3-way + dumb, with blue replacing dumb switch at the load side

Hey all, I am outfitting my home with Blue 2-1s. I did a bunch of single-pole switches without issue, but the 3-way is giving me trouble.

It’s a hallway with a 2 switches, one dumb. My breaker box is below switch A (dumb), then there are 3 pot lights along the hallway, and a smart switch B at the far end. So my assumption is that I have the line side by switch A, but I am actually trying to replace the switch B with the inovelli, which is different than the wiring diagrams which all have it on the line side.

When I wired it up I copied the labeling from an outgoing smart switch which was working for me (meross), but now the dumb switch is cutting power to my inovelli. What I had as the traveler and line seem to alternate delivering current depending on which way the dumb switch is.

After studying the diagrams here: Blue Series 2-1 Switch • Wiring Schematics | Inovelli Help Center
For Multi-Way (3-Way) + Dumb / Existing Diagrams WITH neutral they all show the inovelli being installed on the line side. Can I install It on the other side or no? Maybe my meross switch supported this and the inovelli does not?

I don’t think you’d have enough conductors to send Line, Neutral and two travelers from Box A (Dumb) to Box B (Inovelli) if you wanted to keep the Box B as the smart switch. You could install an add-on (Aux) switch and make it work though.

That makes sense. So my assumption is that the old smart switch was able to intelligently switch from taking power through either traveler wire?

Potentially or your other smart switch didn’t require a neutral. You can wire it as non-neutral, but non-neutral doesn’t support dumb switch as the “3rd” switch. If you have a part number of meross, we can try to look it up.

Also, pictures are worth a thousand so if you have any pictures of your in box wiring, we can also take a look to see if there’s anything being overlooked.

Aux Switch in case you want to look at that version:

I made a quick video and also included the pic of my old Meross 3 way switch.

This is after I switched the dumb and smart switch locations, as I am fairly certain that the line side is where the smart switch is in the video.

Any help is appreciated!

So since the video I have changed the dumb switch’s wiring so that the load is on the common screw. With that I believe my setup mirrors “Line/Load in separate boxes”:


And with power it is acting weird. I can switch the lights on/off from the inovelli OR the dumb switch, but if I turn it off the dumb switch, the inovelli goes powerless and cannot turn the lights back on.

Also while on, it seems like all the lights are dimmer and is causing one of the bulbs to flicker I think this is actually a fluorescent or some different type, so maybe just a bulb type issue, but they do seem dimmer, and dimming is not enabled.

Seems like power definitely comes to the dumb switch first. I’m not sure how the merose switch maintained power if it is in the same spot as the Inovelli.

Ok so I pulled everything back out and tested the wires. Indeed I have load and travelers by the dumb switch, NO line. So I got the switches wired up very confidently, plus used a new Blue and Dumb 3-way to rule out faults there, and flipped the breaker on. At first it worked perfectly, UNTIL I flipped the single-pole inovelli next to it (which otherwise is working fine). This seemed to throw my 3-way into bad state. It no longer received power when the dumb switch was off, and when on it ran the lights at about half-brightness (even though it is not a dimmer)

I’m not sure what to make of this. I don’t have any home automations set up that would tie them together. They do share the neutral bundle in the box, but I’m not sure what the issue is.

I also read around 44v on the neutral while I had just the single pole installed and “off”. Not sure the significance of that but just thought to mention in case it tells something.

Got it! The problem was a weak connection to the neutrals. I had many moments where I thought it was good but then a slight jostle would weaken the connection and cause some sort of problem.

Glad to see you got it figured out!