How to Wire a 220 Outlet

In the United States, most electronic devices plug into wall outlets that provide 120 volts of electricity. But large appliances, such as clothes dryers, stoves and air conditioners may require 220 volts. To add a large appliance to your home, you may need to first install a 220-volt wall outlet. You may want to hire a qualified electrician to add the supply wires and breaker to the breaker box. Once that's done, wiring the outlet is relatively simple.


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    Check with the national and local electrical codes. Make sure you understand all the requirements for wiring a 220-volt outlet.
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    Choose the correct wire size and type for the appliance. A label should give the amperage rating of the appliance, and this will determine the wire size. An example would be a 20 Amp air conditioner requiring a 12 gauge wire, typically a 3 wire plus ground Romex cable.
    • Consult the manufacturer's information to discover how much current the appliance will draw. Make sure the wire you use is rated for 20 percent more.
    • Use copper wire only. If you use aluminum wire, you will need to make sure all of the connections are suitable for aluminum.
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    Locate your outlet less than 200 feet (61.0 m) of the panel box. This will prevent a voltage drop that you would have to correct.
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    Determine whether to use 3 conductors or 4 conductors. If you are replacing an older appliance, you may have to convert your outlet from 3 to 4 conductors using a pigtail. It's not necessary to rewire the connection and install a new outlet, but you may choose to do so.
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    Install an outlet even if you can directly connect the appliance to the breaker box. In order to use a direct connection, the appliance must be within 50 feet (15.2 m) and within sight of the breaker box or you must install a disconnect. Since a plug and outlet are a disconnect, you may as well go ahead and install the outlet.
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    Hire a qualified electrician to connect the supply wire to the breaker box. This is dangerous work that must be done without disconnecting power. If you attempt to do this yourself and make a mistake, you could receive a fatal shock.
    • Appliances using 220 volts are connected to a double pole circuit breaker, which is two circuit breakers connected together. This allows the appliance to use both phases of the incoming electrical power, and to trip at the same time, removing power to the appliance. If you don't use a double pole breaker, then both breakers may not trip, and the malfunctioning appliance will still have power, which can be dangerous.
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    Make sure the breaker is turned off.
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    Run the supply wires behind the wall to the outlet location. You will have to cut holes in the drywall, chisel space for the wires in the wall studs and use a fish tape to pull the wire along.
    • You should have already measured and cut the hole in the drywall for the outlet.
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    Cut the wires to the correct length for the outlet. The wires for a 220-volt outlet are too stiff to allow you to simply stuff any extra into the wall.
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    Strip off about 2 inches (5 cm) of the insulating jacket on the wires. Use a utility knife. Be careful not to cut the inner insulation.
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    Strip off about 1/2 inch (1.25 cm) of the inner insulation to expose the wire. Use wire strippers to do this.
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    Connect the wires to the outlet. Study the outlet and connect the wires to the terminals either by pushing them into the terminals or bending them around a screw and tightening the screw.
    • Four-conductor outlets have 3 terminals corresponding to the vertical slots on the left, right and top-center, and a terminal corresponding to the rounded bottom slot.
    • The black wire is "hot" and connects to one of the terminals on the left or right. It makes no difference which side you connect the black wire to.
    • The red wire is also "hot" and connects to the other left or right terminal. In 3-conductor connections, there is no red wire.
    • The white wire is neutral and connects to the top terminal.
    • The bare wire is ground and connects to the terminal corresponding to the bottom, rounded slot.
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    Test your connections to make sure they're correct. Turn on the breaker and use a voltmeter or multimeter.
    • The voltage between the left and right terminals should be 220.
    • The voltage between the left or right terminal and the neutral terminal should be 110.
    • The voltage between the neutral and ground terminal should be 0.
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    Turn off the breaker, assemble the outlet and install it in the wall.

Things You'll Need

  • Wire cutters
  • Utility knife
  • Wire strippers
  • Screwdriver
  • Outlet receptacle
  • Fish tape

Article Info

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