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.
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.
| Draw | Watts | Amps at 120 V | Amps at 240 V |
|---|---|---|---|
| Running | 400 W | 3.3 A | 1.7 A |
| Starting (surge) | 900 W | 7.5 A | 3.8 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.
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