4/0 AWG Wire — Ampacity, Conduit Fill & Dimensions
Everything the code tables say about 4/0 AWG conductors on one page: ampacity by temperature rating, breaker limits, conduit fill, physical size, resistance and voltage-drop distances.
4/0 AWG copper carries 195 A at 60°C, 230 A at 75°C and 260 A at 90°C.
4/0 AWG ampacity
| Copper | Aluminum | |||||
|---|---|---|---|---|---|---|
| Installation | 60°C | 75°C | 90°C | 60°C | 75°C | 90°C |
| Raceway, cable or earth — Table 310.16 | 195 | 230 | 260 | 150 | 180 | 205 |
| Single conductor in free air — Table 310.17 | 300 | 360 | 405 | 235 | 280 | 315 |
Typical use: 230 A in copper; 4/0 aluminum is the standard 200 A residential service-entrance conductor.
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, 4/0 AWG is the minimum for circuits protected at up to 1600 A; in aluminum, up to 1000 A. See the grounding conductor table.
4/0 AWG conduit fill
| Conduit | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 4" |
|---|---|---|---|---|---|---|---|---|---|
| EMT | — | — | 1 | 1 | 1 | 4 | 7 | 11 | 18 |
| PVC Schedule 40 | — | — | 1 | 1 | 1 | 4 | 6 | 9 | 15 |
| PVC Schedule 80 | — | — | 1 | 1 | 1 | 3 | 5 | 8 | 14 |
| Rigid Metal Conduit | — | — | 1 | 1 | 1 | 4 | 6 | 9 | 16 |
| IMC | — | — | 1 | 1 | 2 | 4 | 6 | 9 | 17 |
| Flexible Metal Conduit | — | — | 1 | 1 | 1 | 4 | 6 | 8 | 15 |
| Liquidtight Flexible Metal Conduit | — | — | 1 | 1 | 1 | 4 | 6 | 9 | 15 |
| ENT | — | — | 1 | 1 | 1 | 4 | — | — | — |
Mixing sizes or using another insulation? Use the conduit fill calculator.
4/0 AWG dimensions
| Insulation | Diameter (in) | Diameter (mm) | Area (in²) | Area (mm²) |
|---|---|---|---|---|
| THHN, THWN, THWN-2 | 0.642 | 16.31 | 0.3237 | 208.8 |
| XHHW, XHHW-2, XHH | 0.638 | 16.21 | 0.3197 | 206.3 |
| TW, THW, THHW, THW-2 | 0.688 | 17.48 | 0.3718 | 239.9 |
| RHH, RHW, RHW-2 (with outer covering) | 0.778 | 19.76 | 0.4754 | 306.7 |
4/0 AWG voltage drop
| Load | 120 V 1-phase | 240 V 1-phase | 208 V 3-phase | 480 V 3-phase |
|---|---|---|---|---|
| 80 A | 370 ft | 740 ft | 740 ft | 1709 ft |
| 100 A | 296 ft | 592 ft | 592 ft | 1367 ft |
| 125 A | 236 ft | 473 ft | 474 ft | 1093 ft |
| 150 A | 197 ft | 394 ft | 395 ft | 911 ft |
| 200 A | 148 ft | 296 ft | 296 ft | 683 ft |
Based on 0.0608 Ω per 1000 ft for stranded copper at 75°C (0.1 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 4/0 AWG wire carry?
4/0 AWG copper is rated 195 A at 60°C, 230 A at 75°C and 260 A at 90°C when run in conduit or cable. Aluminum is rated 150, 180 and 205 A. Most terminations are rated 75°C, so the 75°C figure is the one normally used.
What size conduit do I need for 4/0 AWG wire?
Three 4/0 AWG THHN conductors need at least 2-inch EMT. Add the ground wire’s area and check the chart above for larger bundles.
What is the diameter of 4/0 AWG wire?
The bare conductor is 211,600 circular mils (107.22 mm²). With THHN insulation the overall diameter is about 0.642 in (16.31 mm) and the area is 0.3237 in², which is the figure used for conduit fill.
How far can I run 4/0 AWG wire?
For a 3% voltage drop on a 240 V single-phase circuit carrying 200 A, about 296 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.