8 AWG wire specifications: 3.2636 mm diameter, 8.3656 mm² area, 40A ampacity (copper, 75°C). Resistance, weight, and common uses.
| Diameter | 3.2636 mm · 0.12849" · 128.49 mils |
| Cross-sectional area | 8.3656 mm² · 16,510 circular mils |
| Resistance (copper, 20°C) | 2.0608 Ω/km · 0.6281 Ω/1000ft |
| Resistance (aluminum, 20°C) | 3.1677 Ω/km · 0.9655 Ω/1000ft |
| Ampacity — copper 60°C | 40 A |
| Ampacity — copper 75°C | 40 A |
| Ampacity — copper 90°C | 55 A |
| Ampacity — aluminum 75°C | 30 A |
| Weight (copper) | 74.955 kg/km · 50.368 lbs/1000ft |
| Weight (aluminum) | 22.587 kg/km · 15.178 lbs/1000ft |
| Closest metric size | 8.4 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 |