GFCI Outlets, How To Wiring Diagram

GFCI outlets and wiring diagramDo you have a question about wiring a GFCI outlet? You can consult with our in-office electricians in Mesa Arizona free of charge. Available today, Wednesday, May 27th, 2020, from 8:00 AM until 5:00 PM, our Mesa AZ electricians will explain how to wire a GFCI outlet and answer all of your GFCI receptacle wiring questions. Give our local Mesa electricians a call; they will save you both time and money. Free estimates are also available.

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How To Wire GFCI Outlets

Wiring a GFCI receptacle is a little more complicated than hooking up a regular outlet but easily learned once explained. You can also learn about wiring GFCI outlets in the following 7 steps.

Note: If you are replacing an existing GFCI outlet with a new one we suggest that you read our page about replacing a GFCI outlet.

Tools Needed

  • Flashlight
  • Phillips Head Screwdriver
  • Slotted Screwdriver
  • Wire Strippers
  • Voltage Tester

Materials Needed

  • GFCI Outlet
  • 2 yellow wire nuts
Step 1: Turn Circuit Breaker Off
  1. At the circuit breaker box or fuse box, turn off the electrical power.
  2. Remove the attached finish plate.
  3. Confirm that the power is shut off with a voltage tester. Do not depend on the circuit breaker labels, often times these are mislabeled.
Step 2: Take Out the Existing Electrical Outlet
  1. Remove the 2 mounting screws that are securing the existing electrical outlet and pull it all the way out of the box.
  2. Disconnect the attached wires on the existing electrical outlet from the terminal screws.
Step 3: Prepare the Wires So They Can Be Reconnected To the New GFCI Outlet
  1. Cut the ends off the wiring (the previously connected portion) and straighten them.
  2. Strip off about ¾ of an inch of insulation from each conductor for the new connections.
Step 4: Identify the Hot Conductors (Line Side)

Note: If only 1 black, 1 white and 1 green or bare wire are present in the electrical outlet box you can skip past this step.

  1. Pull the wires out of the electrical box and separate all black and white conductors so no one can contact another. Your green or bare conductors can and should remain spliced together.
  2. Turn the power back on and using your voltage tester, carefully touch the black probe to the ground wire.
  3. Using the red probe on your voltage tester, touch each black wire until you find the live one. This is the identified hot wire and it will get attach on the line side brass terminal screw on your new GFCI outlet.
  4. Keeping the red probe in contact with the identified hot black wire, remove the other probe from the ground and touch each individual white conductor until voltage is detected again. This will be the identified white wire and it will get attached on the line side silver terminal screw on your new GFCI outlet.
  5. Carefully cap off the ends of each of these identified conductors with your yellow wire nuts. Do not put any wires together, the power is still on!
  6. Turn all electrical power off again.
Step 5: Terminate the Conductors

Note: Line and load will be clearly labeled on the back of the GFCI outlet and often times the load side will be covered with a piece of tape. Refer to the diagram above about wiring GFCI receptacles for additional help.

  1. Loosen the silver and brass terminal screws on the line side of the outlet. If more than 1 black and 1 white conductor are in the electrical box, also loosen the load side silver and brass terminal screws.
  2. Take the black hot wire (the identified black one with the yellow wire nut on it). It gets attached on the line side brass screw.
  3. Take the identified white wire (the white wire with the yellow wire nut on it). It gets attached on the line side silver screw.
  4. Take any remaining black wires and attach them on the load side brass screw.
  5. Take any remaining white wires and attach them on the load side silver screw.
  6. Take the bare or green wire and attach it to the green screw on the GFCI outlet. You may have to splice these ground conductors together and add a small piece of wire to the splice. This is often referred to as a pigtail and it attaches to the ground screw.
Step 6: Insert The New Outlet into the Electrical Box
  1. Fold the ground conductor into the electrical box first. It is best to try to position the ground furthest back in the box to avoid any unintentional short circuiting to the terminal screws.
  2. Next fold the white and black wires into the box. Try to keep the white conductors on the side of the box where the silver screws of the outlet will be and the black conductors on the brass screw side of the box. This will keep the conductors from crossing behind the outlet and leave you with more space for the outlet.
  3. Insert the outlet completely into the electrical box and tighten down the mounting screws.
  4. Attach the finish cover plate.
Step 7: Turn All Electricity Back On
  1. Turn your circuit breakers back on. This should restore electrical power to the new GFCI outlet but it will not work until the reset button is pushed.
  2. Press the reset button to activate the outlet.

Note: If the circuit breaker won’t reset or trips, it indicates a problem with the line side conductors behind the receptacle. Double check steps 5 and 6 and inspect the line side black conductor for damage.

Note: If the reset button will not reset make sure the line and load wires are terminated properly as described in step 5. Also inspect the load side black and white conductors for damage and make sure the ground conductor is not coming into contact with any other screws on the receptacle.

About Wiring to Line and Load on the Receptacle Diagram

The back of these outlets are clearly marked line and load. It is important to know which is which before beginning. They usually come from the factory with a piece of tape covering the load connection points for further identification. Refer to the attached GFCI outlet wiring diagram above for clarity or contact our in-office electrician in Mesa AZ free of charge.

  • Line side connections:

    The line terminals of a GFCI outlet connect to the power supply conductors that are connect at the circuit breaker or fuse box. Line essentially means supply. The line wires are the incoming hot conductors. In most residential applications a Romex cable will be used which will include a bare (ground), white (neutral) and black (hot) conductor. GFCI outlet requirements mandate that line terminals identified by color require the white line conductor (neutral) to connect to the silver line terminal and the black line conductor (hot) to connect to the brass line terminal.

  • Load side connections:

    The load terminals of a GFCI outlet can be used to connect additional outlets to the same GFCI protected power. Load essentially means using the protected power (opposed to supplying the power). Load terminals identified by color require the white load conductor or conductors to connect to the silver load terminal and the black load conductor or conductors to connect to the brass load terminal.

Ground fault circuit interrupters (GFCI’s) implement line and load connections to employ an automatic trip action when a difference of electricity is detected. This is why it is imperative to put the correct wires on the correct screws. If any conductor is not correctly attached to the correct screw, the GFCI outlet will not work.

Learn about replacing a GFCI outlet Learn what to do if a GFCI outlet keeps tripping Learn where GFCI outlets belong Learn about installing GFCI outlets

How to ground fault circuit interrupter receptacle wiring diagrams

How to wire a single ground fault circuit interrupter diagram Diagram about wiring a ground fault circuit interrupter's load side to other devices with ground fault protection How to wire a ground fault circuit interrupter receptacle to other receptacles without protection diagram

Visit us at tips for common electrical problems in houses for additional help.


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