How To Replace a GFCI

how to replace a gfci

How To Replace a GFCI

(Last Updated On: October 3, 2018)

GFCI outlets protect people from severe or fatal electric shocks. A GFCI constantly monitors the current flowing through a circuit by measuring the current flowing into the circuit compared to the returning current. As a result, homeowners should know how to replace a GFCI or understand why they are important and work with a qualified electrician to incorporate in their home.

Additionally, the National Electrical Code (NEC) requires GFCI outlets in all wet or damp locations such as:

  • Kitchens
  • Bathrooms
  • Laundry rooms
  • Basements
  • Garages
  • Workshops

Therefore, regardless of your technical know how, all homeowners must learn how and why GFCIs work and protect your family.

How GFCIs Work

In properly working appliances, the electricity flows from from hot to neutral and the GFCI monitors the amount of current flowing from hot to neutral. If there is any imbalance, it trips the circuit to stop the flow of electricity.

What does this mean?

In the US, most homes have 120-volt outlets, where there are two vertical slots (with the left slot slightly larger than the right slot) and then a round hole centered below them.

  • Left slot = “neutral”
  • Right slot =  “hot”
  • Center hole = “ground”

For example, if you are outside with a power drill completing a project as it starts raining, you are standing on the ground. The wet drill provides a path from the hot wire inside the drill through you to ground.

If electricity flows from hot to ground through you, it could be fatal.

The GFCI can sense the current flowing through you because not all of the current is flowing from hot to neutral as it expects – some of it is flowing through you to ground! As soon as the GFCI senses that, it trips the circuit and cuts off the electricity.

How to Replace a GFCI

Replacing a GFCI or any electrical outlet is not for everyone. In fact, most electrical work requires professional technicians. However, understanding the process and steps helps homeowners learn how their home operates. As a result, the team at Home Depot share how to replace a GFCI.

First, preparation. Always take all precautionary and safety steps when dealing with electricity.

  • Turn off the power before beginning your project.
  • Make sure the amp rating of your GFCI matches the amp rating of the wiring and breaker or fuse.
  • Always turn off power to a circuit before working on it and place a note on the electrical panel to warn others not to turn it on.
  • Wear rubber-soled shoes and use tools with rubber handles.
  • Don’t use a GFCI as a receptacle for a refrigerator, freezer or other appliance, as it could trip without your knowledge.

Second, turn off the power at the circuit breaker or fuse. To do so, remove the wall plate and use a tester, which verifies the power is off.

Next, remove the existing outlet. Remove mounting screws and gently pull the switch out of the wall box. Label the black and white wires on the Line and Load terminals. Finally, disconnect the wires.

Next, prepare the wires by making sure they are straight (cut if necessary). Remove insulation so ¾ inch of the copper conductor shows.

Then, identify the line wires.

  • Pull wires out of the wall box and position them so they cannot touch each other.
  • Restore power and carefully touch the black probe to the metal box or bare copper ground wire. If installing a GFCI on an ungrounded circuit, refer to the manufacturer’s instructions.
  • Place the red probe to each black wire until the tester lights up. This is the black wire that will connect to the Line brass screw terminal.
  • Leave the red probe on the black Line hot wire and place the black probe on each white wire until the tester lights up. This is the white wire that will connect to the Line silver screw terminal.
  • Turn power off.

Then, connect the wires by unscrewing the terminal screws of the new GFCI until they are difficult to turn. Next:

  • Connect the black Line hot wire to the brass screw marked Line by inserting the wire into the back-wire hole and tighten the terminal screw.
  • Connect the white Line neutral wire to the silver screw marked Line by inserting the wire into the back-wire hole and tightening the terminal screw.
  • If the outlet box has four wires plus a ground, connect the second black wire to the brass terminal marked Load and the second white wire to the silver terminal marked Load.
  • Connect the ground wire to the green ground screw by inserting the wire into the back-wire hole and tighten the terminal screw. If there are multiple ground wires, connect them together with a copper pigtail, secure with a wire nut and attach the loose end of the pigtail to the green ground screw.

Next, place the GFCI into the wall box by carefully bending the wires and pushing the GFCI into the wall box. Tighten the mounting screws to secure the GFCI to the wall box.

Finally, cover with the wall plate, restore the power and press the Reset button.

If the GFCI does not reset, the line and load leads may have been reversed during installation. Refer to the “Test Your Work” section of the manufacturer’s instruction sheet or call a qualified electrician.

For a video overview, then DIY Creators offers a tutorial.

How to Test GFCIs

First and foremost, homeowners should test all GFCIs every month.

The ESFI provides a simple video detailing GFCI testing instructions. The best way to test a GFCI is based on the manufacturer’s instructions. However, the general testing follows:

  • Plug a lamp into the outlet and turn the lamp on.
  • Press the GFCI’s test button.

Did the light go out? If not, the GFCI is not working or has not been correctly installed and you should contact a qualified electrician to correct the wiring and/or replace the defective GFCI.

If the light went out, press the reset button.

Did the light come back on? If not, replace the GFCI. If the light came back on, then the GFCI is working appropriately.

As a reminder, the ESFI advises that GFCIs should only be installed by a licensed, qualified electrician.

Do you have any questions?

SolvIt is ready to answer any questions or help install any GFCIs, so please feel free to contact SolvIt today.

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