How to wire half-switched outlet with two black and two white

Question

I had done pretty well rewiring a number of normal outlets in my house. However, I managed to mess up the first switched outlet I tried to do.

The box had one wire coming in on the left (same side as the switch in the room), with one black and one white wire. Another went out the right side of the box, also with one white and one black. The box itself was grounded as all the others had been.

I noticed when I first opened the receptacle that one brass terminal had a white and a black on it. I believe it was the bottom one. There was a single white wire going to the silver terminals. The top outlet was controlled by the switch.

The problem is I dont recall which was paired with which. I havent been able to find a wiring diagram which matches what I have. Can someone walk me through how to put this back together?

Edit: so the answer was what we needed. However it turned out when we flipped the switch the first time with incorrect wiring we broke something in the ancient switch. A quick trip to Walmart later and we now have a working circuit.

Thank you so much!

Answer 1

It sounds like you're looking to end up with something like this

Notice the white wire that's been repurposed, is marked at both ends with black tape/marker/paint. And that the tab between the top and bottom receptacles, is broken on the "hot" side of the device. Also notice that a pigtail is used, instead of connecting more than one wire to a terminal on the receptacle.

To determine which set of wires goes to the switch...

1. Turn off the breaker, and make sure power is off.
2. Set your multimeter or ohmmeter to test continuity or low resistance.
3. Disconnect all the wires from the switch.
4. Test between the black and white wire of cable 1.
5. Test between the black and white wire of cable 2.
6. Toggle the switch.
7. Test the wires again

One pair of wires should test positive for continuity, when the switch is in the on position. This is the cable going to the switch.

NOTE: This type of installation is no longer code compliant (NEC), because it does not provide a grounded (neutral) conductor at the switch location.

NOTE: Grounding conductors have been omitted from the diagram for simplicity. Make sure all grounding conductors are properly installed.

Answer 2

The tab ( a little piece of metal that connects the two brass screws) on the hot side of the receptacle should be broke out of the new receptacle. (I assume when you say re-wiring you mean replacing receptacles. Then one brass screw gets an always hot wire (usually black) and the other brass screw gets the wire from the switch (could be black or red).

If you failed to remove the little tab then the receptacle will be hot all the time on both plugs and the switch will have no effect.

If the switch is wired incorrectly they might have taken the black wire to the switch and the white coming back from the switch (it is supposed to be the other way around to prevent this problem) and then they may have failed to re-identify the white wire with some black tape. So, now you have a white wire coming from a switch that is really a hot wire. People then mistakenly connect that white wire to the other white wires that are neutrals and when you flip the switch and it trips the breaker.

Good luck!