Computers & Electronics

Help installing kasa switch

  • Last Updated:
  • Sep 19th, 2021 3:31 am
Nov 10, 2019
429 posts

Help installing kasa switch

Not sure which wire is which in this case with double switches next to each other. Trying to install Kasa switch for the left one on the pic. Inside there's a bundled unused white wires. Haven't uninstalled any switches off yet

Any help appreciated!
  • IMG_20210918_140834.jpg
  • IMG_20210918_140818.jpg
5 replies
Deal Addict
Apr 13, 2005
1511 posts
Markham, ON
If you don't know what you're looking at, perhaps an electrician would be the best idea.

Whites are neutral, red & black are hot wires.
I couldn't see it in the pictures, but there's probably a bare copper ground wire.

Typically, if there's a red, there's like a 3-way switch.
Sr. Member
Aug 31, 2012
634 posts
I ended up hiring an electrician to install mine. Plus wanted to split/change some switches so it was beneficial to do it all.
Deal Fanatic
User avatar
Aug 16, 2010
6851 posts
Hmm, looks like the left switch is a 3-way switch which means you probably have a pair 3-way Kasa's (HS-210) to replace it with? I'll take a shot at it.

Assuming this is the first 3-way switch in a switch>switch>light configuration, I would wire this switch like this:
  • The black wire with the bare part hooked around the bottom right terminal (and contining to the other switch) would be the common wire providing live current from the fuse box. You need to connect this to the line the line/load wire in the Kasa with a wire nut. Then use another length of black wire between this wire nut and the other switch so that this black wire continues to provide power to the other device.
  • The other two black wires on the left switch (upper right and lower left terminals) appear to be traveller wires - either both going to the sister 3-way switch or 1 going to the sister switch and one going to the light, depending on where in the wiring chain this switch is located (probably the former as per my original assumption). These two black wires would connect to the two traveler wires on the HS210 with wire nuts.
  • Then, you need to to connect the white (neutral wire) of the Kasa to the wire nut in the junction box holding the other white wires.
  • Then connect the green ground wire of the Kasa to either the wire nut holding the other green or bare copper wires or directly to the ground screw in the box (I can't see clearly).

1. Of course, this assumes that you have a pair of 3-way Kasa switches.
2. If you bought one Kasa 2-way switch, you can still wire it in the box but the other sister switch (not the one to the right) would be rendered inoperable.
3. With the extra wire nuts in the junction box, the box will be VERY cramped and may not even fit all the wires as the Kasa box is pretty bulky itself. That would suck and would require other space making solutions.
4 . I am NOT an electrician and just going by the pictures and limited understanding of your circuit wiring without the benefit of testing what's what with a multimeter. But I have survived doing a bunch of wiring in my house. Even so, I'll probably end up electrocuting you.
Last edited by DiceMan on Sep 18th, 2021 11:58 pm, edited 3 times in total.
Nov 10, 2019
429 posts
Nuts... Looks like mine is 1 way switches...


Thanks a ton tho I'll be shopping for a 3way switch instead now and try this
Mar 8, 2013
436 posts
If you don't have a simple voltage tester or multimeter, please consider investing in one (cheap $20 ones are fine) for basic home repair. It'll help you figure out which wires are line or load.

Both those switches look like 3-way switches at a glance, but it's hard to tell. Do you know if there is another switch that controls the same light fixture? Can you post images of the side and back of the switch you want to replace? The switch on the left could still be a single pole switch without knowing more info.

Here's a schematic for a 3-way:

3-way switches have a line wire (connects to the service panel), a travel wire (connects to other 3-way switch for the light fixture), and a load wire for the light fixture.

Single pole switches have a line wire and a load wire. But some homes have these switches wired with multiple line wires (one from the service panel, and the rest go to neighbouring light switches). Sometimes there will be a line wire connected to the push-in terminal on the back of the switch, and another line wire wrapped around the screw terminal on the side of the switch.

In your photo, the switch on the left has 4 black wires. It looks like there's a short black wire connecting the two switches; that would probably be a line wire, where the switch on the left has two line wires wrapped around a screw terminal. One of the remaining black wires on the left switch would be load, but the other black wire could either be a traveler wire for a 3-way switch or it could be another line wire (can't really see where it's connected from the angle of the photo).

I had to wire a similar dual gang switch box, and one was a 3-way switch and the other was a regular single-pole switch.