How to Convert a 240 Electrical Outlet to 120

House remodeling work may involve relocating a 120-volt circuit to an area currently occupied by a 240-volt appliance. If an electric clothes dryer is replaced by a gas dryer, for instance, a 120-volt circuit will be needed to operate the drum and timer. Whatever the reason, a 240-volt electrical outlet can be converted to a 120-volt outlet.

• 1
  Voltage tester voltage image by Tadzio from Fotolia.com

  Open the breaker box and locate the 240-volt circuit breaker that is the source for the 240-volt receptacle in question. This is most easily managed if one person switches the breakers off and on while another person checks the 240-volt reading at the receptacle. When the 240 volts drops to zero, the circuit is identified.

  Double-check to be sure it is the right breaker by checking that the 240-volt reading switches on and off with the breaker. Place a piece of tape on the breaker for identification.

  Turn the breaker off.

• 2

  Remove the breaker panel cover by removing the four screws, one located at each corner. Be careful not to lose these hard-to-find screws; the screw threads are unique to these panel covers, but they may be located at large home building supply stores.

• 3

  Remove the the cover that is placed over the 240-receptacle that is to be changed. The cover is usually chrome-plated and is held in place with four screws. The receptacle will be held to the box with four screws as well. Remove the screws and pull the receptacle out of the box. The electrical wires will be stiff, so bend them as necessary to get the receptacle out.

• 4

  Loosen the screws securing the wires to the 240-volt receptacle. Remove the wires. Set the 240-volt receptacle aside. Let the wires protrude from the box, being careful that the wires do not touch each other nor the metal box.

• 5

  Turn the breaker back on.

• 6

  Check the voltage between pairs of wires at the electrical box. There will be one pair of wires that reads 240 volts between them. If there is a third wire, it is a ground.

  Check the two "hot" wires for 120 volts between each wire and the box. If there is a 120-volt reading, then the box is grounded.

• 7
  An electric meter will have a switch located by the box. electricity meter image by Charles Jacques from Fotolia.com

  Go to the electrical meter box. There should be a switch on or below the box that will cut off the power to the building. Switch the power off and, for your safety, go into the building and switch the lights on and off to be sure that all power is turned off.

• 8

  Loosen the two screws holding the wires to the 240-volt breaker in the open breaker panel and remove the wires. Remove the 240-volt breaker by lifting the side where the wires were attached and pull out the breaker. Pry out the breaker with a screwdriver if the breaker is difficult to remove. There will now be two loose wires in the panel, one black and the other probably will be red.

• 9

  Wrap the red wire with white electrical tape all the way to where it enters the breaker panel. This identifies the wire as a neutral. All neutral wires are white. Neutral wires are connected to the center tap on the transformer in the street and are at ground potential. Black and red wires carry high voltage. The black wire does not need to be wrapped for identification.

• 10

  Connect the wire wrapped with white tape to the neutral bus bar where all the white neutral wires are connected.

  Install the new 120-volt breaker in the panel by inserting the end into the clip at one end and then pushing down on the screw end until the breaker is seated on the main bus bar.

  Attach the black wire by slipping it under the screw and tightening the screw.

  Turn the breaker on.

• 11

  If both wires are black, then tape one of them white and connect it to the neutral terminal bar. It can be identified later when the power is turned on.

  Go back to the switch by the electrical meter and turn it on.

• 12

  Test the voltage between the "hot" wires and the previously identified ground at the receptacle box. The wire that reads zero volts to ground is the new neutral wire. Identify this wire with a piece of white tape.

  Turn the new 120-volt breaker off.

• 13

  Check to see if the old wires entering the receptacle box are larger than #12. If this is the case, the heavy gauge wires will not fit the120-volt receptacle screws. Large wires must be spliced to #12 wires with wire nuts or screw clamp splices. Tape uninsulated splices with black electrical tape.

  Wrap the neutral completely with white tape.

  Connect a #12 green ground wire to the metal box. If the box is not grounded, connect it to the ground wire in the box.

• 14

  Connect the #12 hot, neutral, and ground wires to a receptacle. Install the receptacle and add the plastic cover plate.

  Replace the cover on the breaker box by replacing the four screws. Turn on the breaker.