1 AWG Wire — Amp Rating, Ampacity & Diameter
Ampacity, geometry, resistance, conduit fill and maximum run length for 1 AWG conductors in copper and aluminium.
Quick answer
Copper 75 °C
126A
Aluminium 75 °C
98A
Diameter
0.2893in
Circular mils
83,693
Full specification
| Size designation | 1 AWG |
|---|---|
| AWG gauge number | 1 |
| Circular mils | 83,693 |
| kcmil | 83.69 |
| Bare diameter (in) | 0.2893 |
| Bare diameter (mm) | 7.348 |
| Cross-section (mm²) | 42.41 |
| THHN/THWN-2 OD (in) | 0.446 |
| Insulated area (sq in) | 0.1562 |
| Copper resistance (Ω/1000 ft) | 0.1239 |
| Aluminium resistance (Ω/1000 ft) | 0.2031 |
| Max standard breaker (Cu, 75 °C) | 125 A |
Ampacity with derating
Estimated ampacity from the 90 °C column at various ambient temperatures and conductor counts.
| Conductors in raceway | 30 °C ambient | 40 °C ambient | 50 °C ambient | 60 °C ambient |
|---|---|---|---|---|
| 3 | 142 A | 130 A | 116 A | 100 A |
| 6 | 114 A | 104 A | 93 A | 80 A |
| 9 | 99 A | 91 A | 81 A | 70 A |
| 15 | 71 A | 65 A | 58 A | 50 A |
| 25 | 64 A | 58 A | 52 A | 45 A |
Source & method: The governing value is also capped by the termination rating, commonly 75 °C, which for this size is 126 A. Run your own conditions.
Maximum run length at 3% voltage drop
One-way distance for 1 AWG copper before drop exceeds 3%.
| Load | 120 V 1Ø | 240 V 1Ø | 208 V 3Ø | 480 V 3Ø |
|---|---|---|---|---|
| 10 A | 1,167 ft | 2,335 ft | 2,337 ft | 5,394 ft |
| 15 A | 778 ft | 1,557 ft | 1,558 ft | 3,596 ft |
| 20 A | 583 ft | 1,167 ft | 1,168 ft | 2,697 ft |
| 30 A | 389 ft | 778 ft | 779 ft | 1,798 ft |
| 40 A | 291 ft | 583 ft | 584 ft | 1,348 ft |
| 50 A | 233 ft | 467 ft | 467 ft | 1,078 ft |
How many 1 AWG conductors fit in conduit
Maximum count of this size alone, at the fill percentage matching the resulting count.
| Conduit | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 3-1/2" | 4" |
|---|---|---|---|---|---|---|---|---|---|---|
| EMT | 1 | 1 | 1 | 3 | 5 | 8 | 14 | 22 | 29 | 37 |
| IMC | 1 | 1 | 1 | 4 | 5 | 9 | 13 | 20 | 27 | 34 |
| RMC | 1 | 1 | 1 | 3 | 5 | 8 | 12 | 19 | 25 | 32 |
| PVC Sch 40 | — | 1 | 1 | 3 | 5 | 8 | 12 | 18 | 24 | 32 |
| PVC Sch 80 | — | 1 | 1 | 3 | 4 | 7 | 10 | 16 | 22 | 28 |
1 AWG copper ampacity vs aluminium ampacity
Ampacity by conductor material and insulation temperature rating, at 30 °C ambient with no more than three current-carrying conductors.
| Material | 60 °C (TW, NM-B) | 75 °C (THW, THWN, XHHW) | 90 °C (THHN, THWN-2, XHHW-2) |
|---|---|---|---|
| Copper | 107 A | 126 A | 142 A |
| Aluminium | 83 A | 98 A | 111 A |
The 1 AWG copper ampacity figure you use on a real circuit is the 75 °C column, 126 A, because breakers and lugs on most equipment are listed for 75 °C even when the conductor insulation is rated 90 °C. The 90 °C value, 142 A, is the starting point for ambient and conductor-count derating only — you derate from 90 °C, then cap the answer at the termination rating.
Aluminium of the same size carries roughly 78% of the copper value (98 A at 75 °C), so an aluminium feeder is normally stepped up one to two sizes to match a copper circuit. NM-B cable is always read from the 60 °C column regardless of the temperature stamped on the conductor insulation.
Source & method: Values are model estimates from conductor geometry and resistivity — see methodology and verify against the NEC edition enforced locally.
Neighbouring sizes
Compare 1 AWG with the sizes immediately above and below it before sizing a circuit.
Circuits that use 1 AWG
Breaker ratings whose smallest copper conductor at 75 °C terminations is 1 AWG.
1 AWG amp rating, diameter and metric equivalent
The amp rating for 1 AWG wire depends on the insulation temperature rating, not on the conductor alone. Copper ampacity is about 107 A on a 60 °C conductor, 126 A at 75 °C and 142 A at 90 °C, all at 30 °C ambient with no more than three current-carrying conductors in the raceway. The carrying capacity drops from there in hot spaces or crowded conduit, and terminations rated 75 °C cap what you can actually use.
Geometrically, 1 AWG is 0.2893 in (7.35 mm) in bare diameter, which is 83,693 circular mils. The cross sectional area works out to 42.41 mm², so the nearest IEC 60228 metric conductor is the next standard size at or above that figure — AWG sizes and mm² sizes never line up exactly, so round up rather than to the closest value.
American Wire Gauge (AWG) is a standard specification for the sizes of solid round wires used as electrical conductors, and the AWG number counts the drawing operations used to reach the diameter. That is why larger gauges are thinner wire and why standardized wire steps follow a fixed ratio: one AWG step changes diameter by about 12.2% and area by about 26%. Above 1 AWG the American standard continues 1/0 to 4/0, then switches to kcmil for anything larger.
Where 1 AWG actually gets used
1 AWG is another interval size, used mainly where a calculated feeder lands between 2 AWG and 1/0. In copper it serves feeders in the 130 to 150 A range; in aluminium it appears on 110 to 125 A panel feeders where the designer did not want to jump straight to 1/0.
It matters most in retrofit work. When an existing raceway cannot be enlarged, 1 AWG sometimes buys the ampacity needed to reuse the conduit where 1/0 would not fit at the applicable fill percentage. That single geometric fact is why the size survives on drawings at all.
Termination hardware is the other consideration: many 100 to 125 A panel main lugs are listed over a range that ends near 1 AWG or 1/0, so the panel label, not the conductor table, decides whether a given size can legally land there.
Frequently asked
- How many amps can 1 AWG wire carry?
- 1 AWG copper is estimated at 107 A at 60 °C, 126 A at 75 °C and 142 A at 90 °C, at 30 °C ambient with no more than three current-carrying conductors. Aluminium of the same size is about 98 A at 75 °C.
- What is the amp rating for 1 gauge wire?
- Use 126 A for 1 AWG copper on equipment with 75 °C terminations, which covers most breakers and panel lugs. Read 107 A instead when the conductor is inside NM-B cable, and treat 142 A as the derating base only. Aluminium of the same size is about 98 A at 75 °C.
- What breaker size goes with 1 AWG copper?
- The largest standard overcurrent device that 1 AWG copper supports at 75 °C is 125 A. For a continuous load, the load itself must not exceed 80% of that rating.
- What is the diameter of 1 AWG wire?
- The bare conductor is 0.2893 inches (7.348 mm) in diameter, which is 83,693 circular mils. With THHN/THWN-2 insulation the nominal outside diameter is about 0.446 inches.
- What is the resistance of 1 AWG wire?
- About 0.1239 ohms per 1000 feet for copper and 0.2031 ohms per 1000 feet for aluminium, at 75 °C.
- How far can I run 1 AWG wire?
- Distance depends on load and voltage. At 20 A on a 120 V single-phase circuit, 1 AWG copper stays under 3% voltage drop for about 583 feet one-way. Doubling the voltage roughly doubles the allowable distance.
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