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I recently bought a 1951 home. There is a switch in the living room that appears to have been intended to control one or more outlets in the room (the switch affects no lights and all lights are controlled by other switches). However, the switch does not affect the outlets either: whether the switch is on or off, all outlets are on.

The outlets are all wired with either two black and two white wires or one white and one black. There are no red wires like you'd see with a typical newer switch-to-outlet configurations. The switch, which is a new replacement, is wired with two black, and the two white are capped off together. The bottom black wire for the switch does receive electricity. But again, no red wire at the switch box.

Other than incorrect wiring, is there a possible explanation in an older home as to why the wires would be configured and would function this way? Is it possible that it is in fact correctly wired to operate outlets but the outlet being controlled would have to be installed a specific way (eg, removing the bridge between the two hot terminals)?

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Yes, most older houses were wired with half-switched outlets because they did not have switched overhead lights.

It's entirely possible that someone replaced the receptacles with new ones and did not break off the tabs between the 2 halves of the outlets, thus both top & bottom outlets are always live.

Using red insulated wire to go to the switched receptacle was a convenience, but I don't believe it was ever required by code, thus there's no reason for you to be concerned about the fact that there aren't any /3 cables leaving your switches. Actually, in 1951, most (all?) wiring would have been individual wires with cloth insulation, not the modern NM cables with multiple, individually insulated wires within a sheath, so it's even less surprising that you're not seeing a red wire.

The outlets with 2 pair (white/black) of wires are somewhere in the middle of the run - power comes in on one pair, provides power to this outlet, then carries power on to the next outlet in the string.

The outlets with 1 pair (white/black) of wires are at the end of the string. Power comes in and is provided to the outlet, but doesn't need to carry on to another outlet.

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  • Thank you! I wondered if that might be the case. Two questions. Is there in easy way to tell which receptacle needs to have the tab removed? I would have thought that when top and bottom of an outlet are always live (because tab is there) and the switch also routes power to the same outlet, then flipping the switch to ON would cause the breaker to trip, power trying to come to / leave the outlet in two directions on the same wires. Is that incorrect? Jan 19 at 21:11
  • The usual wiring for switching only one half of a duplex receptacle would not trip a breaker if the tab was incorrectly left intact. The always hot and the switched hot are normally on the same breaker and so are normally on the same leg. But it is not proper to feed power to a receptacle from two separate hots not in the same cable. Leave the switch in the off position until you sort this out. Get a non contact voltage tester. Jan 19 at 21:34
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    Since none of the receptacles are described as having 3 pairs or 4 pairs of wires, or even an extra black wire, there's no particular evidence in the provided information that indicates a reason to believe that any of the outlets are half-switched. If one of the outlets with 2 pairs of wires was also at the end of a run, AND had a switched wire to it, that could be the case - but it would be a snipe hunt to find it, and the switched wire may go someplace else entirely (cue that cartoon of the dog complaining about the light in his house going off and on randomly.)
    – Ecnerwal
    Jan 19 at 23:10
  • @Ecnerwal It appears that none of the outlets with 2 black, 2 white wires is at the end of the run. If that is correct, is there anything that could be going on here other than incorrect wiring? I mean, there's a black wire that is activated by the switch and it goes somewhere, but I can't figure out where it goes. Is there anything else I could look for or try? Jan 22 at 17:40
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    It's not "incorrect" - it's simply unknown. It may never have controlled switched outlets, or it might have, and been changed. It might control something you have not found, which may not be obvious - the outlet on the roof for the light-up santa and 8 reindeer...short of following the wire, there's no way to know.
    – Ecnerwal
    Jan 22 at 18:01

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