[Rav]

Sorry this is so long but I didn't know what info was critical or not to your understanding of what I'm dealing with here.

I've been replacing non-GFCI receptacles in my basement with tamper-resistant GFCI receptacles. So far I've done three. Two had no load to wire up, and one did. I had no issues with any of them and they're all working great.

Now I want to do the one in my garage (pics attached). Unfortunately this one is cabled in a way that the GFCI instructions don't cover, so I need some assistance with that.

The box has two cables, a line and a load. I verified that the line cable is supplying current to the receptacle, and the load cable isn't. I verified that there are receptacles upstairs that the load cable is feeding.

Both the line and the load cables neutral wires are connected as they should be to neutral screws on the receptacle. I verified that neither wire is carrying any current.

The load hot wire (black) is connected as it should be to one hot screw on the receptacle.

Here's what I'm uncertain about in terms of how to wire the GFCI:
The line cable has TWO hot wires (black and red). Both of them are connected TOGETHER to the second hot screw on the receptacle. After disconnecting them both from the receptacle, I verified that both of them are carrying current. Further, with the power off and still disconnected, I checked with a continuity tester and they have continuity with each other. What function are the two hot wires in this cable for?

I'm "just" a DIYer, but I found some issues with the existing wiring that I think need to be corrected, whether I end up installing a GFCI or not:

• The box isn't grounded

• The ground of the load cable is just hanging, not connected at all

• The neutral of the load cable is backstabbed instead of being side wired

• There are two wires (line black and red) connected to the same hot terminal, and one of them is barely hanging by a thread on to the screw. They should have been wire nutted together and then pigtailed to the screw.

Assuming I take care of all those issues, then I THINK this is how the GFCI should be wired, but I would appreciate it if people here would verify this:

1. The line cables neutral wire should be connected to the GFCI line "white" terminal (as per GFCI instructions).

2. The line cables black wire should be connected to the GFCI line hot terminal (as per GFCI instructions).

3. The load cables neutral wire should be connected to the GFCI load "white" terminal (as per GFCI instructions).

4. The load cables black wire should be connected to the GFCI load hot terminal (as per GFCI instructions).

5. The line cables red wire should ALSO be connected to the GFCI line hot terminal. There are two back-wire (not back-stabbed) slots, for the same line hot terminal, so one will be for the black and one for the red. THIS IS WHAT I AM MOST UNCERTAIN ABOUT, SINCE A SECOND HOT WIRE FROM THE LINE CABLE ISN'T COVERED IN THE GFCI INSTRUCTIONS.

6. Grounding: Wirenut together these four wires:

• A pigtail from the GFCI ground screw

• A pigtail from the box ground screw

• The ground wire from the line cable

• The ground wire from the load cable (currently not connected at all; it's very short, so I'll have to wire nut on an extension pigtail to that to make it longer)

I hope this all makes sense! Thank you for your help!

/ Rav

PS: See post #3 from me below for additional info (yes, there's more).

 

[Arrow3030]

My first thought is that this was at one time a switched receptacle. That's a bit odd to me in a basement but it's just a thought. Inspect a nearby switch box to see if there is a red and black connected. If I'm right, you'll want to disconnect the black and red at the switch box and the receptacle box to eliminate a series parallel circuit. Then you'll have an unused conductor between the switch and receptacle and everything should be straight forward from there.

 

[Rav]

My first thought is that this was at one time a switched receptacle. That's a bit odd to me in a basement but it's just a thought. Inspect a nearby switch box to see if there is a red and black connected. If I'm right, you'll want to disconnect the black and red at the switch box and the receptacle box to eliminate a series parallel circuit. Then you'll have an unused conductor between the switch and receptacle and everything should be straight forward from there.

Shoot, that reminds me of something I should have mentioned. There used to also be a toggle switch (i.e. for a light) in the box, but it was removed because it wasn't connected. Perhaps it had been connected at one time. Could the red wire have been for that? If so, when they disconnected it from the switch, why would they have had to add it to the receptacle along with the black hot? My wife now tells me that many years ago "they" had a hard time wiring up that box correctly. She doesn't know what the issue was. Anyway, there are no other switch boxes in the garage. And I have no idea where the line cable comes from as it just disappears into a wall.

Are you saying that when I hook up the GFCI, I should leave the red wire in that box disconnected and capped off?

 

[Jim Port]

The red may have been a switched hot with the constant hot black. Find the other end of the red.

 

[Rav]

The red may have been a switched hot with the constant hot black. Find the other end of the red.

Hi, Jim. I've looked and looked, and don't know how to find the other end of the red wire (where its cable comes from). Any suggestions on how to find it? We have two locations in the house (at the top and bottom of stairways) where two switches control the same light (which I assume is where an additional red wire would be used), but they have nothing to do with this location in the basement. Of course the red wire in question is coming from somewhere, but I don't know how to find where.

Did you see my second post in this thread (post #3) where I found that there used to also be a toggle switch in the same box as the receptacle, but that it was disconnected at some point (or perhaps never connected in the first place) and then removed? Could that have been the switch you're referring to?

I find it odd that when both the black and red hot wires are connected to the one hot terminal on the existing receptacle, that since both wires are live, that the receptacle works fine. And, if I temporarily disconnect the red wire just leaving the black wire connected, the outlet continues to work the same. Not only that, but with the red wire disconnected I checked every single receptacle and switch in the house that's on the same circuit (two years ago I mapped all the circuits to all the outlets in the house), and they were all working properly. Even though it's live, the red wire doesn't seem to make any difference, whether it's connected at the receptacle or not.

So, since I can't find the other end of the red wire, is it safe just to leave it capped off in the receptacle? If not, then I'll put it back the way I found it, connected together with the black wire to the receptacle. And can I change the receptacle to GFCI that way (with both red and black connected to the hot load)? Thanks.

 

[Arrow3030]

I'd leave the red wire off and capped.

 

[Rav]

I'd still like to understand why things are acting the way they are. It seems like it makes no difference whether just the black wire is connected, or if both the black and red are connected together, and I don't understand why that would be since they are both hot. Shouldn't it make some sort of difference? Is there something I can measure with a multimeter to explain what's happening? Thanks.

 

[kreemoweet]

Leave the red wire capped off and disconnected. There is no conceivable situation that would make it's presence on the receptacle anything other than the product of someone's earlier confusion and ignorance. There is really nothing to explain about the behavior you see: the other end of the red wire is connected (somewhere) to a hot supply from the circuit in question. You could have twenty such wires connected, and it would not change the behavior of the receptacle one bit. Maybe someday you will find the other end of the red wire and be able to deduce something.

Otherwise, your plan for connecting the GFCI and grounds is A-OK. I would recommend stripping off all that unnecessary cable sheathing in the box, as it will make working with the wires much easier. Only 1/4 in. of sheathing is required.

Also, you should be more careful with your nomenclature, as you seem to confuse the concepts of "voltage" and "current". A wire can be "hot" and have "voltage", without carrying any current. A disconnected wire most certainly does not carry current, no matter how "hot" it is.

 

[Rav]

Leave the red wire capped off and disconnected. There is no conceivable situation that would make it's presence on the receptacle anything other than the product of someone's earlier confusion and ignorance. There is really nothing to explain about the behavior you see: the other end of the red wire is connected (somewhere) to a hot supply from the circuit in question. You could have twenty such wires connected, and it would not change the behavior of the receptacle one bit. Maybe someday you will find the other end of the red wire and be able to deduce something.

Otherwise, your plan for connecting the GFCI and grounds is A-OK. I would recommend stripping off all that unnecessary cable sheathing in the box, as it will make working with the wires much easier. Only 1/4 in. of sheathing is required.

Also, you should be more careful with your nomenclature, as you seem to confuse the concepts of "voltage" and "current". A wire can be "hot" and have "voltage", without carrying any current. A disconnected wire most certainly does not carry current, no matter how "hot" it is.

Thanks, and thanks for your specific recommendations. If I understand correctly, it's almost as if one thick wire coming from a source was split into two thinner wires -- since they're still coming from the same source, it's the same thing. Hope I got that right.

You're absolutely right that I shouldn't have used "current" the way I did (such as "I verified that the line cable is supplying current to the receptacle"). I should have said that I verified which disconnected cable was line and which was load by determining which was hot and which was not.

 

[zolakk]

I would just check the boxes of everything that's not working when you have the circuit off, one of them will be the feed to this one and you'll probably want to know everything that's on the circuit for future use anyway

 

[TimPa]

look in the back of the box, do the red and black wires share the same sheathing? you said a "switch" was removed. it was possibly a three way switch, which often use a red and a black. is there another existing switch in the room that controls a light? if so, check in that switch box for the other end of the red wire.

make sure power is removed for ohm checks.

also realize that if you connect the "load" wires to the load terminals on a gfci, that whatever device is connected to those wires is also protected by that gfci. however, if you connect the "load" wires in the box to the "supply" (incoming) wires to the box, the load is then independent of the gfci.

 

[Rav]

look in the back of the box, do the red and black wires share the same sheathing? you said a "switch" was removed. it was possibly a three way switch, which often use a red and a black. is there another existing switch in the room that controls a light? if so, check in that switch box for the other end of the red wire.

make sure power is removed for ohm checks.

also realize that if you connect the "load" wires to the load terminals on a gfci, that whatever device is connected to those wires is also protected by that gfci. however, if you connect the "load" wires in the box to the "supply" (incoming) wires to the box, the load is then independent of the gfci.

Thanks. Yes, they're in the same cable. I've already installed the GFCI, and left the red wire disconnected and capped off. From her memory of what was done at that receptacle two decades ago, my wife now remembers that the person doing the electrical work was trying to install a switch there that would turn the overhead light on in the garage when we came in one door from outside, AND pair it with a switch in the basement once you come in another door from the garage so that either switch would turn it on or off. But for whatever reason they were unable to make it work (my wife says the wrong things turned on and off), so they abandoned the effort. That, apparently, is what the red wire was for. But I looked in the box where the toggle switch is in the basement, and there was no red wire there. In fact, what was there was old armored cable wiring. So it's still a mystery where the other end of the red wire is.

Everything on that entire circuit is working, including the one outlet that is downstream of the GFCI and fed off the GFCI load terminals (and it trips the GFCI when I press the GFCI test button on an outlet tester plugged into it).

I appreciate your, and everyone elses, help! Thank you.