Replacing broken, dumb 3-way switches with smart switches

This might be a bit of a convoluted write-up, but - I would like to convert 2 different outside lights (referred to below as ‘patio’ and ‘backyard’) to smart switches (Zooz ZEN26). Each of the lights consists of 2 CFL Flood bulbs of 23 watts each. Each of the 2 lights is on a set of 3-way switches. Complicating this is that both sets of 3 ways are not functioning quite right with the old dumb switches. The switches are in 3 different switch boxes - Box #1 has 4 switches in 3 gangs (I believe both smart switches will end up in this box). Box #2 has 2 switches in 2 gangs, and Box #3 has 1 switch in 1 gang.

Summary of how the old, dumb 3-way switches currently function:

Backyard light:
Box #1-down > Box #2-up > light OFF
Box #1-down > Box #2-down > light OFF
Box #1-up > Box #2-down > light ON
Box #1-up > Box #2-up > light OFF

Patio light:
Box #1-left > Box #3-up > light ON
Box #1-left > Box #3-down > light ON
Box #1-right > Box #3-down > light OFF
Box #1-right > Box #3-up > light ON

In order to fix the Patio light switches so that the light is properly toggled when either switch is flipped, I believe all I need to do is move the black wire from ‘A’ to the currently unused screw terminal.

As for the backyard light - I am stumped as to why that set of switches isn’t properly toggling the light.

Once I have verified that the old dumb switches have been fixed to operate properly, I will re-arrange the switches in Box #1 when I install the smart switches. I will also be replacing all of the other, unrelated dumb switches with new ones (they’re all old and discolored). The Patio 3-way switch will be swapped places with the 3-way switch labeled as Office Outlet, which will allow one full gang for each of the new smart switches. Dumb switches will be on the double switch.

Wire notes:
B (or F?) - goes go Breaker #20
F (or B?) - goes to Office Outlets (just a guess)
I - This probably goes to the backyard light fixture, but I’m not sure why the outside sunroom light would be tied off this wire.

Diagrams of the current wiring:

You should get in touch with support from the smartest House. (Zooz is their house brand) They are very good at helping with wiring questions regarding their switches. :sunglasses:



Since you are making them smart you could chose to make the circuit a simple single switch and abandon in place the third switch. I had a three way switch for my kitchen, I have an assistant (Amazon Echo) in my kitchen also, so instead of messing with a three way, I installed a single throw smart switch in my highest traffic area and did not connect the other switch. Now I can just voice activate the kitchen lights, or use the smart switch. If you use the “abandoned” alternate switch nothing happens, as it is just dummy.

You’ve got a lot going on there.

Some general observations.

  • As you most likely know, you can install the ZEN26 and use a dumb switch on the other side. So you’re right to first get the dumb switches working.
  • The Zooz smart switches will need to be in the box where power from the breaker comes in.
  • Agree with @jdroberts about contacting Zooz support, they’re very, very good.

I’m looking at the patio 3-way and agree it’s not wired correctly. One of the terminals on the switch should be black. That’s the “common” terminal, you didn’t label the common terminal on the patio switches as you did the others. In Box #2, that should be where the black wire going to the light is attached. In Box #1, the common terminal should be where power from the breaker comes in. That looks like it’s the jumper from the Inside Sunroom standard switch.

So for the patio 3-way in Box #1 you should have:

  • Jumper from sunroom switch connected to the black, common terminal.
  • Red and black traveler wires from you cable marked A connected to each of the brass terminals.

I noticed you drew the Box #1 patio/sunroom switch differently. Is it a dual switch in a single gang? I’m wondering if it’s the result of a remodel where someone squeezed an extra switch into an existing 3-gang box. I’m speculating a lot based on the diagram but if it’s a dual switch, it’s possible that the part controlling the patio lights isn’t actually a 3-way.

The diagram is good, pictures would be helpful also.


Thanks for the tag @JDRoberts!

@iridris we provide step-by-step wiring instructions for Zooz switches so you can get in touch with us or Zooz support directly, just send images of the wiring in each box and your order number. BUT we can only help if you have fully working 3-way switches since identifying connections remotely is only possible if we know exactly which wire does what. If the switches aren’t currently working well, that means the wiring can be misleading and we wouldn’t be able to get that fixed without being on site for your safety.


So I finally got some time to dig into this and was able to get the 3 ways functioning properly, and was then able to install some smart switches. I was even able to do a 3rd smart switch thanks to the location of some of the wires.

The wire labelled “D” did not go to the breaker, it actually went to the light fixture. Once I figured that out everything made a whole lot more sense. Wire “I” ended up being from the breaker.

To fix the 3 way for the back yard light, I just swapped the white wire going to the 3 way switch in box 1 with the black wire coming from wire “C”. I was then able to install a smart switch in box #2.

To fix the 3 way for the patio light, I just moved the black wire from wire “A” to the extra screw on the 3 way.

After rearranging the switches, I was able to install a smart switch for the patio and for the sunroom. The office outlet and backyard 3 way switches in box #1 are now on a dumb double 3 way.

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