3 AWG Wire — Ampacity, Conduit Fill & Dimensions
Everything the code tables say about 3 AWG conductors on one page: ampacity by temperature rating, breaker limits, conduit fill, physical size, resistance and voltage-drop distances.
3 AWG copper carries 85 A at 60°C, 100 A at 75°C and 115 A at 90°C.
3 AWG ampacity
| Copper | Aluminum | |||||
|---|---|---|---|---|---|---|
| Installation | 60°C | 75°C | 90°C | 60°C | 75°C | 90°C |
| Raceway, cable or earth — Table 310.16 | 85 | 100 | 115 | 65 | 75 | 85 |
| Single conductor in free air — Table 310.17 | 120 | 145 | 165 | 95 | 115 | 130 |
Typical use: 100 A feeders in copper at 75°C terminations.
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, 3 AWG is the minimum for circuits protected at up to 400 A. See the grounding conductor table.
3 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 | 6 | 8 | 13 | 24 | 36 | 60 |
| PVC Schedule 40 | 1 | 1 | 3 | 6 | 8 | 13 | 19 | 30 | 51 |
| PVC Schedule 80 | 1 | 1 | 3 | 5 | 7 | 12 | 17 | 26 | 46 |
| Rigid Metal Conduit | 1 | 1 | 3 | 6 | 8 | 14 | 20 | 31 | 53 |
| IMC | 1 | 1 | 4 | 6 | 9 | 15 | 21 | 32 | 56 |
| Flexible Metal Conduit | 1 | 1 | 3 | 5 | 7 | 13 | 20 | 29 | 51 |
| Liquidtight Flexible Metal Conduit | 1 | 1 | 3 | 6 | 8 | 13 | 20 | 30 | 52 |
| ENT | 1 | 1 | 3 | 6 | 8 | 13 | — | — | — |
Mixing sizes or using another insulation? Use the conduit fill calculator.
3 AWG dimensions
| Insulation | Diameter (in) | Diameter (mm) | Area (in²) | Area (mm²) |
|---|---|---|---|---|
| THHN, THWN, THWN-2 | 0.352 | 8.94 | 0.0973 | 62.8 |
| XHHW, XHHW-2, XHH | 0.350 | 8.89 | 0.0962 | 62.1 |
| TW, THW, THHW, THW-2 | 0.380 | 9.65 | 0.1134 | 73.2 |
| RHH, RHW, RHW-2 (with outer covering) | 0.440 | 11.18 | 0.1521 | 98.1 |
3 AWG voltage drop
| Load | 120 V 1-phase | 240 V 1-phase | 208 V 3-phase | 480 V 3-phase |
|---|---|---|---|---|
| 40 A | 183 ft | 367 ft | 367 ft | 848 ft |
| 50 A | 146 ft | 293 ft | 294 ft | 678 ft |
| 60 A | 122 ft | 244 ft | 245 ft | 565 ft |
| 80 A | 91 ft | 183 ft | 183 ft | 424 ft |
| 100 A | 73 ft | 146 ft | 147 ft | 339 ft |
Based on 0.245 Ω per 1000 ft for stranded copper at 75°C (0.403 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 3 AWG wire carry?
3 AWG copper is rated 85 A at 60°C, 100 A at 75°C and 115 A at 90°C when run in conduit or cable. Aluminum is rated 65, 75 and 85 A. Most terminations are rated 75°C, so the 75°C figure is the one normally used.
What size conduit do I need for 3 AWG wire?
Three 3 AWG THHN conductors need at least 1-inch EMT. Add the ground wire’s area and check the chart above for larger bundles.
What is the diameter of 3 AWG wire?
The bare conductor is 52,620 circular mils (26.66 mm²). With THHN insulation the overall diameter is about 0.352 in (8.94 mm) and the area is 0.0973 in², which is the figure used for conduit fill.
How far can I run 3 AWG wire?
For a 3% voltage drop on a 240 V single-phase circuit carrying 100 A, about 146 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.