Between its neighbours
3 AWG has 26 % more copper than 4 AWG and 21 % less than 2 AWG. Its DC resistance is 0.245 Ω per 1000 ft at 75 °C (aluminum 0.403), and 1000 ft of it carries 159.3 lb of copper.
3 AWG wire: amps, diameter & uses
3 AWG copper is 0.2294" solid (0.26" as 7-strand) and 26.7 mm². Table 310.16 rates it 85 / 100 / 115 A at 60 / 75 / 90 °C, so it protects up to a 100 A breaker on 75 °C terminals; aluminum of this size carries 75 A. Typical use: 100 A copper subpanels.
01 · 1:1 wire gauge · caliper
3 AWG · concentric stranded copper
THIS IS:
3 AWG COPPER · 100 A BREAKER · 5.83 MM COPPER
Gauge
3 AWG
concentric stranded copper
Breaker
100 A
copper, max
Measured
6.60 mm
0.2600"
The gap is 6.60 mm (0.2600"), which reads as 3 AWG concentric stranded copper. Measure bare copper for the gauge: insulation is far thicker than the metal.
- Meets NEC 2023 Table 310.16 at 75°C — verify with your local AHJ/inspector310.16
- Drawn at true sizecalibrated screen
3 AWG
- Solid diameter
- 0.229"5.83 mm · ASTM B258 formula
- Stranded (7 strands)
- 0.260"6.60 mm · Table 8
- THHN outside
- 0.352"8.94 mm · 0.0973 in² · Table 5
- Area
- 52,620 cmil26.66 mm² · nearest IEC 25 mm²
- DC resistance, 75 °C
- 0.245 Ω/1000 ftaluminum 0.403 Ω/1000 ft · Table 8
- Copper weight
- 159.3 lb/1000 ft
Ampacity
- Copper 60 / 75 / 90 °C
- 85 / 100 / 115 ANM-B uses the 60 °C column (334.80)
- Aluminum 60 / 75 / 90 °C
- 65 / 75 / 85 A
- Largest breaker (Cu, 75 °C)
- 100 Aampacity ≥ breaker
Other gauges
- Nearest SWG
- SWG 30.252" · 6.401 mm
- IEC 60228
- 25 mm²between 25 and 35 mm²
3 AWG at a glance
Size
- Solid diameter
- 0.2294" · 5.83 mm
- Stranded (7)
- 0.26"
- THHN outside
- 0.352"
- Area
- 52,620 cmil · 26.66 mm²
- Metric
- 25 – 35 mm²
- SWG nearest
- 4 (5.893 mm)
Amps
- Copper 60/75/90 °C
- 85 / 100 / 115 A
- Aluminum 75 °C
- 75 A
- Max breaker, THHN
- 100 A
- As NM-B cable
- not made
- Ground for it
- 8 AWG
Run & fit
- 120 V at 80 A
- 91 ft at 3 %
- 240 V at 80 A
- 183 ft at 3 %
- THHN in ½" EMT
- 1
- THHN in ¾" EMT
- 1
- Copper weight
- 159.3 lb/1000 ft
3 AWG reference 25 rows
Sort any column, print a shop sheet, download CSV. Click a row to load it in the calculator.
| Actions | ||||
|---|---|---|---|---|
| 734 | 7346 | 14693 | ||
| 367 | 3673 | 7346 | ||
| 146 | 1469 | 2938 | ||
| 73 | 734 | 1469 | ||
| 48 | 489 | 979 | ||
| 36 | 367 | 734 | ||
| 24 | 244 | 489 | ||
| 18 | 183 | 367 | ||
| 12 | 122 | 244 | ||
| 9 | 91 | 183 | ||
| 7 | 73 | 146 |
| Actions | |||||||
|---|---|---|---|---|---|---|---|
| 1 | 1 | 3 | 6 | 8 | 13 | ||
| 1 | 1 | 3 | 6 | 8 | 13 | ||
| 1 | 1 | 3 | 5 | 7 | 12 | ||
| 1 | 2 | 4 | 6 | 9 | 15 | ||
| 1 | 1 | 3 | 6 | 8 | 14 | ||
| 1 | 1 | 3 | 5 | 7 | 13 | ||
| 1 | 1 | 3 | 6 | 8 | 13 |
05 / Field guide
3 AWG
feeder copper.
3 AWG copper is 0.2294" solid (0.26" as 7-strand) and 26.7 mm². Table 310.16 rates it 85 / 100 / 115 A at 60 / 75 / 90 °C, so it protects up to a 100 A breaker on 75 °C terminals; aluminum of this size carries 75 A. Typical use: 100 A copper subpanels.
Feeders and services
3 AWG is the usual choice for 100 A copper subpanels. It is not made as NM-B cable; use THHN or XHHW in conduit, or SER/USE cable. The equipment ground for its largest breaker is 8 AWG.
On the 1:1 gauge
The caliper above opens at 5.83 mm. Lay a stripped length along the lines and step the gauge with ← and → until the wire just fills the gap.
Questions
Answered plainly.
01How 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 (NEC Table 310.16, 30 °C, three conductors or fewer). Aluminum of the same size: 75 A at 75 °C.
02What size breaker for 3 AWG wire?
+−
Up to 100 A with THHN on 75 °C terminals; the next size up is allowed by 240.4(B) only where the ampacity is not itself a standard rating.
03What is the diameter of 3 AWG wire?
+−
0.2294 inch (5.83 mm) solid, 0.26 inch stranded (7 strands), about 0.352 inch with THHN insulation.
04What is 3 AWG in mm²?
+−
26.66 mm² (52,620 circular mils). The IEC sizes either side are 25 and 35 mm²; replace it with 35 mm², not the smaller one.
05How far can 3 AWG wire run?
+−
At 80 A and 3 % drop, 91 ft one way at 120 V and 183 ft at 240 V (Table 8 resistance, 0.245 Ω per 1000 ft at 75 °C). Lighter loads go proportionally further.
06How many 3 AWG wires fit in ½" EMT?
+−
1 THHN conductors in ½" EMT, 1 in ¾" and 3 in 1" (NEC Chapter 9, 40 % fill for three or more).