How Many Amps Does a Whole-House Fan Use?
Whole-House Fan 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, a whole-house fan 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 — a whole-house fan
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.
Whole-House Fan amperage at 120 V and 240 V
Same 400 W load — the current halves when the voltage doubles. Whole-House Fan 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 a whole-house fan
At 3.3 A, a whole-house fan 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.
Frequently asked questions
Ask AI about this
Open an AI assistant with a question grounded in this page.