1/0 AWG Wire Specs
Ampacity, geometry, resistance, conduit fill and maximum run length for 1/0 AWG conductors in copper and aluminium.
Quick answer
1/0 AWG copper carries about 146 A at 75 °C (124 A at 60 °C, 165 A at 90 °C). The bare conductor is 0.3249 in (8.25 mm) and 105,535 circular mils, with 0.0983 Ω per 1000 ft. It pairs with a 125 A breaker at 75 °C terminations.
Copper 75 °C
146A
Aluminium 75 °C
114A
Diameter
0.3249in
Circular mils
105,535
Full specification
| Size designation | 1/0 AWG |
|---|---|
| AWG gauge number | 1/0 |
| Circular mils | 105,535 |
| kcmil | 105.53 |
| Bare diameter (in) | 0.3249 |
| Bare diameter (mm) | 8.252 |
| Cross-section (mm²) | 53.49 |
| THHN/THWN-2 OD (in) | 0.486 |
| Insulated area (sq in) | 0.1855 |
| Copper resistance (Ω/1000 ft) | 0.0983 |
| Aluminium resistance (Ω/1000 ft) | 0.1611 |
| Max standard breaker (Cu, 75 °C) | 125 A |
Published standard — source: Geometry computed from the ASTM B258 AWG formula; resistance from standard resistivityFormula estimate — source: Ampacity from the site model
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 | 165 A | 151 A | 135 A | 117 A |
| 6 | 132 A | 121 A | 108 A | 93 A |
| 9 | 115 A | 105 A | 94 A | 82 A |
| 15 | 83 A | 75 A | 67 A | 58 A |
| 25 | 74 A | 68 A | 61 A | 52 A |
Source & method: The governing value is also capped by the termination rating, commonly 75 °C, which for this size is 146 A. Run your own conditions.
Maximum run length at 3% voltage drop
One-way distance for 1/0 AWG copper before drop exceeds 3%.
| Load | 120 V 1Ø | 240 V 1Ø | 208 V 3Ø | 480 V 3Ø |
|---|---|---|---|---|
| 10 A | 1,472 ft | 2,945 ft | 2,947 ft | 6,801 ft |
| 15 A | 981 ft | 1,963 ft | 1,964 ft | 4,534 ft |
| 20 A | 736 ft | 1,472 ft | 1,473 ft | 3,400 ft |
| 30 A | 490 ft | 981 ft | 982 ft | 2,267 ft |
| 40 A | 368 ft | 736 ft | 736 ft | 1,700 ft |
| 50 A | 294 ft | 589 ft | 589 ft | 1,360 ft |
How many 1/0 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 | 3 | 4 | 7 | 12 | 19 | 24 | 31 |
| IMC | — | 1 | 1 | 3 | 4 | 7 | 11 | 17 | 22 | 29 |
| RMC | — | 1 | 1 | 3 | 4 | 7 | 10 | 16 | 21 | 27 |
| PVC Sch 40 | — | 1 | 1 | 3 | 4 | 7 | 10 | 15 | 20 | 27 |
| PVC Sch 80 | — | 1 | 1 | 2 | 3 | 6 | 8 | 13 | 18 | 24 |
Neighbouring sizes
Frequently asked
- How many amps can 1/0 AWG wire carry?
- 1/0 AWG copper is estimated at 124 A at 60 °C, 146 A at 75 °C and 165 A at 90 °C, at 30 °C ambient with no more than three current-carrying conductors. Aluminium of the same size is about 114 A at 75 °C.
- What breaker size goes with 1/0 AWG copper?
- The largest standard overcurrent device that 1/0 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 1/0 AWG wire?
- The bare conductor is 0.3249 inches (8.252 mm) in diameter, which is 105,535 circular mils. With THHN/THWN-2 insulation the nominal outside diameter is about 0.486 inches.
- What is the resistance of 1/0 AWG wire?
- About 0.0983 ohms per 1000 feet for copper and 0.1611 ohms per 1000 feet for aluminium, at 75 °C.
- How far can I run 1/0 AWG wire?
- Distance depends on load and voltage. At 20 A on a 120 V single-phase circuit, 1/0 AWG copper stays under 3% voltage drop for about 736 feet one-way. Doubling the voltage roughly doubles the allowable distance.
Materials for this size
Materials for this size
Wire, cable and terminations for 1/0 AWG.
- THHN/THWN-2 1/0 AWG copper1/0 AWG copperBuilding wire in the size this page covers (1/0 AWG copper).Check price on Amazon →
- NM-B cable 1/0 AWG1/0 AWGRomex-type cable for dry indoor branch circuits at this size.Check price on Amazon →
- Wire connectors for 1/0 AWG1/0 AWGPush-in or twist-on connectors rated for this conductor size.Check price on Amazon →
- Terminal lugs & anti-oxidantCopper-rated mechanical lugs for panel and disconnect terminations.Check price on Amazon →
Links go to Amazon search results, not a single listing — confirm ratings, insulation type and listing details before buying, and make sure the part is approved for your application.
Related charts & calculators
- Voltage Drop CalculatorPercent drop, end voltage and minimum conductor for any run length.
- Conduit Fill CalculatorFill percentage and maximum conductor count for EMT, RMC, IMC and PVC.
- Breaker Size CalculatorOvercurrent device rating and minimum conductor from load current.
- Wire Ampacity CalculatorDerated ampacity for ambient temperature and bundled conductors.
- Box Fill CalculatorVolume allowances for conductors, clamps, devices and grounds per NEC 314.16.
- Ampacity ChartEstimated allowable ampacity by conductor size, material and insulation rating.