What Is 240V Power and How Does It Work?

240V power in U.S. homes is the line-to-line voltage from two 120V hot wires, powering large appliances like dryers and EV chargers.

For the full breakdown, see our best 240V Power Station guide.

Most U.S. houses run on 120V for standard outlets, but the same service delivers 240V when you need serious wattage. Understanding what 240V power is and how it works comes down to one idea: two out-of-phase 120V legs. That distinction explains why your dryer plugs into a bigger outlet, why the voltage reads differently at the panel, and why you should never force a 120V device into a 240V receptacle.

How 240V Power Works in a U.S. Home

U.S. residential service is split-phase 120/240V AC at 60 Hz. The utility transformer feeds your panel two “hot” legs, each measuring about 120V to neutral. Because those legs sit 180 degrees out of phase, the voltage measured between them is the sum — a full 240V.

That single service feeds everything in the house:

• Standard 120V outlets use one hot leg plus neutral for lights, TVs, and small appliances.
• 240V circuits use both hot legs for high-draw equipment like ovens, dryers, water heaters, central air conditioners, and EV chargers.

Higher voltage packs more power at lower current.

Voltage Range and Common Misconceptions

The ANSI-standardized nominal voltage is 240V with a ±5% tolerance, meaning a properly fed circuit reads anywhere from 228V to 252V. That range explains why you’ll hear people swap “220V” and “240V” — older standards and real-world readings blur the line. Strictly speaking, U.S. residential service is 120/240V, not 220V.

Two other misconceptions cause real trouble:

• Not every outlet is 240V. Standard household receptacles are 120V; 240V outlets appear only for dedicated high-load appliances.
• 240V outlets are not interchangeable. A 240V range receptacle, a dryer outlet, and an EV charger port each have different plug configurations, wiring, and breaker requirements. The plug, circuit, and breaker must all match the appliance’s rating.

What 240V Power Is Used For

Residential 240V service powers fixed appliances that need heavy wattage. The most common uses include electric ranges and ovens, clothes dryers, water heaters, central air conditioning, and level 2 EV chargers. In each case, the device is hardwired or uses a dedicated receptacle rated for its exact amperage and plug style.

For most portable loads, 120V is plenty. But if you’re running power tools in a workshop or need backup power for a refrigerator and a well pump, a single 240V circuit can handle loads that would trip a standard breaker. That’s where a dedicated 240V power station becomes useful — it delivers the higher voltage for demanding equipment without relying on a wall circuit.