3-way wiring. Where to put the aux switch?


I’m trying to understand, based on my existing 3-way wiring, if I would need 1 smart switch and 1 aux add-on switch or 2 smart switches?

And in case I would be good with just 1 smart switch, where in the circuit the smart switch and the aux switch would need to go (in case only one placement is possible).

Here are pictures of my existing wiring:

Switch 1:

Switch 2:

Based on what I see in my switch #1, it looks similar to the wiring of the switch connected to power source seen here:

The difference is that it’s not two white wires that connect together but a white and a black. Could it be that it’s just that wrong color wires were used in my setup ?

Yet, the wiring of my switch #2 does not look like in that schematics.
It looks more like in:

as I seem to only see 3 wires for that switch.

[EDIT] I had not seen it before, but maybe it’s rather that third schematics that seems to fit all my wires (except for the white / black mix):

Is there a way to validate that without unscrewing the fixture ?

I don’t intend to install that myself. For now all I want is to understand what I need to buy.
The thing is that if I can manage with only 1 smart switch that would be less expensive and I would not have to rewire things.

Thank you.

Are all three conductors attached to switch 2 from the same 3-wire? It’s tough to tell because the black attached to the common screw disappears behind the other switch. It’s best to get a picture with the wires pulled out completely so that we can see the connections to the switch and clearly into the box.

I’ll try to take a good look at it again next weekend (i don’t live there yet), but here is a picture of the wiring of the two smart switches (Jasco) beside it, even though it is also not showing the wiring inside the box.

You’re also going to have to do some testing with a meter.

Sorry for the neophyte question, but what testing should I do ?
I don’t know anything about electrical stuff. And I don’t intend to install the new switches myself.

I just want to figure out what to buy, because if my setup is like the third schematics I included in my previous post, it looks like it’s not even an Inovelli aux add-on I would need to buy but rather a GE or HomeSeer one.

The testing will help determine your wiring scheme. What you test with a meter will depend upon the answer to my question about If all three conductors from the three wire are attached to switch 2.

Giving your lack of electrical knowledge and the fact that you aren’t going to be installing the switches, I don’t recommend you do any testing. The testing is really to determine the configuration and not to help you determine what to buy.

I think you will be fine with a switch plus and aux switch. Btw, there is no real difference between the Inovelli aux and the other two that you mentioned. They all serve the same purpose.

I don’t believe that you will be able to use two smart switches without rewiring at the light. I suspect, but I’m not certain, that you have a non-neutral situation at switch 1. If that turns out to be the case, then you would not be able to use a smart switch at switch 2 without rewiring at the light.

1 Like

The Inovelli does have a config button which the other two do not.

1 Like

@Bry Thank you very much for these detailed answers.

I don’t even understand what a “conductor” is… :rofl:

So why do they specifically show in the third schematics an aux switch from a different brand than Inovelli like we can see in the two other schematics ?

If I don’t have to, then I would indeed prefer to not use two smart switches as long as I can use the smart one in replacement of my switch #1. Well, to be more precise, if I can’t use a smart switch at switch #1, then I will have to forget my idea of using the new upcoming motion sensing switch as it only make sense to put it at switch #1 location.

A conductor is a wire. So what I was asking is in switch 2, I think you have Romex wiring which has three insulated wires and a bare copper ground wire. Are all three wires connected to switch to (ignoring the bare ground) from the same Romex sheathed cable?

Not sure about the picture difference in the schematics.

At this point, I believe you will be able to put the Inovelli and switch one and the aux switch in switch two. That’s solely based upon looking at the pictures you posted. Testing will need to be done to confirm.

1 Like

Bare copper! :wink:

Lmao. How long did it take you to find that?

I am notorious at dictating things and done not reading what I wrote.

Surprisingly not that long

You still need to post clearer pictures of the wires on the second switch.

It looks like a switch loop in box 1 with a 3-wire going to box 2. No neutral and doesn’t match any of the drawings you posted. Switch goes in box 1 and aux in box 2.

Here are pictures of the wiring of switch #2.
As I don’t know what is useful/relevant I include a bunch.

In the box shown switch #2 is the dumb one at the right.
(btw : the two on the left are Enbrighten smart non-dimmable switches that I intend to also replace with Inovelli ones).

Wiring explanation in words:

The black wires coming out from the two left boxes are tied together and from there there are black wires going to eaches of the three switches.

The black wire coming out from the right box is attached to the the two white wires coming out of the two left boxes. From there, only two white wires go to the two left switches.

The white wire coming out of the right box goes directly to the right switch.

Each of the red wires go directly to each of the switches.

Well, it’s not what I thought it was . . and now I know why.

What I’m seeing is a line in Box 2 and a load in Box 1. I’m going to describe your wiring topology so you understand what you have. The conductor colors are not used according to common convention. While that is not wrong, it’s confusing.

The line box is Box 2. Power is fed from the black bundle to the black common screw on the switch. Inexplicably, whoever installed this chose to use the red and the white as the travelers in the 3-wire. That leaves the black in the 3-wire to send the neutral to the other box. That’s why you see that black conductor in the white neutral bundle. Not incorrect . . just . different.

The load box is Box 1. The white and black travelers from the 3-wire are attached to the two non-common screws on the switch. The load Romex (to the light) is the 2-wire. The black from the 2-wire is connected to the common screw on the switch. The neutral (which comes into that box over the black) is connected to the white from the 2-wire, which explains why you see a white and black bundled there. Not incorrect . . just . . different.

You should confirm the connections I have described before proceeding further. If they are correct, I’d say you could put the Inovelli in either box so long as you are mating it with an Aux switch. Either of the following diagrams should work. Box 1 is on the right.

1 Like

Thanks a lot @Bry. To be honest, I don’t understand anything of what you said. I read your reply 3 times and it did not help. :laughing: The fact that I don’t even understand the vocabulary is killing it straight from the start.
As I mentioned initially, I don’t intend to install that myself, so as long as I know what I can buy (and know it can be placed where I want) and that a real electrician will understand the wiring I have, then I’m fine.

So, what I understand in the end is that I’m not in a bad situation and so I can put the smart switch in any of the two places, as long as one of the two switches is an aux add-on switch (i.e. I cannot use two smart switches in that wiring setup).

Again, a big thank you!

Yep, no worries that you don’t understand since an electrician is going to do the install. My writeup may save him 5 minutes or so of wtf’ing with that black neutral wire. (He’ll get it . . .)

So from what I see you have a perfectly standard neutral installation line in one box, load in the other. So you’ll be fine with a Red or Blue 2-1 and an Aux.

You can use two 2-1s as well, but the wiring is slightly different. It will also require you to bind or association (depending on Zigbee or Zwave) the switches together via your hub. You can’t just wire two 2-1s together and get them to work.

Glad to help.