How Many Amps Is 4,500 Watts?

Answer
37.5 A at 120 V · 18.8 A at 240 V

Amps = watts ÷ volts. A 4,500 W resistive load draws 37.5 A at 120 V and 18.8 A at 240 V. That is too much for a 120 V circuit, so loads this size run on 240 V.

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1.0 for heaters and lights; 0.8–0.9 for motors.
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    For estimating and educational purposes only. Results are approximate and are not a substitute for a licensed professional, the manufacturer's instructions or your local code. Disclaimer

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    Amps, breaker and wire by voltage

    VoltageCurrentBreaker (continuous)Copper wire
    120 V37.5 AUse 240 V–
    208 V21.6 A30 A10 AWG
    240 V18.8 A25 A10 AWG
    480 V 3-phase5.41 A––

    Breaker sized at 125% for continuous loads (NEC 210.20). Motors and electronics draw more current than watts ÷ volts because of power factor.

    Frequently asked questions

    Can a 15 amp circuit handle 4,500 watts?

    No. A 15 A circuit at 120 V supplies at most 1,800 W. Use a 20 A circuit (up to 2,400 W) or a 240 V circuit.

    How many amps is 4,500 watts at 12 volts?

    375 A at 12 V DC, before inverter losses (about 417 A through a 90% efficient inverter).

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