I disconnected the wires in a working outlet in my house (built 2001) while replacing the termite damaged studs. I forgot to document the wiring and now I am having problem putting the wires back. There are 3 sets of cables in the outlet box. Cable A and B have white, black, and ground. Cable C has white, black, red, and ground. On the same wall, there are another outlet and a triple switch panel.

3 f'n cable outlet I tried to pigtail all the blacks together and put them into screw #3; all the whites pig tailed into screw #1; and red wire to screw #4. When I turned the power back on the circuit breaker tripped and I decided to stop and seek help! Thank you in advance for any suggestion.

  • On the sides of the duplex receptacle are the metal tabs that connect the two individual receptacles intact or have they been removed? Do you have a voltmeter? Jul 18, 2017 at 4:20
  • Is there only one duplex receptacle in this box? Do you remember if one or both of the receptacles was switched by one or more of the wall switches? Or was this receptacle always live. Jul 18, 2017 at 4:26
  • The metal tabs on both side are intact. Yes, I have a volt meter. There is only one duplex receptacle in this box. I do not remember if one or both of the receptacles was switched by one of the wall switches. However, I am certain that we only used 2 of the 3-switch panel to control 2 lights.
    – HuTieu
    Jul 18, 2017 at 4:57
  • Some of the experienced electricians on this site can use the info you have given in answer to my questions along with some voltages to tell you how to reconnect the wires. Jul 18, 2017 at 5:12
  • With the breaker switched on for cables A and B measure the voltage between each black (B) and its assoc W wires and record. For cable C measure voltage R to W, B to W and R to B and record. Do this for each switch position that could affect this receptacle or other receptacles. Jul 18, 2017 at 5:21

1 Answer 1


There are multiple combinations possible.

From what you have said so far here is what I am thinking:

Cable A or B is the hot feed from the main panel. The other cable, either A or B is the feed to the other receptacle. Cable C is the feed to the switches and the red wire is the switched hot wire returning from one of the switches.

It sounds like at least one receptacle in the room was switched for a floor lamp. It doesn't have to be split wired both plugs on the receptacle could be switched.

It could be the receptacle in your drawing or the other or both. The switched hot should be the red wire. If you connect the red wire to a receptacle you should not connect a black wire. Unless you are going to remove the connecting tab on the hot side of the receptacle and split wire the receptacle.

You should take some voltage readings to determine which cable is the hot feed from the panel. Then, with the circuit shut off, you can use the resistance or continuity setting of the meter to determine which cable goes where and which wire is which.

Good luck!

  • If your voltmeter leads have optional alligator clips, clip them to the two wires under test, then cycle the switches and see what the effect is on that voltage. You can do this without alligator clips, but it is a lot easier with them. You can also use the alligator clips to make resistance measurements with the breaker off. Jul 18, 2017 at 11:33
  • Thank you ArchonOSX! Will try that today when I get home.
    – HuTieu
    Jul 18, 2017 at 13:04
  • Following @ArchonOSX 's observation if you have the possibility of splitting the duplex receptacle so that only one receptacle is switched and the other is always powered, then this would be more useful. But figure out how to do this before you break off the tab on the hot side. If it turns out that you can't do this you would have to make a jumper to replace the tab or buy a new receptacle. If you have the good type of backwiring holes then you could use a pair of holes for a jumper should that be necessary. Jul 18, 2017 at 23:03

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