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I took out my kitchen and took some photos of the "old" kitchen's garbage disposal wiring:

enter image description here

As you can see, it has 2 black lines connected but only one white line connected, while one is capped off.

I know the main purpose is to use the switch to control one of the outlets BUT isn't this is the right way to wire it?

Ref: https://dengarden.com/home-improvement/home-wiring-guide-how-to-wire-a-switched-half-hot-outlet

I am a bit confused about the two setups and differences.

The thing is I tried to follow the diagram above and couldn't get the switch to control the outlet and it was ALWAYS ON.

Help?

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    Which cable comes from supply, and which cable goes to the switch? – Harper Nov 2 '18 at 6:16
  • That is a good question as I forgot to keep the record. I believe the top outlet is to garbage disposal. But regardless, I tried to repeat the same configuration and couldn't get the switch to turn on/off the top or bottom outlet... – HP. Nov 2 '18 at 7:23
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    Wait, doesn't the garbage disposal plug in to a socket?? I would expect one cable to go to supply and the other to the switch. – Harper Nov 2 '18 at 8:16
  • Did you change outlets? If so did you break the tab on the new outlet? – Tyson Nov 2 '18 at 11:04
  • not quite what you are asking but all the bare wires should all be pigtailed together and connected to the grounding screw in the box. – ratchet freak Nov 2 '18 at 14:34
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There's not quite enough information here to answer your question. But we can try after making a couple assumptions.

From what I gather the picture is of the outlet box and the garbage disposal plugs into the top outlet. Presumably the cable exiting at the top of this box is from the supply (or else the disposal would never run). The rest of your question implies that there is a switch box as well so I assume the cable exiting to the right leads to a 2-pole switch? You're trying to understand how to wire this switch such that the top outlet in the outlet box can be switched.

If my understanding of your question is correct then the switch is on a switch loop and the diagram you have posted does not apply. Instead wire as follows. Connect supply black to switch loop black. Re-identify the switch loop white cable as black and connect it to upper outlet hot. Leave the supply white connected to neutral outlet. With the hot tab jumper in place this will get you a switched outlet (both receptacles).

If you wish to switch only the top receptacle break the hot tab on the receptacle and connect supply black to the bottom hot side of the outlet. Use a pigtail since supply black is now feeding the switch loop and the lower receptacle.

  • My surmise is the the cable coming into the box on lower right is from the switch and the conductors are not a switch loop but rather the black is the switched hot and the white is its companion neutral. The cable coming in from the top is an always hot black and its companion white neutral. However the OP should be able to verify this with a voltmeter or non-contact voltage tester. If this is correct, then connect the capped off white to the neutral side of the same receptacle as its companion black and break the tab on the neutral side. – Jim Stewart Nov 3 '18 at 1:59
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You don't have a 3-wire cable; you have two independent 2-wire cables. To have two independent receptacles of the duplex receptacle with two 2-wire cables both tabs need to be broken off, so the neutral side must be broken as well. The hot and the neutral wires connected to a given receptacle must be in the same cable.

If the switch does not control one of the hot conductors at the receptacle, then the switch may be faulty or more likely wired wrong. Look in the box for the switch and see how the switch is wired.

EDIT The currently capped white neutral must be connected to the neutral side of the receptacle that it's companion hot is connected to. Break off the neutral tab if it is not already broken.

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    Only the hot tab needs to be broken. – Ed Beal Nov 2 '18 at 12:15
  • @Ed Beal, isn't it the case that if there are two separate hot wires (one switched) which are in two separate cables, then the neutral for each hot must be kept separate at the receptacle? The currently capped white neutral must be connected to the neutral side of the receptacle that it's hot is connected to and the neutral tab broken. Otherwise the currents in each cable would not be the same in the hot and the neutral conductors. – Jim Stewart Nov 2 '18 at 13:00
  • These are not 2 separate hots they are the same circuit so the neutral jumper can stay. Look at the drawing it is just pigtailed one to the switch and one to the outlet. – Ed Beal Nov 2 '18 at 14:59
  • I won't endlessly keep on with something with people who overall know 100x what I do, but I'll give it one more go. It doesn't matter that the line hots in the two cables are on the same circuit; both tabs must be broken and separate neutrals connected. The reason is that there would be unbalanced a/c current in one or both cables giving rise to induced currents and heating in any metal orifice or tube that the cable goes through. – Jim Stewart Nov 2 '18 at 17:06
  • Jim the schematic shows the splice at the box location and only 1 neutral coming in and only 1 hot. only 1 neutral is required to the outlet the OCPD is protecting this line and it could be a gfci breaker and it would not have any problem with this wiring. As far as the second white wire we do not even know where that comes from, there will be no heating issues at all the wiring is all in the same box. – Ed Beal Nov 2 '18 at 18:08

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