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 | About 155 feet one-way for 3% drop at 18.75A |
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.
10 AWG copper wire on a 30A, 240V double-pole breaker. A standard 4500W electric water heater draws approximately 18.75 amps at 240V. A dedicated circuit is required — no other loads may share it.
NEC 422.31 requires a means of disconnecting the water heater within sight of the appliance or lockable in the open position. Many water heaters include a built-in switch; otherwise, a disconnect is installed at the panel or near the unit.
No — electric water heaters require a 30A circuit with 10 AWG copper wire. Using 12 AWG wire (rated for 20A) on a 30A breaker is a code violation and fire risk. Always size wire to match the breaker.
A 4500W water heater draws 18.75A and fits on a standard 30A, 10 AWG circuit. A 5500W unit draws 22.9A and still fits within a 30A circuit's continuous load limit (30A × 80% = 24A). Both use 10 AWG copper wire and a 30A double-pole breaker.