How to Install a 12-3 Wire 20 Amp Receptacle

A 20-amp, 240-volt receptacle is installed for small appliances, such as an air conditioner window unit, small plug-in water heater and air compressors. The device is a single receptacle, allowing only one item to plug into it. In some 240-volt wiring applications, the neutral wire is not required to complete the circuit and is dropped from the wiring of the item. The neutral wire is only necessary to complete a 120-volt circuit or used on a 240-volt circuit for appliances, such as stoves and clothes dryers where 120-volts is necessary to operate some features of the control panel of those appliances.

• 1

  Mark a location with a pencil for your 20-amp 240-volt receptacle. Trace around the template that came with your single gang remodel receptacle box with a pencil. Cut around the trace line with a keyhole saw to remove the wall board from the 20-amp receptacle location.

• 2

  Turn off the main breaker at the electrical panel to disconnect the electricity to the entire panel. Remove the cover from the panel using a screwdriver to expose the wiring and the body of the breakers.

• 3

  Pull the 12/3 nonmetallic (NM) electrical wire from the 20-amp receptacle location to the breaker panel. Pull the electrical cable through a knockout in the back of the single gang remodel receptacle box and slip the box into the wall. Twist the two screws on the remodel receptacle box clockwise until the box clamps to the wall.

• 4

  Strip the exterior sheath from the 12/3 NM electrical wire at the receptacle location with a dual NM wire cutter/stripper. Removing the exterior of the cable exposes the interior black, red, white and bare copper ground wires. Remove 3/4 inch of insulation from the black and red wires, leaving the insulation on the white wire.

• 5

  Twist an orange wire connector around the white wire and tape the wire connector to the wire with electrical tape. Push the white wire to the back of the receptacle box.

• 6

  Wrap the red wire from the 12/3 NM electrical wire around one copper screw on the side of the 20-amp 340-volt receptacle. Wrap the black wire around the remaining copper screw on the opposite side of the receptacle. Wrap the bare copper ground wire around the green ground screw and tighten all three screws with a screwdriver to hold the wires to the 20-amp receptacle.

• 7

  Cover the receptacle, electrical box and wiring with a single gang, single outlet cover plate.

• 8

  Strip the insulation from the red and black wires at the main breaker panel. Attach an orange wire connector to the white wire the same way you did in Step 5.

• 9

  Install a 20-amp double-pole breaker into the electrical panel. Slip the back of the breaker under the slot in the panel to hold the breaker in the panel. Push the front of the breaker over the center buss bar of the panel. Slip the red wire underneath a set screw at the back of the breaker, and slip the black wire underneath the remaining set screw on the breaker. Tighten the set screws with a screwdriver to hold the two wires to the breaker.

• 10

  Slide the bare copper ground wire under an empty set screw on the ground bar inside the panel. The ground bar is a thin, silver bar with all other bare and green ground wires attached to it. Tighten the set screw with a screwdriver to hold the ground wire to the bar.

• 11

  Replace the cover on the panel box and turn the main breaker on to supply power to the panel and the 12-amp, 240-volt receptacle.