How Many Amps Does a Whole-House Fan Use?

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.

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.

Measure what a whole-house fan actually draws

The figures above are typical ratings, and this load is usually hardwired or on a 240 V circuit, so a plug-in meter can't reach it. A clamp meter reads the current on one conductor at the disconnect or panel without breaking the circuit; opening a panel is work for someone qualified, and the voltage pen confirms a circuit is dead first.

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Clamp meter

Fluke 323

Best for: Measuring what a hardwired circuit actually draws, even in a crowded panel

Check price on Amazon: Fluke 323 (opens in a new tab)(paid link)

Non-contact voltage tester

Klein Tools NCVT-3P

Best for: Confirming a circuit is dead before you open a device or box

Check price on Amazon: Klein Tools NCVT-3P (opens in a new tab)(paid link)

Frequently asked questions

Amp draw of other appliances

• Space Heater13 A
• Window Air Conditioner10 A
• Central Air Conditioner15 A
• Heat Pump13 A