4/0 AWG Wire Specs
Ampacity, geometry, resistance, conduit fill and maximum run length for 4/0 AWG conductors in copper and aluminium.
Quick answer
4/0 AWG copper carries about 230 A at 75 °C (195 A at 60 °C, 260 A at 90 °C). The bare conductor is 0.4600 in (11.68 mm) and 211,600 circular mils, with 0.0490 Ω per 1000 ft. It pairs with a 225 A breaker at 75 °C terminations.
Copper 75 °C
230A
Aluminium 75 °C
180A
Diameter
0.4600in
Circular mils
211,600
Full specification
| Size designation | 4/0 AWG |
|---|---|
| AWG gauge number | 4/0 |
| Circular mils | 211,600 |
| kcmil | 211.60 |
| Bare diameter (in) | 0.4600 |
| Bare diameter (mm) | 11.684 |
| Cross-section (mm²) | 107.22 |
| THHN/THWN-2 OD (in) | 0.642 |
| Insulated area (sq in) | 0.3237 |
| Copper resistance (Ω/1000 ft) | 0.0490 |
| Aluminium resistance (Ω/1000 ft) | 0.0803 |
| Max standard breaker (Cu, 75 °C) | 225 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 | 260 A | 237 A | 212 A | 184 A |
| 6 | 208 A | 190 A | 170 A | 147 A |
| 9 | 182 A | 166 A | 149 A | 129 A |
| 15 | 130 A | 119 A | 106 A | 92 A |
| 25 | 117 A | 107 A | 95 A | 83 A |
Source & method: The governing value is also capped by the termination rating, commonly 75 °C, which for this size is 230 A. Run your own conditions.
Maximum run length at 3% voltage drop
One-way distance for 4/0 AWG copper before drop exceeds 3%.
| Load | 120 V 1Ø | 240 V 1Ø | 208 V 3Ø | 480 V 3Ø |
|---|---|---|---|---|
| 10 A | 2,952 ft | 5,905 ft | 5,909 ft | 13,637 ft |
| 15 A | 1,968 ft | 3,936 ft | 3,939 ft | 9,091 ft |
| 20 A | 1,476 ft | 2,952 ft | 2,954 ft | 6,818 ft |
| 30 A | 984 ft | 1,968 ft | 1,969 ft | 4,545 ft |
| 40 A | 738 ft | 1,476 ft | 1,477 ft | 3,409 ft |
| 50 A | 590 ft | 1,181 ft | 1,181 ft | 2,727 ft |
How many 4/0 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 | 1 | 4 | 7 | 10 | 14 | 18 |
| IMC | — | — | 1 | 1 | 2 | 4 | 6 | 9 | 13 | 16 |
| RMC | — | — | 1 | 1 | 1 | 4 | 6 | 9 | 12 | 15 |
| PVC Sch 40 | — | — | 1 | 1 | 1 | 4 | 5 | 8 | 12 | 15 |
| PVC Sch 80 | — | — | 1 | 1 | 1 | 3 | 5 | 7 | 10 | 13 |
Neighbouring sizes
Frequently asked
- How many amps can 4/0 AWG wire carry?
- 4/0 AWG copper is estimated at 195 A at 60 °C, 230 A at 75 °C and 260 A at 90 °C, at 30 °C ambient with no more than three current-carrying conductors. Aluminium of the same size is about 180 A at 75 °C.
- What breaker size goes with 4/0 AWG copper?
- The largest standard overcurrent device that 4/0 AWG copper supports at 75 °C is 225 A. For a continuous load, the load itself must not exceed 80% of that rating.
- What is the diameter of 4/0 AWG wire?
- The bare conductor is 0.4600 inches (11.684 mm) in diameter, which is 211,600 circular mils. With THHN/THWN-2 insulation the nominal outside diameter is about 0.642 inches.
- What is the resistance of 4/0 AWG wire?
- About 0.0490 ohms per 1000 feet for copper and 0.0803 ohms per 1000 feet for aluminium, at 75 °C.
- How far can I run 4/0 AWG wire?
- Distance depends on load and voltage. At 20 A on a 120 V single-phase circuit, 4/0 AWG copper stays under 3% voltage drop for about 1476 feet one-way. Doubling the voltage roughly doubles the allowable distance.
Materials for this size
Materials for this size
Wire, cable and terminations for 4/0 AWG.
- THHN/THWN-2 4/0 AWG copper4/0 AWG copperBuilding wire in the size this page covers (4/0 AWG copper).Check price on Amazon →
- NM-B cable 4/0 AWG4/0 AWGRomex-type cable for dry indoor branch circuits at this size.Check price on Amazon →
- Wire connectors for 4/0 AWG4/0 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.