickConductor31016(), smallConductorCap(), nextStdBreaker(), cookingDemand22055()) running under node this session — see income-lab/compute_art19.js → calc_21021_cited.json — and is asserted in the public test suite (test/run_tests.js in the public repo). The two 210.21 tables are code text (quoted verbatim above); the determinations and the conductor/OCPD picks are computed from that text + the shipped cores, not hand-asserted. Unless a row says otherwise, conductor picks are in the 75 °C column (110.14(C) terminations) at 30 °C ambient with ≤3 current-carrying conductors.

EX1 — the 80% max-load table, with computed watt equivalents

Computed from the verbatim Table 210.21(B)(2) by the shipped core: each maximum load is exactly 80% of the receptacle rating, and the watt equivalents are max-load × voltage. The 1,920 W / 16 A row is the one that bites in practice — a 20 A wall receptacle on a multi-outlet circuit may not have more than 1,920 W of cord-and-plug-connected equipment plugged into it (at 120 V), regardless of how many 20 A circuits feed the outlet box.

EX2 — the (B)(3) receptacle-rating determinations (the 15-on-20 case + the conforming set)

Determined by the shipped core from the verbatim Table 210.21(B)(3) (minimum-rating reading: a receptacle at or above the listed minimum is conforming). The two conforming rows on a 20 A circuit — 15 A and 20 A — are the whole point of the "15 or 20" row. The single nonconforming row (20 A receptacle on a 30 A circuit) is the mirror-image mistake: a 30 A circuit cannot take a 20 A receptacle. Flagged ambiguity (not asserted in the table): a 20 A receptacle on a 15 A circuit. The listed-schedule reading ("Not over 15") lists a 15 A receptacle only; the minimum-floor reading (device rating not less than the load) says a 20 A device on a 15 A circuit is fine. The NEC prints the cell as "Not over 15" and the article quotes it as listed without resolving the reading — check the adopted edition's commentary.

EX3 — (B)(1) the single-receptacle minimum: a dedicated 20 A circuit

(B)(1) is the one place the receptacle must match the circuit: a single receptacle on an individual 20 A circuit needs a 20 A receptacle. And the 20 A receptacle cannot be fed by 14 AWG copper — the 240.4(D)(3) cap (15 A) is below the 20 A the circuit requires, so the wire must be 12 AWG Cu (25 A ampacity, 20 A cap). This is the (B)(1) + 240.4(D) interplay: the receptacle rating (20 A) and the wire size (12 AWG, not 14 AWG) are two separate rules that both must hold, and the 240.4(D) cap is what forces the wire up one size. The 240.4(D) small-conductor article works the cap in full.

EX4 — the 240.4(D) trap the (B)(1) picks sit on

The receptacle-rating rules in (B)(1)/(B)(3) assume the circuit they rate is a legal circuit. The 240.4(D) caps are what make a circuit legal in the first place for small conductors: 14 AWG copper has 20 A of ampacity but its OCPD is capped at 15 A, so it cannot feed a 20 A receptacle's circuit; 12 AWG copper (25 A ampacity, 20 A cap) can. 12 AWG aluminum (20 A ampacity) is capped at 15 A — one size down from copper — which is why an aluminum 20 A circuit must go to 10 AWG aluminum (25 A cap). All three picks above are computed by the shipped pickConductor31016() + smallConductorCap() cores.

EX5 — a 30 A receptacle on a 30 A circuit (the 24 A max-load row)

A 30 A circuit takes a 30 A receptacle (the (B)(3) row is exactly "30"), and that receptacle may not supply more than 24 A (2,880 W at 120 V) of cord-and-plug-connected load — the (B)(2) 80% row. The conductor is 10 AWG Cu: 35 A ampacity in the 75 °C column, capped at 30 A by 240.4(D)(7), so the 30 A OCPD is legal. The receptacle (30 A), the breaker (30 A), and the wire (10 AWG, 30 A cap) all agree.

EX6 — (B)(4) the range receptacle: rated by the 220.55 single-range demand

(B)(4) is the allowance that lets a range receptacle be rated by its single-range 220.55 demand load rather than by a fixed circuit-rating value. A 12 kW range's 220.55 Column C single-range demand is 8 kW (8,000 VA) = 33.33 A at 240 V — well below a 50 A circuit rating. So a 50 A range receptacle on a 50 A circuit (8 AWG Cu, 50 A) is more than adequate for the 33.33 A demand; the (B)(4) allowance is what permits rating the receptacle by the demand rather than requiring the receptacle to equal the full 50 A circuit rating. The 220.55 cooking-demand article works the full Table 220.55 and the single-range branch-circuit loads (Note 4).

EX7 — a 40 A circuit: the "40 or 50" row

A 40 A circuit takes a 40 A or 50 A receptacle (the (B)(3) row is "40 or 50"). The conductor is 8 AWG Cu in either the 75 °C column (50 A ampacity) or the 60 °C column (40 A ampacity) — 8 AWG is the smallest 75 °C copper size with ≥ 40 A of ampacity, and the 60 °C column (≤100 A circuits per 110.14(C)(1)(a)) lands 8 AWG at exactly 40 A. No 240.4(D) cap applies to 8 AWG (it is larger than the (D) small-conductor sizes), so the 40 A OCPD is legal on 8 AWG Cu. The "40 or 50" row is the same pattern as the "15 or 20" row — two listed receptacle ratings for one circuit size.

Editions: 2014 / 2017 / 2020 / 2023

• Title & structure (all four editions): the section title "Outlet Devices" (210.21) and the internal (A)/(B)(1)–(4) structure are identical in the 2014, 2017, 2020, and 2023 NECs. Verified this session: the up.codes section index names "210.21 Outlet Devices" identically across all four editions (fetched 2026-09-01), and the official 2017 NFPA text on disk shows the (A)/(B) layout quoted above.
• 2017 = 2020 word-identical: a programmatic word-level diff of the 2017 official 210.21 text against the on-disk 2020 full-code text this session found the body word-identical — the only remaining token differences are OCR artifacts in the 2020 scan (line-break hyphens, a "nore:" for "note:", etc.), not code changes. Both tables (B)(2) and (B)(3) are cell-identical.
• No 2023 change to 210.21: the 2023 PDH change analysis records no 2023 change to 210.21 (the 2023 change in Article 210 was the Table 210.24 split into Table 210.24(1) copper / Table 210.24(2) aluminum for the new 10 A circuits — a 210.24 change, not a 210.21 change). The 2023-NEC-based study print on disk (codeelec_2023.txt) quotes Table 210.21(B)(2) with the same 12/16/24 A values and the 80% framing, and a 2023-edition online text of 210.21 (electricalcode.net, fetched this session) matches the 2017 text quoted above. The values are edition-stable across 2014–2023.
• 2026 out of scope, flagged: the 2026 NEC renumbers Article 210 (toward the 120 area) — the 210.21 receptacle-rating rules are expected to move with the article, but the 2026 text is outside this article's edition scope (2014–2023). Cite by the 210.21 values (12/16/24 A max loads; 15/20/30/40-or-50/50 receptacle ratings) and they are stable across the editions covered here.

Free panel schedule & service-load tools

The panel card sizes every branch circuit against its load, checks the 210.11(C) dwelling-circuit mandates (the small-appliance, laundry, bathroom, and garage receptacle circuits this article's ratings apply to), and flags continuous loads. The Conductor derating card applies the 310.15(B)(1) + 310.15(C)(1) corrections and the 240.4(D) small-conductor caps as the governing ampacity (the exact EX3/EX4 pipeline). The 220.82 card sizes the optional dwelling service and its conductors (Table 310.16, 110.14(C) columns), and the 220.55 card computes the single-range demand that (B)(4) lets a range receptacle be rated by (the exact EX6 pipeline). Breaker picks use the NEC 240.6(A) standard-size list. All results print in the rollup CSV export and the branded PDF project report.

Sources & verification