Previous owner replaced all switched outlets and made them always hot. How can I figure out which switches used to control which outlets?

Is there any trick to figuring this out? Currently my best reasoned method is verifying the switch is connected, removing all the receptacles and testing for no voltage on all hot wires with the switch off. Literally every room in the house but the dining room has one "do nothing" switch. I have checked for half hots.

All rooms having working overhead lights on switches. Two rooms have unused fan switches as the fan/light fixtures are remote controlled.

  • Main reason by code for switched outlets is to turn on/off desk/floor lamps if the room does not have ceiling lights. This might be a legal problem of previous owner if ceiling lights not installed. All rooms must have light/s controlled by a switch near doorways/entrance ways.
    – crip659
    Commented Sep 20, 2022 at 0:12
  • All lights work on switches. There are two rooms with unused fan switches, do to remote controlled fans. The 3rd switches are almost certainly for receptacles.
    – Andrew V.
    Commented Sep 20, 2022 at 0:18
  • I'm curious as to why you need to know this. If a switch doesn't do anything, isn't that your clue that this switch was controlling a switched outlet? If the outlets are no longer switched and don't need to be (because of switched overhead lighting), does it matter which one(s) used to be switched? I'm sure you have reasons, I'm just curious what they are because I'm not seeing it.
    – FreeMan
    Commented Sep 20, 2022 at 14:27
  • While our legal requirements are certainly met, we'd like to control certain lamps through a switch for the sake of mood lighting. Occasionally we will need light, but don't want the excessive brightness of the ceiling lights. There's also a glare issue in one room with the over heads.
    – Andrew V.
    Commented Sep 21, 2022 at 12:45

1 Answer 1


It's best you redo the work, because people who don't know about breaking off tabs is absolutely certain to not know about the NEC 110.14 torque screwdriver requirement (sloppily torqued screws are now understood to cause many overheat or arcing problems).

The first spotter's guide is unusual wires. If you have the standard /2 black+white in, and /2 black+white out, that's probably not a split/half-switched receptacle.

However if red wires are in play, or if one of the black/white's is reversed (white with the always-hots, black to a receptacle terminal) -- that is a likely location of a split receptacle.

Usually these people are replacing the receptacles for aesthetics' sake, and don't know a thing about wiring. So they carefully move each wire from exactly the place it was on the old receptacle, to exactly the place it is on the new receptacle. So hopefully the information you need will be preserved.

  • 1
    I'm hoping he was kind enough to connect things exactly as they were. His wiring elsewhere in the home has been sloppy at best and dangerous / illegal at worse. I'm not an electrician but I know how to read code, ask questions and research what I want to do before I do it. Thanks for your answer.
    – Andrew V.
    Commented Sep 20, 2022 at 0:37

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