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How Many Amps Does an Evaporative (Swamp) Cooler Use?

Evaporative (Swamp) Cooler draws about 3.3 amps at 120 volts (400 watts running) and briefly spikes to around 7.5 amps at startup. At 3.3 A, an evaporative cooler fits comfortably on a standard 15 A or 20 A household circuit.

Voltage

Amps = watts ÷ volts. Enter the wattage from your appliance's nameplate or label for an exact figure.

Current draw: an evaporative cooler

3.3 A

At 120 V
400 W
Typical breaker
15 A

Breaker figure is guidance for a simple resistive load, sized at 125% for continuous running; confirm against the nameplate and a licensed electrician.

Evaporative (Swamp) Cooler amperage at 120 V and 240 V

Same 400 W load: the current halves when the voltage doubles. Evaporative (Swamp) Cooler is typically a 120 V appliance in US homes.

DrawWattsAmps at 120 VAmps at 240 V
Running400 W3.3 A1.7 A
Starting (surge)900 W7.5 A3.8 A

The startup surge lasts a fraction of a second; it matters for generator sizing and breaker trip curves, not for your electric bill.

Breaker and circuit for an evaporative cooler

At 3.3 A, an evaporative cooler fits comfortably on a standard 15 A or 20 A household circuit. For a dedicated circuit, guidance is a 15 A breaker with 14 AWG copper (75°C terminations), sized at 125% of the running current because it runs 3+ hours at a time (NEC 210.20).

Guidance only: actual circuit sizing depends on your unit's nameplate, wire run length, and local code. Confirm with a licensed electrician. See the wire & breaker size chart for the full NEC ampacity table.

Measure what an evaporative cooler actually draws

The figures above are typical ratings. A plug-in power meter between the outlet and the cord shows the real amps and watts with nothing opened up. A clamp meter reads one conductor at a time, so it is the tool for hardwired and 240 V circuits; clamped around a whole cord it reads close to zero.

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Frequently asked questions

Evaporative (Swamp) Cooler typically draws about 3.3 amps at 120 volts, based on a typical rating of 400 watts (amps = watts ÷ volts). Because it has a motor or compressor, it briefly pulls around 7.5 amps at startup. Check the nameplate on your specific unit: ratings vary by model.

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