How to Change a Switch to a GFCI

According to the U.S. Consumer Product Safety Commission, a properly installed GFCI, or ground fault circuit interrupter, could prevent thousands of electrical shock injuries each year. A GFCI works by monitoring the electrical current, shutting off the circuit if it senses even the slightest fluctuation in the electricity. GFCIs are actually required by the National Electrical Code for most outdoor receptacles, bathroom receptacles, garage outlets, kitchen receptacles and in both crawl spaces and finished basements. When changing a switch to a GFCI, consider a combination GFCI outlet and switch so you do not lose your ability to operate your fixture from the switch.

• 1

  Turn the breaker off inside your breaker panel to disconnect electricity to your light switch.

• 2

  Remove the screws from the switch plate to take the plate off the wall, exposing the wiring and the switch.

• 3

  Place a prong from a two prong electrical tester to a black wire attached to a switch terminal screw. Place the other prong on any metal. The tester does not light when the correct breaker is turned off. Test the remaining black wire attached to the remaining terminal on the switch.

• 4

  Remove the screws from the light switch holding it to the electrical box. Loosen the two terminal screws on the side of the switch and remove the two black wires.

• 5

  Find the two white wires connected together with a wire connector inside the electrical box. Untwist the connector to disconnect the white wires. Repeat this disconnection with the two bare copper wires inside the electrical box.

• 6

  Make two black, one white and one green pigtail wire. Cut one 6-inch piece of 12 solid THHN white electrical wire, one 6-inch piece of 12 solid THHN green electrical wire and two 6-inch pieces of 12 solid THHN black electrical wire. Strip 3/4-inch of insulation off both ends of all four pigtails with a wire cutter/stripper.

• 7

  Connect the two black pigtail wires to the black power supply wire by twisting a red wire connector onto the three wires. The black power supply wire connects to the main breaker box. Connect the two white wires inside the electrical box to the white pigtail with another red wire connector. Repeat the connection with the green pigtail and the two bare copper wires.

• 8

  Turn the combination GFCI outlet and switch to where the switch is at the top and the outlet is on the bottom. Attach the green pigtail wire around the green ground screw at the bottom of the combination device and tighten it.

• 9

  Wrap the white pigtail wire around the silver screw to the left side of the GFCI outlet. Wrap one black pigtail around the brass screw on the right side of the GFCI outlet and tighten both screws.

• 10

  Push the black wire from the fixture into the opening marked "Switch Connection" on the back side of the combination device directly behind the switch. Push the remaining black pigtail wire into the remaining switch connection opening on the back of the device.

• 11

  Push all the wires, the combination GFCI outlet and switch into the electrical box. Connect the combination GFCI device to the electrical box at the top and the bottom of the box with screws provided with the combination device.

• 12

  Cover the combination GFCI outlet and switch with a GFCI outlet plate. Turn the breaker on inside the panel to power the combination GFCI outlet and switch.