# 3- and 4-way switch circuit question

All my 3- and 4-way switch circuits (and even one 5-way setup) are wired the same way for dumb switches/dimmers. Line-in goes to the first switch box. 12/3 goes from the first switch box to the last switch box (through the intermediate switch(es) when necessary), and 12/2 load goes to the light. We laid out and wired it so that the "last" box in the circuit is always the one that would make the most sense location-wise for a dumb dimmer.

Zooz and Inovelli wiring diagrams (for their switches and dimmers) show how to wire their smart switch/dimmer in the first (line-in) box and use the existing dumb switches for the other switches.

The Zooz and Inovelli diagrams also say that a dimmer cannot be in the last box (load side).

My question... when replacing the first dumb switch with a smart switch (e.g., ZEN76), why can't a dimmer be in the last box and what happens if it is? I can see some problems using a smart dimmer in the first box and a dumb dimmer in the last, but why does a dumb dimmer in the last cause problems for a smart switch?

I know there are other solutions to get a dimmer in the last box, e.g., add-on switches, multiple smart dimmers, different wiring methods, etc., but I would like to know why a dumb dimmer can't be used.

So you basically have the below diagram (any number of additional 4-ways can be added).

If the left hand box was an ON/OFF switch and you had a dumb dimmer in the right hand switch, you should be OK. The dumb dimmer must be a 3-way and designed to run with LED lamps. Verify such a dumb dimmer exists without having to have a line-in connection.

There are 2 problems using a dimmer at the load.

1. You won't be able to turn the light full bright with the smart switch when your dumb dimmer is at the lowest setting.
2. The smart switch will not have enough voltage to know when you turn on/off the dimmer with lowest setting.

As long as you keep the dumb dimmer at full brightness then it will work but that's not ideal or practical unless you are the only person using the switches.

You won't be able to turn the light full bright with the smart switch when your dumb dimmer is at the lowest setting.

I understand that the dumb dimmer level will always control the brightness, e.g., if the dimmer is set to 50%, the light will be at 50% when turned on from the smart switch. That's what happens when the switch and dimmer are both dumb, so I'm okay with that.

The smart switch will not have enough voltage to know when you turn on/off the dimmer with lowest setting.

The smart switch would be connected to line-in, so it would always have full power, regardless of the dumb dimmer level.

Here's an example... 3-way setup controlling porch lights. Dumb (3-way) dimmer is on the outside wall so that lights can be dimmed (and turned on/off) from the porch without going back into the house. Line-in 3-way switch is on the inside wall so that the lights can be turned on/off without going outside on the porch.

Here is a link to two Zooz 4-way wiring diagrams. Note that option 2 is what I have, and it is logically equivalent to what @JohnRob posted. Also note that both "after" diagrams show "NO dimmers / smart switches" on the dumb switches.

It's the volt of the dimmer going to the traveler of the smart switch that's the problem. Not sure what zooz switch needs but there need to be a change high enough for the smart switch to detect.
This is with just dumb non-electronics dimmer. Electronics dumb dimmer is even more troublesome.

One of the Zooz dimmers has the option to use a momentary switch on the other end which can then be used for dimming using a press and hold action. May only work on 3-way and not with more switches.

I have installed one like this in my house, I NEVER use it. In fact I rarely touch ANY of the switches, especially not to adjust the level on them. I have the dimming levels pre-programmed to what is desired during certain times of the day. The one thing I do use occasionally is a double tap up to set to 100% which you only get on the smart switch, or you can setup the momentary switch option for that also.

Also, at the cost of those dimmers you are looking at, you might as well just add more Zooz dimmers instead and then setup mirroring in the hub (or associations) as a virtual 3-way. You could wire the red traveler straight through from the first box to the light and connect to the load on the first switch. Then connect the black/white into the line feed to give power to the other switches.

@jtp10181 I understand there are several ways to do this using smart switches and/or add-ons and/or some dumb switches. I am just curious as to why a dumb dimmer doesn't work, but a dumb switch (without LED indicator and/or illuminated paddle) will work.

I did some more digging and found this on the Zooz website...

But as a result you can only use regular 3-way on/off switches in your multi-point control set ups. That means no regular switches with LED indicators or illuminated paddles either - this is because the "dumb" switch (regular on/off) in the 3-way only gets an electronic signal through its neutral; it doesn't actually receive any power. The LED indicators on these switches require power to light up, so it may pose problems with the installation.

The Lutron DVCL-153P dumb 3-way dimmer doesn't have a neutral connection, and it doesn't look like it has an LED indicator or illuminated paddle. This dimmer supposedly works with LED bulbs.

Maybe there are some dumb 3-way dimmers (without indicator/illumination) that do require a neutral and won't work even if there is a neutral in the box that could be used, so it's easier to just say none will work and avoid confusion/problems.

If you are so sure it will work just try one. Worst case you fry the dimmer and smart switch.

No one is going to tell you that its a good idea, no matter how much you argue about it.

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I still think the easiest, most featured, and safest way is to use one smart dimmer, and button controllers at the other locations.

I first started to do this with my Caseta, as they don't have 3-way setup no matter what. Later I started using Pico remotes and Zooz dimmers together to make a virtual 3-way. If I didn't have a Lutron Caseta system, I would probably go for the Zooz remotes, either the Zen 34 paddle, or the Zen37 if I wanted more buttons in a particular location.

Put the smart dimmer where the power originates, and cap the other wires OR if the power and light fixture wires are in different boxes, you can rewire to send power to the needed box.

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There are "aux" switches which connect to the dimmer by only 2 wires (neutral and a line). They can be placed in the non dimmer locations and give full control at every location. I've not used them myself but I read others have with success.

Just to be clear...

In my first post, I said "...I just want to know why...". In a subsequent post, I said "...I'm curious...". I have not asked for alternative solutions. I've twice said I understand there are other solutions. I've bench tested two of them (Zooz and Jasco) and received some additional wiring advice from Zooz,

I'm curious by nature and like to understand "why not" when I'm told something can't be done with no explanation (although the Zooz doc kinda went there). I know I can find out the hard way, e.g., fry some hardware. I simply thought that someone might have been through this and/or has a better understanding of electronics than me could provide an explanation.

I know enough about electricity and electronics that I can tell you it sounds like a bad idea, but donβt have any technical data to back it up.

I use the Leviton DZ6HD in the main box connected to the lamp. Then use DD00R dimmer companions in the other locations. This allows full dimmer control in all locations. This setup need power and neutral in the main box. I have had to pull some new wires in locations that didn't have the neutral.

The dumb dimmer could be installed in a first or last box but all other switches must be either dumb mechanical or smart relays (which are also mechanical).

Nice, did not know Leviton had that option. Looks like that Leviton "aux" switch will work as an adder for dumb dimmers or smart dimmers. https://www.leviton.com/en/products/dd00r-dlz