Toolchest · Datasheet

Wire & Ampacity — Dataset Notes

Accumath Toolchest dataset #14. One CSV (accumath-wire-ampacity.csv), two sections distinguished by the section column:

• conductor — 55 rows: AWG 40 through 4/0 (44 sizes) and 250–1000 kcmil (11 sizes). Conductor geometry, DC resistance, and bare-copper weight.
• ampacity — 21 rows: AWG 14 through 4/0 and 250–750 kcmil. Allowable ampacities for copper and aluminum at 60 °C, 75 °C, and 90 °C conductor temperature ratings.

Every value is a published number transcribed from the open manufacturer literature named in each row's source column. No values were computed, interpolated, or estimated. Where no consulted source publishes a value, the cell is blank (see Gaps).

Ampacity section — basis and rules

• Basis (as the source charts state it): ampacities are for 30 °C ambient, not more than three current-carrying conductors in a raceway, cable, or earth. Temperature-correction and conductor-count adjustment factors are not included in this dataset.
• The numbers are the NEC Table 310.16 allowable ampacities as republished in Southwire's openly published ampacity charts and cable specification sheets (including SPEC 45001 and SPEC 10005, and Southwire's Alumaflex / aluminum XHHW-2 literature for the aluminum columns). The NEC/NFPA document itself was not used as a source. Southwire's own footnote (SPEC 10005) states: "Ampacities based upon 2023 NEC Table 310.16 and do not take into account the overcurrent protection limitations in NEC 240.4(D)."
• NEC 240.4(D) small-conductor overcurrent caps — a rule, not part of the numbers: regardless of the table ampacity, overcurrent protection for small conductors is capped at 15 A for 14 AWG, 20 A for 12 AWG, and 30 A for 10 AWG copper. These caps are recorded here only; they are not folded into the ampacity values in the CSV.
• Table 310.16 begins at 14 AWG, so there are no ampacity rows below 14 AWG. Aluminum entries in the table begin at 12 AWG, so the 14 AWG aluminum cells are blank.
• Edition note: the 300 kcmil aluminum values (195/230/260 A) and the 700 kcmil aluminum 60 °C value (315 A) follow current (2020/2023-cycle) manufacturer republications. Some older manufacturer tables print 190/230/255 A for 300 kcmil aluminum and 310 A for 700 kcmil aluminum at 60 °C.
• Final installations must follow the National Electrical Code as adopted and amended locally. This dataset is reference data, not a design substitute.

Conductor section — basis

• Resistance is DC resistance at 20 °C, nominal, for annealed (soft) copper, in ohms per 1000 ft.
• AWG diameters are the solid nominal diameters that define the AWG size. Stranded conductors have a larger overall diameter than the solid equivalent. Where Southwire SPEC 45001 publishes a compact-strand conductor diameter (1/0 AWG–1000 kcmil), it is recorded in the row's row_notes. For kcmil sizes the main diameter is the stranded conductor diameter from Service Wire's bare-copper table, with the alternate stranding noted per row.
• kcmil resistance values are Service Wire's soft (annealed) bare column at 20 °C. The same sheet publishes higher resistances for medium-hard and hard-drawn tempers; those are not building-wire values and are not included.
• Southwire's cable spec sheets publish DC resistance at 25 °C, a different basis; those values were not used in the 20 °C column.
• Weight is bare copper only, lb per 1000 ft. For 1/0 AWG and larger it is the stranded-conductor weight as published (Southwire SPEC 45001; Service Wire), which includes the stranding lay allowance. For AWG 1–11 it is the solid nominal weight from Essex's magnet-wire engineering data; for 12 and 14 AWG, Encore Wire's bare-copper data sheet.

Sources

• Southwire — ampacity charts and cable specification sheets (SPEC 45001 copper XHHW-2, SPEC 10005, Alumaflex and aluminum XHHW-2 literature): all ampacity values; compact-strand conductor diameters and conductor weights for large sizes.
• Service Wire Co. — Bare Copper, Stranded Conductor data sheet (250–1000 kcmil; ASTM B-1/B-2/B-3/B-8): stranded diameters, soft-copper DC resistance at 20 °C, and weights for kcmil sizes.
• Nearson — Copper Magnet Wire Data (per NEMA MW1000 / ASTM B3): nominal resistance at 20 °C used at 30 and 40 AWG (see Discrepancies).
• Essex (EIS) — Magnet Wire Engineering Chart and engineering data: solid bare-copper nominal weights, AWG 1–11; AWG↔mm conversion values corroborate the chart diameters. Essex also publishes the resistance constants (copper: Ω/1000 ft @ 20 °C = 10371 / circular-mil area; aluminum 1350: = 16782 / circular-mil area at 61.8 % IACS) — cited here for reference only; no dataset values were computed from them.
• Encore Wire — bare copper data sheet: weights for 12 and 14 AWG.
• Standard AWG conductor size table (the long-published AWG chart republished in industry literature): AWG diameters (in and mm), circular-mil areas, mm² areas, and nominal resistance at 20 °C for AWG sizes.
• CodePass AWG/kcmil conversion table: mm² areas for kcmil sizes.

Discrepancies found between published sources

• 40 AWG resistance: the AWG chart prints 1049 Ω/1000 ft; the Nearson NEMA MW1000 manufacturer table prints 1079 Ω/1000 ft, which is used here.
• 30 AWG resistance: the AWG chart prints 103.2 Ω/1000 ft; Nearson prints 103.7 Ω/1000 ft, which is used here. All other AWG resistances agree with the Essex/Nearson manufacturer tables within last-digit rounding.
• Southwire SPEC 45001's finished-cable and conductor data are for compact strand; its diameters are smaller than concentric-lay Class B strandings of the same size (Service Wire). Both are published; each is labeled where used.

Gaps (left blank deliberately)

• Aluminum DC resistance at 20 °C — the entire column is blank. No open manufacturer table publishing aluminum resistance at 20 °C by AWG/kcmil size was found: Southwire and Cerro publish aluminum DC resistance at 25 °C in their spec sheets, and the familiar NEC Chapter 9 tables are at 75 °C (and the NEC document is not a source for this dataset). Per the published-numbers-only rule, aluminum resistance was not derived from the copper values by ratio and not computed from Essex's published aluminum constant.
• 700, 800, and 900 kcmil: not listed in Service Wire's bare-copper table or Southwire SPEC 45001 stock sizes, so diameter, resistance, and weight are blank (area, which is definitional for kcmil sizes, and the published mm² conversion are filled).
• kcmil diameter in mm: not published in the sources used — blank (unit conversion is the engine's job, not the dataset's).
• Bare-copper weight, AWG 13 and 15–40: not published in the sources consulted — blank.
• Ampacity above 750 kcmil and below 14 AWG: outside the scope of the source table as republished for this dataset.

Licensing note

Values are factual data points transcribed with attribution from manufacturers' openly published tables and charts, per the Toolchest rule: facts from open publications, named source per row, no wholesale copying of any proprietary compilation, and the NEC/NFPA document itself was not used as a source.