A U.S. 240-volt plug has three or four prongs arranged by NEMA type—two hot blades plus a ground, and sometimes a neutral.
USA 240-Volt Plug Styles: What You’ll Spot At A Glance
In U.S. homes, 240-volt outlets live on split-phase service. Each circuit brings two hot legs from opposite phases, which supply 240 volts for heavy loads. Most plugs use two hot prongs and a grounding pin; some also carry a neutral so the appliance can draw 120 and 240 volts.
Shapes follow the National Electrical Manufacturers Association, or NEMA, numbering. The number before the dash marks the family and wiring, and the number after the dash marks the amperage. Once you learn a few faces, you can tell at a glance which plug fits which outlet. You can cross-check faces on the Hubbell NEMA chart.
| NEMA Type | Visual Cues | Typical Uses |
|---|---|---|
| NEMA 6-20 (20A) | 3-prong; one vertical and one horizontal flat blade plus round ground | Window A/C, shop tools, small EVSE pigtails |
| NEMA 6-30 (30A) | 3-prong; two straight flat hot blades plus round ground | Shop heaters, air compressors |
| NEMA 6-50 (50A) | 3-prong; two wide flat hot blades plus round ground | Welders, plasma cutters, garage gear |
| NEMA 10-30 (30A legacy) | 3-prong; two hots and a neutral; no equipment ground | Older dryers |
| NEMA 14-30 (30A) | 4-prong; two hots, neutral, and ground on one face | Modern dryers |
| NEMA 14-50 (50A) | 4-prong; two hots, neutral, and ground; large footprint | Ranges, RV shore power, many EV chargers |
| NEMA L6-30 (30A locking) | 3-prong; curved blades that twist into place | Generators, shop equipment |
What A 240V Plug Looks Like In The USA
Blade Count
Blade count comes first. Three-prong 240V plugs carry two hots and ground. Four-prong versions add a neutral. The ground is round or U-shaped; the neutral is a straight blade on many models, and an L-shaped blade on some 30-amp dryer styles.
Orientation
Next is orientation. On NEMA 6-20, one flat blade is vertical and the other is horizontal, which prevents mix-ups with 120-volt 5-20. On NEMA 14 variants, you’ll see two angled hot slots with a separate ground and neutral. Locking types add curved blades that twist into place after insertion.
Size
Finally, size. Higher-amp plugs are physically larger, with thicker blades and wider spacing. That sizing blocks wrong pairings.
Close Variations You’ll See Across USA 240-Volt Plugs
Dryer cords are the common case. Many laundry rooms now use a four-prong NEMA 14-30 outlet for 30-amp service. Some older spaces still have a three-prong 10-30 installed years ago. Ranges often land on a four-prong NEMA 14-50. Portable EV chargers sometimes ship with 14-50 or 6-20 adapters.
Remember the pattern: NEMA 6 families do not have a neutral; they feed straight 240 volts plus ground. NEMA 10 families are legacy three-wire designs with no separate equipment ground. NEMA 14 families carry two hots, a neutral, and a ground on one face.
How 240 Volts Reaches The Outlet
Split-Phase Overview
A typical panel feeds these outlets from a double-pole breaker that grips both hot legs. Each leg is 120 volts to neutral, and the two legs are opposite in phase, so the load sees 240 volts line-to-line. That split-phase layout keeps home wiring simple while still powering large appliances.
Loads that need both 120 and 240 get a neutral along with the two hots and ground. Think of a dryer with a control board and a heating element on the same cord. Loads that only need 240 use two hots and ground only.
Picking The Right U.S. 240V Plug For The Job
Match three things: amperage, wiring, and device needs. If the nameplate shows 240V only, a NEMA 6 series plug often fits. If the nameplate lists 120/240V, you need a plug and outlet with a neutral, usually in the NEMA 14 series.
Amperage must match the branch circuit and breaker. Dryers use 30 amps; ranges and many EV portable cords use 50 amps; shop tools vary from 20 to 50 amps. If in doubt, read the label on the appliance and the receptacle body.
Safety, Fit, And Look-alikes
Never force a plug. Similar faces can hide different ratings. A 14-30 and a 14-50 look close, yet the neutral blade differs, and the circuits behind them are different. A TT-30 looks bulky too, but it is a 120-volt RV connector, not a 240-volt plug.
Use cords with the right gauge and strain relief. Keep blades clean and straight. If an outlet is warm, loose, or discolored, stop using it and have it inspected.
Quick Visual Walkthrough By Use Case
Dryer: four-slot 14-30; three-slot 10-30 in older rooms. Range or cooktop: four-slot 14-50 in kitchens. Welder or plasma cutter: 6-50 is common. Portable EV charging often pairs with 14-50 or 6-20, depending on the adapter.
If you rent or moved into an older home, check the receptacle label. The face usually shows the NEMA code and amperage, which makes selection easy. Look closely.
How To Identify A Plug When You Only See The Face
Count prongs. Three means two hots and ground; four adds a neutral. Find the ground. The round or U-shaped opening is always ground. Check hot blade shape. Angled hot slots point to a NEMA 14 face. On a 6-20, one hot slot is vertical and the other is horizontal.
Look for the code on the plug shell or outlet yoke. Manufacturers mold the designation into the face on most devices. Labeling helps.
Why Appliances Use 240 Volts In The U.S.
Bigger heating loads and motors run better on higher voltage with lower current. That keeps current lower. Clothes dryers, ranges, some room A/C units, shop heaters, and many EV chargers all benefit from 240V service.
Federal energy guides and product sheets often call this out. You’ll also see it in appliance manuals and on the nameplate near the cord. The U.S. Department of Energy notes that large appliances often use 240 volts.
When A 240V Plug Is Not The Answer
RVs with TT-30 service are 120V only. Small countertop appliances are 120V. Electronics with external power bricks expect 120V unless marked universal input. Never adapt across voltage classes without a proper transformer and a breaker-protected circuit.
If a device ships with a special locking plug, use the matching locking receptacle. Do not shave blades or notch slots. Mechanical locks are there to protect the circuit and the user.
Pick The Match: Device, Circuit, And Plug
Use this quick chooser to align the appliance label with the branch circuit and a common U.S. 240V plug.
| Device / Use | Typical Circuit | Common Plug / Receptacle |
|---|---|---|
| Clothes dryer (modern) | 30A 120/240V two-pole | NEMA 14-30 plug with 14-30R outlet |
| Clothes dryer (older) | 30A 120/240V two-pole | NEMA 10-30 plug with 10-30R outlet (legacy) |
| Range or cooktop | 50A 120/240V two-pole | NEMA 14-50 |
| Welder / plasma cutter | 50A 240V two-pole | NEMA 6-50 |
| Window or shop A/C (larger) | 20A 240V two-pole | NEMA 6-20 |
| Air compressor or shop heater | 20–30A 240V two-pole | NEMA 6-20 or 6-30 |
| Portable EV charger (EVSE) | 20–50A 240V two-pole | NEMA 14-50 or 6-20, per adapter |
NEMA Families In Plain Language
NEMA 6
NEMA 6 means two hots and a ground at 250V max. It is the go-to family for pure 240V loads that do not need a neutral. Ratings span 15, 20, 30, and 50 amps, each with its own face that prevents a wrong match.
NEMA 14
NEMA 14 adds a neutral. That lets one cord carry both 120V and 240V to a range, dryer, or EVSE that powers controls at 120V and heaters or motors at 240V. The four prongs are two hots, a neutral, and a ground.
NEMA 10
Legacy NEMA 10 faces are still found in older homes. They have two hots and a neutral but no separate equipment ground. Many devices ship with cords that can be swapped to match the outlet that is already present.
Locking 240V Plugs You Might See
A locking connector uses curved blades. You insert and twist to latch. An L6-30 is a common 30-amp, 250V pattern on generators and shop gear. L14-30 adds a neutral for devices that split loads between 120V and 240V.
Locking devices are handy in vibration or outdoor work. If your cord end has curved blades, look for the letter L in the NEMA code.
Label Reading Tips That Save Time
Scan the nameplate on the appliance. Look for voltage, current, and whether it lists one phase with three or four wires. If it lists 125/250V, you need a neutral; if it lists 250V only, you do not. Photos help.
Match the cord cap to the outlet, not the other way around. If the receptacle face says 14-30, buy a 14-30 cord cap. Adapters exist, yet the safest path is making the appliance and the branch circuit agree.
A Note On EV Portable Chargers
Many portable EVSE units accept swappable pigtails for common plugs. A 14-50 on a 50-amp circuit gives headroom for continuous charging. Some compact EVSE models offer a 6-20 pigtail for a dedicated 20-amp, 240V circuit.
Simple Steps To Check Your Outlet Before You Buy A Cord
Read the face. Find the NEMA code, amperage, and whether it lists 125/250V or 250V only. Snap a clear photo of the outlet and label if you plan to shop for a cord or adapter.
If you need a new receptacle installed, match the circuit, cable, and device rating. A licensed electrician can evaluate load, wire size, and grounding, and can replace worn hardware.