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This is the wiring on the outlet. My current tester shows that the two white wires are neutrals, the red is hot, and the black ones that are twisted together with the black connector cap. The green ground screw is in the lower left corner and s not connected to anything.

This double outlet is connected to a switch. Both outlets depend on the switch. If the switch is on then both have power. If it's off the both don't.

The picture shows the wiring involved. The outlet is connected to one hot and two neutral wires. The other hot screw and the grounding screw both have nothing attached to them. My non-contact voltage tester shows that the two white wires are neutrals, the red is hot, and the black ones that are twisted together with the black wire nut are also hot. The green ground screw is in the lower left corner and is not connected to anything (old house).

Ultimately, the goal is to have this be a permanent hot outlet. Right now, though, I'm trying to figure out what is going on with the wiring.

By looking at the switch wiring (elsewhere on the wall) I was able to determine that the red wire is connected directly to that switch.

What else is going on here? Does the double neutral mean that the red wire is likely carrying 240V rather than 120V? Does the wire nut with the blacks mean that the whole thing is connected to another outlet or fixture somewhere else (even though the second hot screw is not being used)?

Update: I know that the ground is not attached in the outlet (or the switch for that matter). There exists no metal conduit piping for the wires to protect them on their way to the circuit box. Hence, even though the outlet (and switch) boxes are metal they can't be used for grounding. I've been informed that a feasible solution is to install GFCI breakers in the main box. It is probably not the greatest solution but should mitigate the problem without tearing apart the walls and structure of the house to rewire everything.

Here's a picture of the right side of the switch after I removed the electrical tape covering everything. Switch right side

Here's a picture of the left side of the switch. Switch left side

I know that adding all those black hot wires to the one terminal screw is considered the wrong thing to do. I didn't wire the house 70 years ago. And yes, I did re-cover everything with electrical tape after i put it all back together. I know it's not an ideal solution. It's worked ok so far and I didn't want to leave everything exposed while I asked my question.

The switch is one switch out of 4 in that one box. You can clearly see the red hot and the three black hots coming off of that switch. Of those four switches - one controls the overhead light, one controls the outside porch light, the one we are worried about controls the outlet inside the house, and I'm not sure about the fourth one.

I don't know what else is on the circuit controlled by the switch that controls the outlet.

Have I just (unintentionally) informed everyone that this project is significantly complicated/technical? Do I need to figure out the wiring of those other three switches before I commit to having anything done (by me or a professional)? What's the right next step here?

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    Can you post photos of the wiring at the switch in question please? Commented Sep 24, 2023 at 2:03
  • They upper switch terminal is rather hideous. I'd tolerate the loop-through, reluctantly, but not with the third wire present. That desperately needs to be redone as a pigtail, before that screw loosens, though the tape provides a (very) slight safety net... I think I'd need to see what else is happening in the outlet box, but, yeah, this is clearly an amateur job.
    – keshlam
    Commented Feb 23 at 15:39

3 Answers 3

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Does the double neutral mean that the red wire is likely carrying 240V rather than 120V?

No. Hot-to-neutral voltage does not normally vary without a transformer. It should be around 120 VAC at every point in the system. This can be measured easily with a multimeter. Any substantial increase would indicate abnormal resistance on the neutral path.

Does the wire nut with the blacks mean that the whole thing is connected to another outlet or fixture somewhere else?

It is either another outlet or it is part of the switch connection, depending on which direction the cables were run. For example, sometimes a light switch has the first box on a circuit.

What else is going on here?

The grounding connection appears to be missing for this receptacle.

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This is probably how things are currently set up (but seeing a picture of the switch box wiring would help confirm):

  1. At the switch box, power comes in from fuse or breaker box via "/2" cable (hot and neutral / black and white wires, possibly plus ground). Hot (black) goes to one switch terminal and also to hot (black) in outgoing "/3" cable (black/white/red). Incoming neutral (white) goes to outgoing neutral (white). Second switch terminal connects to red in outgoing cable.

  2. In the pictured receptacle box, the /3 cable comes in. The red (switched hot) wire goes to the hot side of the receptacle. The incoming neutral goes to the neutral side of the receptacle. An outgoing /2 cable proceeds on to provide un-switched power to other receptacles in the room. The joined neutral terminals of the receptacle are used in lieu of a wire nut to connect the outgoing neutral to the incoming neutral. The outgoing hot (black) is connected to the incoming un-switched hot (black).

If you want to make this receptacle always-hot there are a few options:

  1. Both halves always-on: remove the switch, wire-nut its two insulated wires together, replace the switch cover plate with a blank cover plate.
  2. Both halves always-on: Remove the red wire from the hot side of the receptacle, cover it with a wire nut, run a new short piece of wire from the wire nut with the two black wires to the hot side of the receptacle.
  3. Half always-on / half switched: break of the tab between the two screw terminals on the hot side of the receptacle, run a new short piece of wire from the wire nut with the two black wires to the hot side of the receptacle.

Remember that code requires at least one switched "outlet" (either light fixture or receptacle) in each room to be controlled by a switch at the doorway(s). If this is the only switched thing in the entire room, you may not make it 100% always-on, but making it half-switched would be fine.

You also need to fix the grounding of the receptacle. Since there appear to be ground (bare) wires in the back of this metal box, the receptacle's ground terminal should be connected to them. You can wire-nut one end of a short piece of bare (or green) wire to the ground wires in the box, and attach the other end to the receptacle ground terminal.

"Self-grounding" receptacles do exist for use in metal boxes, but you don't appear to have one of those, and would not be able to use one. They require firm contact between a grounding clip on the receptacle's mounting "ears" and the device screw flange on the metal box. Your box is recessed too far into the wall for that to happen.

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Here is one possible scenario (though comments have pointed out that neutral in a switch loop is a recent thing, and this stuff looks old):

  • One cable incoming: black hot/white neutral
  • One cable going to switch: black hot (the black hots are wire nutted together), white neutral (the whites are connected via the side of the duplex receptacle), red switched hot (from the switch to the line side of the duplex receptacle).

Another possible scenario, which actually ends up quite similar from a practical standpoint:

  • Power goes to switch box black hot/white neutral
  • Cable from switch box to receptacle box black hot/red switched hot/white neutral
  • Cable from receptacle box to next receptacle box black hot/white neutral

If this is indeed one of these configurations, it would be a little clearer if the neutral wires used a pigtail - incoming (or outgoing) + switch (which needs it for timer, smart switch, etc. and is required under current code but used to not be required) + receptacle. But using the receptacle as the connector is a little simpler/easier to actually do.

To turn this into an always on receptacle and keep power at the switch and/or the next receptacle:

  • Remove the wire nut from the black wire nut.
  • Add a short black wire (14 AWG or 12 AWG if 15A circuit, 12 AWG if 20A circuit) to the other two black wires and put on a wire nut (may need a new wire nut).
  • Disconnect the red wire and cap it with a wire nut.

Now you have an always on receptacle, and you still have black and white going to the switch (or next receptacle) to provide hot and neutral.

Note that most of the time a switched receptacle is there because code requires most rooms to have one of:

  • Always on light - not practical in ye olden times, but often quite practical in some locations thanks to LEDs.
  • Switched light fixture.
  • Switched receptacle that can be used with a plug-in lamp.

So removing the switch altogether (which is easy) will often violate code. In those cases, disabling the switched mode of the receptacle equally violates code. So the next step is usually to run a new cable from the switch to a wall or ceiling mounted light fixture.

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  • One downvote I understand...that seems to happen regularly. But 2? Anyone care to explain what I got so wrong here? Commented Sep 24, 2023 at 3:36
  • It is not even remotely plausible that this ancient wiring was set up as a switch loop with neutral. No, it's not impossible but it is definitely not likely.
    – nobody
    Commented Sep 24, 2023 at 16:28

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