Every time you plug something into a wall receptacle, you’re leveraging the awesome power of the electron to power your video games and chill your beverages—which makes knowing something about those outlets an important aspect of home ownership. Plugging an appliance into the wrong receptacle or replacing one with an incorrect choice is an easy way to destroy your property and injure yourself, after all—so here are 9 receptacles you might encounter in your house that you should know about.
Outlets, receptacles, amps, and volts
Everyone knows what you mean when you say you’re going to plug something into an outlet, but technically the outlet is a location where you have access to wiring. The spot where you install a light fixture is an outlet. A receptacle is where a plug is inserted. In practice, people use them pretty interchangeably.
Power receptacles are described in terms of amperage (amps) and voltage (volts). You don’t really need to know too much about this in your role as Person Who Wants Their Toaster to Stop Tripping the Circuit Breaker, but it matters because your appliances and devices all need specific amps and volts to operate correctly and safely. You can think of volts as the “strength” of the electricity, kind of like water pressure—the force that’s pushing the power along—and amps as the “speed” or volume of the electricity. Some appliances need a lot of electricity very fast, some need less at a slower rate. Plugging them into the wrong receptacle can be exciting! But also very dangerous.
Ungrounded
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If you have power outlets in your home with just two prongs, your home’s electric infrastructure is old and needs some attention. These plugs lack a grounding prong and they’re pretty dangerous because any kind of short circuit can send electricity flowing into you if you touch it, and can even cause fires if they spark. They stopped being standard in the 1960s and were prohibited outright in the early 1970s, so even if yours have been working perfectly for years, you should seriously consider replacing them.
15 amps, 110/120 volts
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This three-pronged receptacle is the most common one you’ll find in your house, providing 110 or 120 volts of power with a maximum current of 15 amps to a long list of standard devices and small appliances like phone chargers, computers, toasters, and lamps. The bottom prong is the ground, which is what prevents electricity from leaping out of your power receptacle. And if you see a face here, it’s a phenomenon called pareidolia.
20 amps, 120/125 volts
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These outlets have a top left prong that looks like a letter “T” on its side. They provide slightly zippier amperage for appliances that draw more power than most, like your microwave oven. The amp and voltage ratings are top ends, though, so you can also plug in devices that need less power.
20 amps, 240/250 volts
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Larger appliances (like an electric stove) that need more power to operate will plug into one of these. You can tell a 250-volt 20-amp plug from a 125-volt plug by the right prong, which is sideways. That means you can’t plug smaller things into this receptacle because of the higher voltage.
30 amps, 240/250 volts
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The 30-amp, 240/250-volt receptacle (third from the left on top in the image above) has two sideways prongs. It’s intended for appliances that need a lot of power. You’ll often find one installed near the windows in your home because they’re used for large window-mounted air conditioners.
30 amps, 125/250 volts
This receptacle (top line, far right in image above) has two slanted prongs and one prong that resembles a letter “L.” You’ll see these referred to as “appliance outlets” because they’re used by washers, driers, and other larger appliances in the home.
50 amps, 125/250 volts
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This is an industrial-strength power receptacle rarely found in a residence—there’s just really no need for it in the house. You might find one in the garage, or if the house has a dedicated workshop of some sort, especially if a previous owner had some serious hobbies, like welding. Chances are if you have one you won’t have a use for it.
GFCI and AFCI
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Available in a range of amperage and voltage, these receptacles look very similar and offer similar functionality, and can be identified by the reset buttons on the front of the receptacle. Ground fault circuit interrupter (GFCI) receptacles are designed to detect when the current has gone somewhere it shouldn’t (for example, into your body) and will shut down. They’re required in damp areas like kitchens and bathrooms to prevent water from shorting out the receptacle. Arc fault circuit interrupters (AFCI) don’t prevent electrical shocks, they prevent electrical fires by detecting power leaks and shutting down accordingly.
USB Outlet
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If your house is fairly new or recently had the wiring updated, you might find a USB receptacle. This is pretty straightforward: It’s a 15- or 20-amp, 120- or 125-volt receptacle that has USB connections in addition to or instead of a three-prong plug. This can be handy if you have a lot of devices that need charging.
