2/0 AWG Wire — Amp Rating, Ampacity & Diameter
Ampacity, geometry, resistance, conduit fill and maximum run length for 2/0 AWG conductors in copper and aluminium.
Quick answer
Copper 75 °C
170A
Aluminium 75 °C
133A
Diameter
0.3648in
Circular mils
133,077
Full specification
| Size designation | 2/0 AWG |
|---|---|
| AWG gauge number | 2/0 |
| Circular mils | 133,077 |
| kcmil | 133.08 |
| Bare diameter (in) | 0.3648 |
| Bare diameter (mm) | 9.266 |
| Cross-section (mm²) | 67.43 |
| THHN/THWN-2 OD (in) | 0.532 |
| Insulated area (sq in) | 0.2223 |
| Copper resistance (Ω/1000 ft) | 0.0779 |
| Aluminium resistance (Ω/1000 ft) | 0.1277 |
| Max standard breaker (Cu, 75 °C) | 150 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 | 192 A | 175 A | 157 A | 136 A |
| 6 | 154 A | 140 A | 125 A | 109 A |
| 9 | 134 A | 123 A | 110 A | 95 A |
| 15 | 96 A | 88 A | 78 A | 68 A |
| 25 | 86 A | 79 A | 71 A | 61 A |
Source & method: The governing value is also capped by the termination rating, commonly 75 °C, which for this size is 170 A. Run your own conditions.
Maximum run length at 3% voltage drop
One-way distance for 2/0 AWG copper before drop exceeds 3%.
| Load | 120 V 1Ø | 240 V 1Ø | 208 V 3Ø | 480 V 3Ø |
|---|---|---|---|---|
| 10 A | 1,856 ft | 3,713 ft | 3,716 ft | 8,576 ft |
| 15 A | 1,237 ft | 2,475 ft | 2,477 ft | 5,717 ft |
| 20 A | 928 ft | 1,856 ft | 1,858 ft | 4,288 ft |
| 30 A | 618 ft | 1,237 ft | 1,238 ft | 2,858 ft |
| 40 A | 464 ft | 928 ft | 929 ft | 2,144 ft |
| 50 A | 371 ft | 742 ft | 743 ft | 1,715 ft |
How many 2/0 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 | 2 | 3 | 6 | 10 | 15 | 20 | 26 |
| IMC | — | 1 | 1 | 2 | 4 | 6 | 9 | 14 | 19 | 24 |
| RMC | — | 1 | 1 | 2 | 3 | 6 | 8 | 13 | 18 | 23 |
| PVC Sch 40 | — | 1 | 1 | 2 | 3 | 5 | 8 | 13 | 17 | 22 |
| PVC Sch 80 | — | — | 1 | 1 | 3 | 5 | 7 | 11 | 15 | 20 |
2/0 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 | 144 A | 170 A | 192 A |
| Aluminium | 113 A | 133 A | 150 A |
The 2/0 AWG copper ampacity figure you use on a real circuit is the 75 °C column, 170 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, 192 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 (133 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 2/0 AWG with the sizes immediately above and below it before sizing a circuit.
Circuits that use 2/0 AWG
Breaker ratings whose smallest copper conductor at 75 °C terminations is 2/0 AWG.
2/0 AWG amp rating, diameter and metric equivalent
The amp rating for 2/0 AWG wire depends on the insulation temperature rating, not on the conductor alone. Copper ampacity is about 144 A on a 60 °C conductor, 170 A at 75 °C and 192 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, 2/0 AWG is 0.3648 in (9.27 mm) in bare diameter, which is 133,077 circular mils. The cross sectional area works out to 67.43 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 2/0 actually gets used
2/0 is the common aluminium 150 A service and feeder conductor and a copper 175 A feeder. In multi-family construction it is frequently the house-panel or riser feeder size, and in industrial work it appears as a motor control centre feed.
Because 2/0 aluminium and 4/0 aluminium bracket the two most common residential service ratings, 2/0 is usually chosen for a 150 A panel upgrade where the existing meter base and mast can be reused. Meter socket lug range and service-entrance cable availability, not ampacity, tend to decide the final size.
Conduit implications are significant: a set of three 2/0 conductors plus a grounding conductor generally requires 2 inch raceway at the 40 percent fill percentage. Underground runs at this size are usually pulled in PVC Schedule 40, which has less internal area than metal tubing of the same trade size and can push the design a full trade size larger.
Frequently asked
- How many amps can 2/0 AWG wire carry?
- 2/0 AWG copper is estimated at 144 A at 60 °C, 170 A at 75 °C and 192 A at 90 °C, at 30 °C ambient with no more than three current-carrying conductors. Aluminium of the same size is about 133 A at 75 °C.
- What is the amp rating for 2/0 gauge wire?
- Use 170 A for 2/0 AWG copper on equipment with 75 °C terminations, which covers most breakers and panel lugs. Read 144 A instead when the conductor is inside NM-B cable, and treat 192 A as the derating base only. Aluminium of the same size is about 133 A at 75 °C.
- What breaker size goes with 2/0 AWG copper?
- The largest standard overcurrent device that 2/0 AWG copper supports at 75 °C is 150 A. For a continuous load, the load itself must not exceed 80% of that rating.
- What is the diameter of 2/0 AWG wire?
- The bare conductor is 0.3648 inches (9.266 mm) in diameter, which is 133,077 circular mils. With THHN/THWN-2 insulation the nominal outside diameter is about 0.532 inches.
- What is the resistance of 2/0 AWG wire?
- About 0.0779 ohms per 1000 feet for copper and 0.1277 ohms per 1000 feet for aluminium, at 75 °C.
- How far can I run 2/0 AWG wire?
- Distance depends on load and voltage. At 20 A on a 120 V single-phase circuit, 2/0 AWG copper stays under 3% voltage drop for about 928 feet one-way. Doubling the voltage roughly doubles the allowable distance.
Related charts & calculators
- Rebar Size ChartBar designation, diameter, area and weight per foot.
- Socket Size ChartSAE to metric socket conversion with the closest interchangeable size.
- Pipe Thread ChartNPT nominal size, outside diameter, threads per inch and tap drill.
- Nut Size ChartBolt size to hex nut across-flats wrench size, SAE and metric.
- Allen Wrench Size ChartHex key sizes with SAE and metric cross-reference.
- Voltage Drop CalculatorPercent drop, end voltage and minimum conductor for any run length.