I know how to wire a GFCI receptacle and all the things to go with it in doing so. But what I do not know is the following.

I understand the GFCI receptacle should be first in line to protect the load side going to other standard receptacles, but lets say you have 5 receptacles on a line in a room that has 2 on 1 wall a 1 on each other wall. How or what is the best way to find the first receptacle in line, so the others can be protected. Am I over thinking this? Is there a simple answer? Or do I have to take each outlet off, unwire each to find the firstvin line from the breaker?

Had a couple receptacles go bad, and have decided to replace all of them (30 total in my house and garage). Also want to install GFCIs in the circuits, just want to make sure I get them in line correctly.

  • 2
    If you're just guessing wildly which might be the first, try the one closest to the service panel. Electricians like to save money, so they often try to reduce the amount of cable used. This usually means taking the most direct route.
    – Tester101
    Commented Dec 10, 2013 at 2:08
  • 2
    If you're replacing them all anyway, disconnecting them to identify the first one isn't really any extra work. Commented Dec 10, 2013 at 3:23

4 Answers 4


There is no magic method. You disconnect an outlet and see which ones are still live, if any. You don't have to disconnect any that went dead when you did one of the others. When they are all dead, you have the most upstream outlet on this circuit in this room. If the circuit feeds multiple rooms, the problem becomes larger, but not different.

Be aware of - keep an eye out for outlets with different circuits top and bottom (generally switched one half for room lamps) they can be tricky to figure out if you don't look for them.

Another approach (NOT my favorite) would be to use GFCI breakers instead. Automatically most upstream, but also more expensive and needs to be for your particular breaker panel, rather than the generic GFCI you can put first in line and replace with another generic GFCI when it fails (they do fail.)


The problem is that each outlet (except maybe the last on the run) will have two cables, one bringing in the power, and the other taking it to another outlet. And, a non-contact voltage tester won't help because they will all show a voltage. So, the only way I know of is to disconnect the wires (just the blacks) on the one that is nearest to the circuit breaker panel, then check for power at the other outlets. If none work, you got lucky, and the power is coming from one of the two cables in the disabled outlet box. You can then test for voltage with a voltmeter, or non-contact tester to identify which one is the power source. If one or more of the other outlets still work, then you'll need to repeat this until you can pin down the power source.

One thing I would do before starting the above is to verify the circuit that each of the outlets is on. Otherwise it could get real confusing.

Also, I wouldn't do it the way you are going to do it. I would get a GFCI breaker instead. I have them in my house, and have never had a problem with one. And, just think, you won't have to spend time tracking down the first outlet in the run.

Good luck.

  • 3
    Breakers are the Right Answer here, yeah. "Combination" breakers are about $50 each, they do AFCI and GFCI, so cover you for all three kinds of arcing: to ground, between wires, and in series along the wire. Not sure they're appropriate for EVERY circuit, though: ask an expert! :D [Oh, and definitely don't install on a circuit that has life support equipment on. Keeping that running is usually considered more important than arc detection!] Commented May 18, 2021 at 0:02
  • If I install a GFCI/AFCI breaker into a panel for a circuit with outlets that are ungrounded, am I allowed by code to replace the 2 pronged ungrounded receptacles with normal receptacles, as long as I label them with the GFCI protected outlet sticker?
    – gcr
    Commented Jul 14, 2023 at 16:22

Use the ideal 61-164 circuit tester. By checking voltage drops. Sparky channel on YouTube has a great video on this. The outlet with the least voltage drop is the first on the run. Shut off all breakers except the one your working on look for outlet and lights with power. Mostly it’s the one closest to the panel. It could be anywhere. Good luck.

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I also have switched (bottom) outlets. For my guest bedroom, the electrician ran power from the panel to the first outlet in the chain using a 2-wire Romex (white, black and ground). This outlet is adjacent to and to the right of the entry door. This outlet has the 2-wire Romex from the panel and a 3-wire Romex (white, black, red and ground) that goes to the next outlet in the chain. All additional outlets have two 3-wire Romex cables entering them. The second 3-wire Romex in the last outlet in the chain leads to the outlet wall switch located adjacent and to and to the left of the entry door. So, the wiring is done in one big loop wrapping around the room starting and ending at the door. Now that I have replaced the first outlet in the string with GFCI, all of the outlets are now GFCI protected and all of the bottom outlets are still switched except for the first outlet in the chain. So, to find the first outlet in a chain, I would turn the power off to the room, look at where the switch for the switched outlets is and look at the outlet on the other side of the door. If the outlet has a 2-wire and a 3-wire, there is a good chance that you have found the first outlet in the chain. If the electrician ran 3-wire Romex to the first outlet (more expensive / wasteful) then this method is not as helpful. If the outlets are not switched, it still might be helpful to start next to the door with the first outlet in the chain being the one with easiest (closest) access to the panel.

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