Wire Size for 40 Amp 300 Feet (120V)
| Standard | Wire Size | Ampacity | Volt Drop | Drop % |
|---|
| NEC (US) | AWG 1/0 (53.5 mm²) | 150 A | 2.87 V | 2.39% |
| IEC (EU) | 50 mm² | 144 A | 3.07 V | 2.56% |
| BS (UK) | 35 mm² | 119 A | 4.38 V | 3.65% |
| AS/NZS | 35 mm² | 119 A | 4.38 V | 3.65% |
About AWG 1/0
- Typical use
- 125–150 A service entrance — residential main service
- Max breaker
- 150 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 2 | 33.6 mm² | 115 A | 2.85% |
| 40 A | AWG 1/0 | 53.5 mm² | 150 A | 2.39% |
| 50 A | AWG 1/0 | 53.5 mm² | 150 A | 2.99% |
Adjacent Distance Comparison
| Distance | AWG | mm² | Ampacity | Drop % |
|---|
| 200 ft | AWG 2 | 33.6 mm² | 115 A | 2.54% |
| 300 ft | AWG 1/0 | 53.5 mm² | 150 A | 2.39% |