Wire Size for 40 Amp 10 Feet (120V)
| Standard | Wire Size | Ampacity | Volt Drop | Drop % |
|---|
| NEC (US) | AWG 8 (8.37 mm²) | 50 A | 0.61 V | 0.51% |
| IEC (EU) | 6 mm² | 41 A | 0.85 V | 0.71% |
| BS (UK) | 6 mm² | 41 A | 0.85 V | 0.71% |
| AS/NZS | 6 mm² | 41 A | 0.85 V | 0.71% |
About AWG 8
- Typical use
- 40–50 A circuits — electric ranges, large A/C, hot tubs
- Max breaker
- 50 A
- Temperature rating
- 75 °C
- NEC reference
- NEC Table 310.16
Always verify local code requirements. Wire sizing depends on insulation type, ambient temperature, and conduit fill.
Adjacent Current Comparison
| Current | AWG | mm² | Ampacity | Drop % |
|---|
| 30 A | AWG 10 | 5.26 mm² | 35 A | 0.61% |
| 40 A | AWG 8 | 8.37 mm² | 50 A | 0.51% |
| 50 A | AWG 8 | 8.37 mm² | 50 A | 0.64% |
Adjacent Distance Comparison
| Distance | AWG | mm² | Ampacity | Drop % |
|---|
| 10 ft | AWG 8 | 8.37 mm² | 50 A | 0.51% |
| 25 ft | AWG 8 | 8.37 mm² | 50 A | 1.27% |