4 kW to Amps at 120V Single-Phase AC
Exact current (Amps), real power (kW), apparent power (kVA), mechanical horsepower (HP), breaker rating, and conductor size for 4 kW on a 120V Single-Phase AC circuit.
Line Current (0.85 PF)39.22 AAt 1.0 PF: 33.33 A
Active / Apparent Power4.0 kW4.71 kVA · 2.48 kVAR
Recommended Breaker50 A (NEC)40 A (IEC Nominal)
Recommended Copper Wire8 AWGIEC Metric: 10 mm²
Engineering Breakdown for 4 kW at 120V
| Input Rating | 4 kW (120V Single-Phase AC) |
| Amperage at 0.85 Power Factor (Industrial Motor/Transformer) | 39.22 Amps |
| Amperage at 1.00 Power Factor (Resistive Load) | 33.33 Amps |
| Real Power (kW / Watts) | 4.0 kW (4,000 W) |
| Apparent Power (kVA) & Reactive Power (kVAR) | 4.71 kVA / 2.48 kVAR |
| Equivalent Mechanical Horsepower (HP) | 5.36 HP |
| NEC 125% Continuous Circuit Breaker | 50 A |
| Minimum Copper Conductor (100 ft / 30 m, ≤3% Drop) | 8 AWG (NEC) / 10 mm² (IEC) |
Frequently Asked Questions
How many amps is 4 kW at 120V (1-Phase)?
At 120V Single-Phase AC, 4 kW equals 39.22 Amps at an industrial power factor of 0.85 (or 33.33 Amps at unity power factor 1.0).
What size breaker and wire is needed for 4 kW at 120V?
For 39.22A continuous load, NEC requires a 125% rated breaker of 50A with 8 AWG copper conductors, while IEC standard sizing uses a 40A breaker with 10 mm² copper cable.
Other Power Ratings & Voltages
5 kW at 120V (1P)10 kW at 120V (1P)15 kW at 120V (1P)20 kW at 120V (1P)25 kW at 120V (1P)30 kW at 120V (1P)45 kW at 120V (1P)50 kW at 120V (1P)75 kW at 120V (1P)100 kW at 120V (1P)150 kW at 120V (1P)200 kW at 120V (1P)250 kW at 120V (1P)500 kW at 120V (1P)4 kW at 208V Single-Phase AC4 kW at 230V Single-Phase AC (IEC)4 kW at 240V Single-Phase AC (NEC)4 kW at 208V Three-Phase AC4 kW at 230V Three-Phase AC4 kW at 400V Three-Phase AC (IEC Europe)4 kW at 415V Three-Phase AC (UK / AU)4 kW at 480V Three-Phase AC (US Industrial)4 kW at 600V Three-Phase AC (Canada / Heavy)4 kW at 24V DC Direct Current4 kW at 48V DC Battery / Telecom Bus