1/0 AWG Wire — Ampacity, Conduit Fill & Dimensions
Everything the code tables say about 1/0 AWG conductors on one page: ampacity by temperature rating, breaker limits, conduit fill, physical size, resistance and voltage-drop distances.
1/0 AWG copper carries 125 A at 60°C, 150 A at 75°C and 170 A at 90°C.
1/0 AWG ampacity
| Copper | Aluminum | |||||
|---|---|---|---|---|---|---|
| Installation | 60°C | 75°C | 90°C | 60°C | 75°C | 90°C |
| Raceway, cable or earth — Table 310.16 | 125 | 150 | 170 | 100 | 120 | 135 |
| Single conductor in free air — Table 310.17 | 195 | 230 | 260 | 150 | 180 | 205 |
Typical use: 150 A feeders in copper; the smallest size permitted to be run in parallel.
Use the column that matches the lowest temperature rating in the circuit — usually the 75°C terminations on breakers and lugs. The 90°C column is a starting point for derating, not a rating you can load the wire to. NM-B (Romex) cable is always limited to the 60°C column.
As a copper equipment grounding conductor, 1/0 AWG is the minimum for circuits protected at up to 800 A; in aluminum, up to 500 A. See the grounding conductor table.
1/0 AWG conduit fill
| Conduit | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 4" |
|---|---|---|---|---|---|---|---|---|---|
| EMT | — | 1 | 1 | 3 | 4 | 7 | 12 | 19 | 32 |
| PVC Schedule 40 | — | 1 | 1 | 3 | 4 | 7 | 10 | 15 | 27 |
| PVC Schedule 80 | — | 1 | 1 | 2 | 3 | 6 | 9 | 14 | 24 |
| Rigid Metal Conduit | — | 1 | 1 | 3 | 4 | 7 | 10 | 16 | 27 |
| IMC | — | 1 | 1 | 3 | 4 | 8 | 11 | 17 | 29 |
| Flexible Metal Conduit | — | 1 | 1 | 2 | 4 | 7 | 10 | 15 | 27 |
| Liquidtight Flexible Metal Conduit | — | 1 | 1 | 3 | 4 | 7 | 10 | 16 | 27 |
| ENT | — | 1 | 1 | 3 | 4 | 7 | — | — | — |
Mixing sizes or using another insulation? Use the conduit fill calculator.
1/0 AWG dimensions
| Insulation | Diameter (in) | Diameter (mm) | Area (in²) | Area (mm²) |
|---|---|---|---|---|
| THHN, THWN, THWN-2 | 0.486 | 12.34 | 0.1855 | 119.7 |
| XHHW, XHHW-2, XHH | 0.482 | 12.24 | 0.1825 | 117.7 |
| TW, THW, THHW, THW-2 | 0.532 | 13.51 | 0.2223 | 143.4 |
| RHH, RHW, RHW-2 (with outer covering) | 0.622 | 15.80 | 0.3039 | 196.1 |
1/0 AWG voltage drop
| Load | 120 V 1-phase | 240 V 1-phase | 208 V 3-phase | 480 V 3-phase |
|---|---|---|---|---|
| 60 A | 245 ft | 491 ft | 492 ft | 1135 ft |
| 80 A | 184 ft | 368 ft | 369 ft | 851 ft |
| 100 A | 147 ft | 295 ft | 295 ft | 681 ft |
| 125 A | 118 ft | 236 ft | 236 ft | 545 ft |
| 150 A | 98 ft | 196 ft | 196 ft | 454 ft |
Based on 0.122 Ω per 1000 ft for stranded copper at 75°C (0.201 Ω for aluminum). For other loads and lengths use the voltage drop calculator.
All wire sizes
- 14 AWG
- 12 AWG
- 10 AWG
- 8 AWG
- 6 AWG
- 4 AWG
- 3 AWG
- 2 AWG
- 1 AWG
- 1/0 AWG
- 2/0 AWG
- 3/0 AWG
- 4/0 AWG
- 250 kcmil
- 300 kcmil
- 350 kcmil
- 400 kcmil
- 500 kcmil
- 600 kcmil
- 700 kcmil
- 750 kcmil
- 800 kcmil
- 900 kcmil
- 1000 kcmil
Frequently asked questions
How many amps can 1/0 AWG wire carry?
1/0 AWG copper is rated 125 A at 60°C, 150 A at 75°C and 170 A at 90°C when run in conduit or cable. Aluminum is rated 100, 120 and 135 A. Most terminations are rated 75°C, so the 75°C figure is the one normally used.
What size conduit do I need for 1/0 AWG wire?
Three 1/0 AWG THHN conductors need at least 1-1/4-inch EMT. Add the ground wire’s area and check the chart above for larger bundles.
What is the diameter of 1/0 AWG wire?
The bare conductor is 105,600 circular mils (53.51 mm²). With THHN insulation the overall diameter is about 0.486 in (12.34 mm) and the area is 0.1855 in², which is the figure used for conduit fill.
How far can I run 1/0 AWG wire?
For a 3% voltage drop on a 240 V single-phase circuit carrying 150 A, about 196 feet one way in copper. Halve that at 120 V. Lighter loads go proportionally farther.
NECTables.com is an independent reference and is not affiliated with, endorsed by, or a substitute for the National Fire Protection Association (NFPA). NEC® and National Electrical Code® are registered trademarks of the NFPA. Values shown are commonly published engineering data and independent calculations based on the methods of NFPA 70; they are not a reproduction of the Code. Always confirm against the edition adopted in your jurisdiction, including local amendments, and consult a licensed electrician or engineer before doing electrical work.