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  • Do it yourself - How to wire a GFCI electrical outlet.

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       Wiring Home > Electrical > Electrical Outlets > Ground Fault Electrical Outlet

    This section covers do it yourself wiring of an GFCI electrical outlet. A GFCI outlet is different from conventional outlets. In the event of a ground fault, a GFCI will trip and quickly stop the flow of electricity to prevent serious injury.

    The National Electrical Code requires that outlets in wet locations be ground fault protected. You will need to use a GFCI outlet in the following locations; The Bathroom, All Kitchen Counter top outlets, All Garages and sheds, Basements and Outside outlets. In addition outlets that are outside must be in a weather proof enclosure.

    Definition of a ground fault:
    Instead of following its normal safe path, electricity passes through a person's body to reach the ground. For example, a defective appliance can cause a ground fault.

    A GFCI outlet does NOT protect against circuit overloads, short circuits, or shocks. For example, you can still be shocked if you touch bare wires while standing on a non-Conducting surface, such as a wood floor.

    Checking to see if an existing receptacle is functioning properly is easy with an inexpensive GFCI tester.

    Electric Shock Caution: To prevent severe shock or electrocution always turn the power OFF at the service panel before working with wiring.

    Never Assume the power is off! Always double check, and test the device before you begin work.

    After turning the power off to the circuit, the next thing you will need to do is Identify the Cables/Wires. If you are wiring a new outlet, you will already know which wire is the Line and which is the Load. If you are going to replace an existing outlet, you will need to to pay close attention to this part.

    LINE Cable:
    Delivers power from the service panel (breaker panel or fuse box) to the GFCI outlet. This cable should be connected to the GFCI's LINE terminals only.

    LOAD Cable:
    Delivers power from the GFCI outlet to another outlet in the circuit. This Cable should be connected to the GFCI's LOAD terminals only.

    If there is only one cable entering the electrical box, it is the LINE cable. This cable should be connected to the GFCI's LINE terminals only.

    Procedure to install a GFCI in a existing box with 2 cables (4-6 wires).
    1) Turn off power.

    2) Remove outlet from box while keeping the wires attached to the outlet.

    3) Detach one cable's white wire and black wire from the outlet. Cap off each removed wire separately with a wire nut. Make sure that they are from the same cable.

    4) Re-install the outlet in the electrical box, attach the face plate, than turn the power ON at the service panel.

    5) Plug in a lamp or radio and determine if power is flowing to the outlet. If so, the capped wires are the LOAD wires. If not, the capped wires are the LINE wires.

    6) Turn the power OFF at the service panel, label the LINE and LOAD wires, then detach the wires from the outlet.

    7) Connect the LINE cable wires to the LINE terminals, the white wire to the silver terminal and the black wire to the brass terminal.

    8) Connect the LOAD cable wires to the LOAD terminals, the white wire to the silver terminal and the black wire to the brass terminal.

    9) Connect the ground wires from both cables together with a wire nut and another short piece of ground wire, connect the short piece of ground wire to the green terminal on the GFCI.

    10) Fasten the GFCI back into the electrical box, and install the face plate.

    Note: If the electrical box is metal, you will also need to connect a ground wire from the wire nut to a green ground screw that is attached to the electrical box.

    GFCI electrical outlet diagram

    If you miswired the GFCI it may not prevent personal injury or death due to a ground fault (electrical shock).

    If you mistakenly connect the LINE wires to the LOAD terminals, the GFCI will still operate like an ordinary outlet, but will not interrupt a ground fault.

    Now Test your work.
    1) Turn the power ON at the service panel.

    2) Press the reset button fully.

    3) Plug in a lamp or radio to the GFCI (and leave it plugged in) to verify that the power is ON.

    4) Press the TEST button in order to trip the device. This should stop the flow of electricity, making the lamp or radio shut OFF.

    5) If this works, you are done. Press the RESET button on the device to turn power back ON.

    Did your test work?
    If the test does not work, or if you are still having problems. You will need to contact a qualified electrician in your area.

    More Tips:
    1) Make sure all devices and splices are in a UL listed electrical box of the proper size.

    2) Make sure you attach the ground wire to all metal boxes and all devices, with the proper ground screw.

    3) Twist wires together with pliers, before you put the wire nut on. Double check to insure that the connection is tight, and that no copper is showing.

    4) Always use the screws for termination of wires. Never use the holes in the back of a device for the connection, unless they clamp down with the screw.

    5) Make sure to use the proper size wire for the ampere draw of the circuit. See wire size section, for more information.

    6) Purchase a GFCI Receptacle with Safelock Protection.

    If you are having problems, Play it Safe.
    Make sure you check the regulations in the National Electrical Code regarding the device you are wiring. If you are still unsure of how to properly wire the circuit you are working on, you will need to contact a qualified electrician in your area. You can also ask questions in our forum.

    Related Sections: Basic Electrical Outlet > 220 volt Devices

    Related Resources:

  • National Electrical Code Handbook
  • National Electrical Codebook
  • Stallcup's Illustrated Code Changes
  • The Complete Guide to Home Wiring (Black and Decker Complete Guides Series)
  • Wiring Simplified
  • Guide to Using the National Electrical Code
  • Residential Remodeling and Repair Professional Reference
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      Back to the Top >Wiring Home > Electrical > Electrical Outlets > Ground Fault Electrical Outlet

    It is important to note that electrical codes change, and that in some areas local electrical codes are not the same as the National Electrical code. The local authority having jurisdiction in your area may have different codes than the national code. It is important to find out if your local codes differ from the national code, your local authority having jurisdiction is the final judge and jury.

    Disclaimer: You understand that you are personally responsible for your own wiring, and that you're wiring should conform to the National Electrical code. The information provided is general installation advice. We make no claims about the completeness or the accuracy of the information as it may apply to an infinite amount of field conditions. It is the responsibility of the person or persons using this information to check with all concerned parties, owners and local authorities, etc. before doing an installation. Users of this information agree to hold Wireityourself.com or any of its agents harmless form liabilities of any kind relating to the use of this information. You also agree to the terms set forth in our terms and conditions.