I am trying to replace an outlet, but am having trouble figuring out how to wire it properly. The top receptacle on the outlet is supposed to be connected to a switch. When the switch is turned on the 2 blacks test hot, as well as one of the neutrals. When the switch is off, the neutral and 1 black test hot. How do I wire this properly?

Where I am at: I broke the tab between the poles on hot side of the outlet, just like the old outlet. I also see that the pigtailed black line goes to the lower receptacle, which is always on. I think the black line that is controlled by the switch goes on the upper hot side of the line. But is it okay to have the hot neutral on the other poles?

wiring diagram

  • 3W->4W 120V
  • 1B->4W 120V
  • 2B->4W 30V when the switch is in the off position, 120V when it's in the on position
  • 3W->2B 60V

My multimeter may not be that good. It's new, but the voltages jump and I often feel like I am getting different readings.

1B & 3W are always carrying power, 4W is neutral, 2B is responsive to the switch. There are 3 sets of wires entering the box.

Updated picture

enter image description here

1 is carrying power, 3 goes on to the remaining outlets, and 2 runs to the switch.

  • What do you mean "test hot" -- how are you testing? Neutral to ground should be 0V, hot to ground and hot to neutral should be ~120V. If you are seeing different (such as non-zero voltage on neutral to ground) then something is wrong.
    – gregmac
    Commented Mar 13, 2015 at 19:15
  • I am using a non-contact voltage tester. 2 of the wires always show voltage (1 black, 1 white), 1 additional wire (black) shows voltage when the switch is in the "on" position. The last white wire has no voltage.
    – Mark C
    Commented Mar 13, 2015 at 19:17
  • Non-contact is great tool for general use, such as verifying a wire is not live before you cut or work near it, finding the breaker for a circuit, etc. I always have one in my tool bag if not my pocket when doing any type of reno work. However, they're not appropriate for actually doing electrical diagnostics, because they too easily give false readings. You should really get a multimeter for testing actual voltage, and at this point, knowing the voltages is the only way to help you out.
    – gregmac
    Commented Mar 13, 2015 at 19:24
  • See edits for voltage measurements.
    – Mark C
    Commented Mar 13, 2015 at 19:57
  • 1
    Can you post some labeled photos of the wiring? Don't forget, the color of a wire's insulation does not always indicate its function.
    – Tester101
    Commented Mar 13, 2015 at 19:57

2 Answers 2


Based on your readings, the 1 side black, 2 side white(! retag this wire with black electrical tape!) and 3 side black should be nutted together and pigtailed, and the 1 side white should be pigtailed to the 3 side white apparently -- there looks to be some sort of load plugged into the outlets connected to the 3 wires, which'd explain why the 3 side white reads 120VAC with regard to the 1 side white. From there, you can then connect the white pigtail to the silver screw, the black pigtail to the lower brass screw, the 2 side black to the upper brass screw, and the bare pigtail to the ground screw.

The funny voltage readings on 2B with the switch off are due to the high impedance of your meter seeing capacitive coupling of a small amount of energy into the switched-off wiring.

  • I broke the pigtail and 3W is no longer hot. This means it should be coming back from the switch, or from the remainder of outlets on the circuit? 3W was on the 2nd neutral pole I believe.
    – Mark C
    Commented Mar 13, 2015 at 22:45
  • I added a second picture, which should be more useful. As far as I can tell, 1B brings in power, is pigtailed to 2W & 3B. 3B goes on to the remainder of the outlets on the circuit, 2W brings power to the switch. 2B brings power back down to upper receptacle on the outlet, 1W is neutral, and I am not sure what 3W does, but it was hot under the previous configuration (3W)
    – Mark C
    Commented Mar 13, 2015 at 23:17

the 2 black wires are common line you can call it line 1 the other black is the line 2 you can test it with the lihgt tester only if you test the common line with the light tester it may light but half light only you can see the difference after you test both.the other goes the same with the 3white the two whites has 0v it is the common to the 2 3w switches the other white is either line 1 or 2 common to the other black wire only different collor because it goes to the lights and the black goes to switch and outlets make sure to get the line 1 and line 2 first and mark it then the 2 common for the 3w

  • 1
    This answer needs some formatting, It doesn't look like there's any punctuation in there at all.
    – Tester101
    Commented Dec 17, 2015 at 14:51

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