Electrical Wiring and Electrical Repairs

GFCI Outlet Wiring Method

gfci outlet
Summary: This article and the electrical wiring diagram will show you how to install a GFI using the feed through method which will protect more than one outlet.

GFI Wiring Diagram using the Feed Through Method to Protect Outlets

A typical application for this method would be to protect more than one bathroom, or the all of the receptacles in your garage.

Below you will see some photos of recent projects that I have selected to help you with your project.

The GFCI Receptacle will have LINE and LOAD areas to attach your wires to. The "LINE" is the set of wires coming from the panel or power source, the "LOAD" is the wire set leaving the receptacle box to the other downstream receptacles to be controlled by the GFCI.

Protecting more than One Receptacle from One GFCI

This method is used when installing the GFCI as the first receptacle and wiring it so that it provides protection for all of the receptacles downstream on the circuit.

A typical application for this method would be to protect more than one bathroom, or the all of the receptacles in your garage.

Below you will see some photos of recent projects that I have selected to help you with your project.

The GFCI Receptacle will have LINE and LOAD areas to attach your wires to. The "LINE" is the set of wires coming from the panel or power source, the "LOAD" is the wire set leaving the receptacle box to the other downstream receptacles to be controlled by the GFCI.

Take a look at a typical Feed-Thought Installation
[Click on the images to Enlarge]

check local code reqs
GFCI Feed Through Wiring 1
Pre-wiring for the feed through method
GFCI Feed Through Wiring 2
GFCI Feed Through Wiring 3
GFCI Feed Through Wiring 4
Label the romex electrical wire
supplying the power.
Folding the wires in
until installation.
This junction box is ready for the GFCI.
GFCI Feed Through Wiring 5
GFCI Feed Through Wiring 6
GFCI Feed Through Wiring 7
To install: fold wires out.
Identify the set to
be used for the LINE feed.
Identify the LINE area of the
GFCI Receptacle.
GFCI Feed Through Wiring 8
GFCI Feed Through Wiring 9
GFCI Feed Through Wiring 10
Remove the Yellow Warning sticker to expose the LOAD Area and Terminals.
First attach the
LINE Black wire to the LINE Hot Wire terminal, and the
LINE White wire to the LINE White Wire Terminal.
Now attach the
LOAD Black wire to the LOAD Hot Wire terminal, and the
LOAD White wire to the LOAD White Wire Terminal.
GFCI Feed Through Wiring 11
GFCI Feed Through Wiring 12
GFCI Feed Through Wiring 13
Fold the wires carefully back inside the receptacle box and install the GFCI receptacle.
Mount the GFI cover plate.
After all the downstream receptacles have been installed, the circuit is turned on and tested at all locations.

More about GFCI Wiring


Overloaded GFI Outlet

Question:Chad, from Louisville, Kentucky asks:
I recently installed a new electrical outlet on a kitchen wall that previously had none. I basically ran the new wire down to our basement and tapped into an existing box that is running two additional outlets. I flipped the power on, plugged in the toaster oven and microwave and the clocks on both power up. However, when I run either of the two appliances, they tend to work for about 1-2 minutes and then stop. It doesn't trip the breaker, but the outlet simply quits working. Without doing anything, the outlet will turn itself back on after about 10 minutes or so (I know this as the clocks on the appliances power back up). I tried replacing the outlet with a GFI outlet and the same thing occurs only this time it does trip the GFI. Could it be the fact that I have plugged in two appliances that surge which is causing this to happen? Why would they work for a bit and then stop but then work again? I am very confused. Thanks. Chad

Answer:My first thought is to identify the circuit that you have tapped into and find out where that circuit originates from and if there could be any problems occurring with that circuit. As for the GFCI outlet, I have experienced where GFI outlets can act like a circuit breaker if the load that is passing though is too great. GFCI outlets do not do well when they are overloaded. You have not mentioned, but it may be that the GFI outlet is rated for 15 amps and the circuit is actually a 20 amp circuit. If this is the case then installing a 20 amp rated GFI outlet may solve the problem. Dave

How Many Outlets Can Connect to the first GFCI Outlet

Question: Using the feed through method, is there a limit on either the number of downstream receptacles or the distance beyond the GFCI outlet?

Answer: You can add any reasonable number of outlets, the concern is to stay within the amperage load of the circuit, distance is not a problem as long as your under 200 feet, depending on the connected types of load placed on the circuit. Dave

Double Quad Outlets Protected by GFCI

Question:This feed through is really good, but how would I wire it if it were a quad with a GFCI in the first position to protect all 3 standard down stream outlets? I would like to put in two quads. Would it be Line in from feed to GFCI, load out to second outlet (standard - non GFCI)in same box; then wire out from this standard non-GFCI to the second quad (2x standard non-GFCI)? Do I just use short wires to connect the outlets in each quad together? Thanks, Dan

Answer: Yes Dan, It's basically the same wiring as shown except that you are wiring the LOAD side out to all your outlets and they may be connected by making jumper wires or tails from each set to one connection for the LOAD Set of wires.


The Difference between a 15 Amp and 20 Amp GFCI

Question: Rob asks: How can I tell if the GFI outlet is a 15 or 20 amp outlet? Does it say on the outlet?

Answer: Yes - the GFCI Outlet should have a label or impression which states the voltage and amperage. You will also notice that on a 20 amp GFCI Outlet the left or neutral plug opening will have both the vertical and horizontal opening for a 20 amp plug. You may notice that with some brands of 15 amp GFCI Receptacles have a 20 amp rated feed through, therefore a 15 amp GFCI receptacle may be installed on a 20 amp circuit.

GFI Outlets Feeding Other Outlets

Question: Charlie Asks: I have seen the square outlets that have the same shape as a GFI. When installing downstream outlets from a GFI should these be used? This is new construction in Indiana. Thanks Charlie.

Answer: Dave's Reply: The square design that you are referring to for the other outlets is just a different decorative design and really does not have any significance to GFCI protection that is provided by the GFI outlet. The design of the GFI outlet was adopted most likely because of the extra space that was needed for the ground fault circuit components.

Hot Tub on a GFCI Outlet Circuit

Question: I hooked a GFCI receptacle to an existing circuit and it trips every once in a while. The GFCI is rated for 20 amps and it is protecting my new 12 amp hot tub. I replaced the GFCI, but still getting occasional tripping of the GFCI! Could the new hot tub be a lemon? Steve

Answer: Keep in mind that the existing circuit rating should be identified. Check to see if the hot tub requires it's own dedicated circuit. Sharing a circuit with a hot tub could cause nuisance tripping of a GFCI outlet if the circuit is loaded up to capacity. The hot tub could be tested for possible inconsistencies, and it may help to search for feedback about the reliability of the unit as well. Dave

More about Wiring a GFCI Outlet

  • My Outlets Are Dead – Should I Replace The GFCI?

  • Fully explained wiring instructions complete with a picture series of GFCI installations and wiring diagrams can be found here…

  • GFCI Outlets and Aluminum Wire

  • How to Safely Wire GFCI Outlets: Creating a Copper Pig Tail with Aluminum Wire, Working with Aluminum Wire, Splicing Aluminum Wire, Anti-Corrosion Ointment for Aluminum Wire, Attaching Aluminum Wire, AL/CU Rated Outlets and Switches.

  • How To Wire a GFCI and Outlet to a Light Switch

  • Fully explained wiring instructions complete with a picture series of an installation and wiring diagrams can be found here in the GFI and Light Switch area here in this website. Just click the Wiring Diagrams….

  • Wiring a GFCI Outlet with a Switch

  • How to Wire a GFCI Outlet with a Switch – There are a few different methods that are used to wire GFI Outlets but all start with locating the Line side of the GFCI Receptacle where the power source is attached as described.

  • Hairdryer Outlet and GFI Safety Requirement

  • Electrical Protection Requirements for a Hairdryer Near a Sink – Keep in mind that if this outlet will be within 6 feet of a sink then the outlets require GFI protection.

Learn more about Wiring a GFCI Outlet


Share Your Comment or Question


Comments (5)

Installing One GFI for Each Bathroom
The builder at my house installed one GFCI for all 4 bathrooms, but every time 2 people use two bathrooms at once with a hair dryer, the GFCI outlet trips. Can I install 4 separate GFCI's without too much trouble?
Thank you,

Sure Steve, take a look at the Tailed Wiring Method for installing a separate GFCI outlet at each bathroom. This should take care of the problem.

#1 - Steve - 04/28/2014 - 14:37
GFCI in a 2 Wire System
I am putting in GFCI outlets in a two-wire system with no ground. I read that about the line and load part. So basically I put the power coming IN to the LINE on the left side and top (lets just use these for easy reasons) then the other wire going to the other plugs goes on the LOAD side (bottom and right) correct?

Hi Ian,
Yes, the LINE connections are for the Circuit Power Source, and the LOAD connections are used when supplying power to additional devices.
#2 - Ian - 11/11/2014 - 11:41
Wiring a Bathroom GFCI and Exhaust Fan
I'm trying to wire up a bathroom. I have the new power line running to a light switch with a ceiling fan light combo. It is a double switch meaning one switch is for the light and one for the exhaust fan. Then I tried to feed from this light switch to a GFCI that has a switch on top (for vanity light) and outlet on bottom and I can't get the GFCI unit to work. From this GFCI outlet I want to run to another GFCI with two outlets. What am I doing wrong?

Hi Melinda,
The GFCI outlet requires the Line In and Load Out circuit wiring to be connected properly, otherwise the GFCI outlet will not function correctly.
#3 - melinda morris - 03/26/2015 - 03:20
Wiring a GFCI Outlet in the Kitchen
I want to hook up a GFCI outlet in the kitchen. Currently there are three outlets on the counter. Each have traveling legs off the load. Which outlet can I install the GFCI on? I do not see a outlet that either starts or ends with only two wires in it. THANKS
#4 - Steve DeThomas - 04/16/2015 - 16:14
Water Will Trip a GFCI
Comment on hot tub GFCI. If there is any leakage around the seal for the heating element, The conductivity of the water WILL cause the GFCI to trip off.

Rick, Maintenance Supervisor

Thank You Rick, Great Information.
#5 - Rick - 04/28/2015 - 15:36

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