I started to install my KASA smart switch but when I opened the unit I wasn't able to find a ground wire. I currently have two black wires (one stabbed into the switch and the other is wrapped around the bottom screw on right side). I have a few questions:

  1. Is the top black wire a hot wire or a ground wire? This seems to be going to the same area as the neutral. If this is a black hotwire, this would go into the black KASA wire.

  2. The bottom black wire actually hooks around and then connects to another light switch to the right. Do I leave this wire as is and surround the nut around this wire with the KASA wire?

  3. I read a grounded wire is not needed if your switch is plastic. Is this correct? The junction box is metal...

UPDATE: okay, I looked harder and saw that there is a copper wire attached to a screw that the back of the junction box (and is cut with no extra copper wire). Does this mean that the box is grounded and the switches are grounded as they are connected to the box?

UPDATE 2: Please see image 3 onward for updated photos with the copper cut at the back of the junction box. You can see that the hot wire and neutral wire come out of the same area. The copper wire is attached to a screw.

When looking at the bottom of the switch, I see that there is a copper (i think it is) attached to the screw, which touches the metal junction box.

Is this how the switch is grounded?

Please see images:

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  • Can you post a photo that looks into the back of the box? Nov 28, 2018 at 0:15
  • #3 is backwards. Only if it's made out of metal, run in EMT, and in a metal box can you forgo the ground wire. If those switches have a UL listing on them I will crap my pants...
    – Mazura
    Nov 28, 2018 at 1:59
  • @Mazura -- if the switch face, yoke, and faceplate are plastic and non-substitutable, then Ex. 2 to 404.9(B) kicks in which allows the omission of a ground wire to the switch. (Think "double insulated light switch", and you'll get the idea :) Nov 28, 2018 at 4:35
  • What is 404.9(B) Ex. 2? Sorry, i'm not familiar with that. Also, question about the black wire on the bottom right being connected to the switch to the right. Do I bend that and put it in the wire fastener with the KASA black wire?
    – LNG
    Nov 28, 2018 at 4:54
  • 404.9.b ex 2 would be a code reference from the National electric code. Saying if plastic the ground is not required.
    – Ed Beal
    Nov 28, 2018 at 15:36

1 Answer 1


Edit: switches (not receptacles) are allowed to make a ground connection via the mounting screws, even if the switch body doesn't rest hard against the metal junction box. So that solves that.

Ground wires are always green, green/yellow, or bare copper, except in old installations in Russia. Ground wires usually go onto green screws. Use of stab connections for grounds is prohibited because of their unreliability.

  • Actually, the flush-to-the-box rule only is for receptacles it turns out -- 250.146 only governs receptacles, while 404.9(B) governs switches and allows the screws to be part of the grounding path. Nov 28, 2018 at 0:47
  • Ok, I checked again and at the very bottom of the switches there are these green screws but there is no copper connected to it. At the back of the junction box, there is a copper wire that comes out where the neutral wire is but it only is connected to a screw. I will take a picture of it tomorrow with more lighting.
    – LNG
    Nov 28, 2018 at 3:44
  • Thanks for your help Harper! Does that mean i'm good with the ground wire just connecting to the junction box? How is it grounded if my switches are plastic? I will take another picture tomorrow of the inside of the box too.
    – LNG
    Nov 28, 2018 at 5:00
  • If you want to be sure you can pigtail the ground and properly connect it around. Nov 28, 2018 at 9:05
  • Have updated with images! Also, found that there is copper (i think it is copper) at the bottom of the switch that is connected to a green screw. This is then connected to the junction box.
    – LNG
    Nov 28, 2018 at 19:38

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