I just bought a TP-Link Kasa light switch (the HS200 single pole to be exact). It has two black wires, a white, and a green. The switch I want to replace has only black and red. Inside the box, I see there are white and green available. Can I do this? If so, please tell me how, or guide me towards where I can find the information. Really appreciate the help.

My proposed switch location

  • I brightened up the interior of the box so it can be seen more easily. Aug 10, 2021 at 7:01
  • Thanks, my answer should be similar to the instructions you got with the unit. Be sure to take pictures of the wiring so you can put it back if something does not work.
    – Gil
    Aug 10, 2021 at 7:06
  • 2
    1) Smart switches like this don't work well in metal boxes like the one you have there, and the TP-Link instructions say not to do it. If it does work it might work poorly or intermittently. I have had both success and failure doing this, and it's impossible to predict. 2) Does the old switch have three wires connected to it, all of them either black or red? Or does it have one black and one red? Is there another switch in your home that also controls the same lights?
    – jay613
    Aug 10, 2021 at 12:08
  • Can you post a photo that shows the inside of the box more clearly please? Aug 11, 2021 at 4:11
  • In addition to the metal box issue I wonder if the Kasa will fit in that box? Have you checked? Regardless of the wiring ... is there room in the box ?
    – jay613
    Aug 11, 2021 at 16:55

1 Answer 1


Did you read the instructions that came with it. Here is my best guess on how to wire it, I do not have one so I can only look at sketches. A. Turn off the breaker B. Take pictures in case you have to put it back. C. Remove the plate and switch. D. Connect each of the two black wires from the switch to the live wires probably black E. Connect the Green wire to the ground line (bare or green wire) F. Connect the White wire to the neutral (white wire) G. Mount the new switch in the box H. Put the Wall plate on I. Turn the breaker on. J. You should be ready to go

  • 1
    Read the question. "The switch I want to replace has only black and red." Yet you say "D. Connect each of the two black wires from the switch to the live wires probably black "
    – Ecnerwal
    Aug 10, 2021 at 10:50
  • You also stated " I see there are white and green available" you need those to make the switch work, what did the directions tell you? There are two black wires connect one to the red the other to the black.
    – Gil
    Aug 11, 2021 at 1:02

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