ElectricalCharts

3/0 AWG Wire Specs

Ampacity, geometry, resistance, conduit fill and maximum run length for 3/0 AWG conductors in copper and aluminium.

Quick answer

3/0 AWG copper carries about 198 A at 75 °C (168 A at 60 °C, 223 A at 90 °C). The bare conductor is 0.4096 in (10.40 mm) and 167,806 circular mils, with 0.0618 Ω per 1000 ft. It pairs with a 175 A breaker at 75 °C terminations.

Copper 75 °C

198A

Aluminium 75 °C

154A

Diameter

0.4096in

Circular mils

167,806

Full specification

Size designation3/0 AWG
AWG gauge number3/0
Circular mils167,806
kcmil167.81
Bare diameter (in)0.4096
Bare diameter (mm)10.404
Cross-section (mm²)85.01
THHN/THWN-2 OD (in)0.581
Insulated area (sq in)0.2651
Copper resistance (Ω/1000 ft)0.0618
Aluminium resistance (Ω/1000 ft)0.1013
Max standard breaker (Cu, 75 °C)175 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 raceway30 °C ambient40 °C ambient50 °C ambient60 °C ambient
3223 A204 A182 A158 A
6178 A163 A146 A126 A
9156 A143 A127 A110 A
15112 A102 A91 A79 A
25100 A92 A82 A71 A

Source & method: The governing value is also capped by the termination rating, commonly 75 °C, which for this size is 198 A. Run your own conditions.

Maximum run length at 3% voltage drop

One-way distance for 3/0 AWG copper before drop exceeds 3%.

Load120 V 1Ø240 V 1Ø208 V 3Ø480 V 3Ø
10 A2,341 ft4,682 ft4,686 ft10,815 ft
15 A1,560 ft3,121 ft3,124 ft7,210 ft
20 A1,170 ft2,341 ft2,343 ft5,407 ft
30 A780 ft1,560 ft1,562 ft3,605 ft
40 A585 ft1,170 ft1,171 ft2,703 ft
50 A468 ft936 ft937 ft2,163 ft

Calculate your exact run

How many 3/0 AWG conductors fit in conduit

Maximum count of this size alone, at the fill percentage matching the resulting count.

Conduit1/2"3/4"1"1-1/4"1-1/2"2"2-1/2"3"3-1/2"4"
EMT—111358131722
IMC—111357111520
RMC—111357111519
PVC Sch 40—111247101418
PVC Sch 80——1124691316

Mix conductor sizes in the fill calculator

Neighbouring sizes

Smaller2/0 AWG170 A copper at 75 °C · 0.3648" diameterLarger4/0 AWG230 A copper at 75 °C · 0.4600" diameter

Frequently asked

How many amps can 3/0 AWG wire carry?
3/0 AWG copper is estimated at 168 A at 60 °C, 198 A at 75 °C and 223 A at 90 °C, at 30 °C ambient with no more than three current-carrying conductors. Aluminium of the same size is about 154 A at 75 °C.
What breaker size goes with 3/0 AWG copper?
The largest standard overcurrent device that 3/0 AWG copper supports at 75 °C is 175 A. For a continuous load, the load itself must not exceed 80% of that rating.
What is the diameter of 3/0 AWG wire?
The bare conductor is 0.4096 inches (10.404 mm) in diameter, which is 167,806 circular mils. With THHN/THWN-2 insulation the nominal outside diameter is about 0.581 inches.
What is the resistance of 3/0 AWG wire?
About 0.0618 ohms per 1000 feet for copper and 0.1013 ohms per 1000 feet for aluminium, at 75 °C.
How far can I run 3/0 AWG wire?
Distance depends on load and voltage. At 20 A on a 120 V single-phase circuit, 3/0 AWG copper stays under 3% voltage drop for about 1170 feet one-way. Doubling the voltage roughly doubles the allowable distance.

Materials for this size

Materials for this size

Wire, cable and terminations for 3/0 AWG.

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