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I am replacing some outlets and switches in my home as most of them are old and discolored. When I pulled this one out it had 2 white and 1 red wire connected, and 2 black wires in the box which were not connected to the outlet. The old outlet only has 1 screw on either side, but my new outlet has 2 screws on each side. I know typically one side is for the white wires, the other side is for the black wires. I’m not sure how to proceed with wiring the new outlet.

For reference, I have read that some times the red wire is there to connect the outlet to a switch. The only switch in the room does also have a red wire in the box. I don’t know if that helps inform how I should wire the outlet. *editted to add: I checked to see if the outlet is switched. It is not. It is powered regardless of wether the light switch in the room is flipped on or off.

outlet with attached 2 white and 1 red wire and unattached 2 black wires
Click all images to embiggen

outlet with 2 white wires attached to 1 screw on right of outlet with 1 red wire attached to 1 screw on left of outlet

only light switch in room with 1 red and 1 black wire attached to switch

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**Key Question: Is this receptacle switched?

I hope the answer is yes. If it is not, then there is something strange going on.

Assuming it is switched - i.e., flip that switch on and the receptacle has power, off and no power:

  • Hot flows through the box using the blacks
  • Neutral flows through the box using the whites
  • Switched Hot comes from the switch on the red wire

That is totally normal. But what is not normal:

  • Duplex receptacles with only one screw on each side. That is technically OK but very unusual these days.
  • No ground pin! That was quite common 50 years ago. You definitely want to fix that. If you were planning to replace with ungrounded receptacles, return them.

The good news is that you almost definitely have ground. You have metal boxes. The only question is whether you have ground wires connected to the metal boxes. You can poke around and look for them - should be a bare copper wire coming out from each cable. Or you can use a multimeter to check for very low resistance between neutral (white) and the metal box. Assuming the boxes are grounded:

  • If you use a self-grounding receptacle, you just screw it in and done.
  • If you use a non-self-grounding receptacle, you need to connect a ground wire from the ground screw on the receptacle to the metal box with an appropriate screw.

In addition to a multimeter, I recommend a "Magic 8-ball" tester:

Klein tester

These don't give definitive answers to strange wiring problems. But for standard receptacle testing they work quite well, and are a good way to double-check your work when you think you are done installing a receptacle. If you see anything other than "CORRECT" then you know something is wrong (even if you may not know exactly what is wrong).

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    If you choose to use the "magic 8-ball" tester, there are recommendations to cover over the entire label leaving only the model number and the "Correct" row showing. Anything other that "Correct" means there's something wrong, but the lights aren't likely to tell you exactly what.
    – FreeMan
    Jan 7 at 18:06
  • @FreeMan Or rather, the lights can tell you what if you have a nominally normal setup and you understand what they really mean. Also, stay away from a "super fancy" tester - once it gets computerized that adds a number of reasons why the lights may be meaningless. Jan 7 at 18:20
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    Just channeling my inner Harper... :)
    – FreeMan
    Jan 7 at 18:25
  • I checked if the outlet is “switched”. It is not. The outlet works to power a light regardless of whether the switch is on or off.
    – Devin
    Jan 7 at 22:00
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    Metal boxes do not imply the presence of ground. Metal boxes have existed for a long time, including in the era before grounding conductors were required or standard. We can see in the photo that the cables present are very old cloth-covered ones, which are very unlikely to contain ground wires.
    – nobody
    Jan 8 at 0:08

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