Standard 4500W electric water heaters draw about 18.75 amps at 240V and require a dedicated 30-amp circuit.
| Recommended wire | 10/2 NM-B or 10 AWG THHN |
| Breaker | 30A double-pole |
| Voltage | 240V |
| Typical amperage | 18.75A |
| Circuit amperage | 30A |
| NEC reference | NEC 422.13 |
| Max recommended distance | 50 feet (without voltage drop concerns) |
Water heaters are considered continuous loads, so the circuit must be rated at 125% of the actual load. 18.75A × 1.25 = 23.4A, fitting within a 30A breaker.