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I recently purchased a used park model home, located in USA, with stick built attachment. I have a light switch ,with current, that does not control any light or receptacle,that I can find, in or out side of the structure. The switch is in a two switch box. The box has 4 cables coming in. One cable has a red,black,white and ground wire. The red wire is attached to subject switch and has a black wire pigtail connected to the incoming black wires. The other switch has 2 black wires. One is an incoming wire and the other is a pigtail connected to the incoming black wires. The white wires are all tied together. What I overlooking? I appreciate any advice.

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  • Hello, and welcome to Home Improvement. Would you add a picture of the interior of the box, with the switches pulled out (but still connected)? Thanks.
    – Daniel Griscom
    Apr 19, 2019 at 21:14
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    Have you checked that none of your outlets are half-switched? Sometimes, the tab connecting the top and bottom of a duplex receptacle is broken off, allowing one half to be always-hot and the other half to be switched. It's possible that the 4-wire cable you describe goes to one outlet, with the black (always hot) and red (switched hot) connected to the top and bottom, both sharing the same neutral and ground.
    – Nate S.
    Apr 19, 2019 at 21:35
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    Moreover, if the half-switched outlet was replaced at any point and the tab was NOT broken on the new replacement, then both halves would be always-hot and the switch would still be powered but do nothing, as you observe.
    – Nate S.
    Apr 19, 2019 at 21:38
  • Can you post photos of the inside of the box? Also, which switch appears to control nothing?
    – ThreePhaseEel
    Apr 19, 2019 at 23:57
  • Thanks to all. Nate was right on the money. I removed tab and switch worked receptacle with red wire connection. Black wire connected receptacle was hot at all times.
    – JimR
    Apr 20, 2019 at 18:11

2 Answers 2

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You most likely have a split (or formerly split) duplex receptacle somewhere.

Most of the time, duplex receptacles are set up such that the top and bottom halves function identically and are fed by the same wire. However, by breaking a small brass tab on the receptacle, it's possible to wire them such that the top and bottom halves function separately. This can be done to allow one half to be always-hot, and the other half to be controlled by a switch, which I suspect is how your outlet was set up originally.

Duplex Receptacle Tab Connector

Now, if you've checked both halves of all receptacles in the room with the switch and find that they're all always hot, it's time to start pulling off some outlet covers. If at some point in the past the half-switched outlet was replaced, it's very possible that whoever replaced it just landed all the wires on the same screws as before, but didn't realize they also needed to break off the brass tab. This would result in the always-hot and the switched-hot wires being paralleled, and both halves of the outlet would be always-hot regardless of switch position. The fix for this, assuming you want the outlet to be half-switched again, is to shut off the circuit at the breaker panel, and break the tab connecting the two halves.

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  • Quite common for a switched receptacle.
    – Ed Beal
    Jan 20, 2021 at 19:58
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That's not unusual. The four cables are:

  • Always-hot and neutral from supply
  • Always-hot and neutral onward to next point-of-use
  • Switched-hot and neutral to one of the lamps
  • Always-hot, switched-hot and neutral to the other lamp, and from there, onward to the next point-of-use.

In the last case, the lamp uses switched-hot and neutral, and the onward power from there uses always-hot and neutral.

Color coding is extremely unreliable in home wiring because you are stuck with the standard colors that cables are manufactured in. However, in this case, by dumb luck, the color codes are consistent:

  • White is neutral
  • Red is switched-hot to one lamp
  • Black is always-hot in all cases
  • except for one of the two lamp branches, where the switched-hot is black
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  • Thanks to all. Nate was right on the money. I removed tab and switch worked receptacle with red wire connection. Black wire connected receptacle was hot at all times. – JimR 51 mins ago
    – JimR
    Apr 20, 2019 at 19:04

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