4 AWG wire specifications: 5.1894 mm diameter, 21.1506 mm² area, 70A ampacity (copper, 75°C). Resistance, weight, and common uses.
| Diameter | 5.1894 mm · 0.204307" · 204.31 mils |
| Cross-sectional area | 21.1506 mm² · 41,741 circular mils |
| Resistance (copper, 20°C) | 0.8151 Ω/km · 0.2484 Ω/1000ft |
| Resistance (aluminum, 20°C) | 1.2529 Ω/km · 0.3819 Ω/1000ft |
| Ampacity — copper 60°C | 70 A |
| Ampacity — copper 75°C | 70 A |
| Ampacity — copper 90°C | 95 A |
| Ampacity — aluminum 75°C | 55 A |
| Weight (copper) | 189.51 kg/km · 127.345 lbs/1000ft |
| Weight (aluminum) | 57.107 kg/km · 38.374 lbs/1000ft |
| Closest metric size | 21.2 mm² |
| Skin depth at 60 Hz | 8.531 mm |
| Type | Temperature | Description |
|---|---|---|
| THHN/THWN-2 | 90°C dry / 75°C wet | Most common for building wire |
| XHHW-2 | 90°C dry and wet | Cross-linked polyethylene, moisture resistant |
| USE-2 | 90°C | Underground service entrance |
| NM-B (Romex) | 90°C | Non-metallic sheathed cable for residential |
| UF-B | 60°C | Underground feeder, direct burial |