Blue series 2-1, non-neutral, 3 way, fan/light fixture, only control smart bulbs?

Hello, I still haven’t gotten my blues in, but thought I’d ask about this to make the time pass.

We have combo ceiling fan/light fixtures that are on the same switch. For some of them, we were able to use smart relays on the fan so that is no longer tied to the switch. For two of them, the relay only works when the wall switch is on, so it seems they are still tied together and I’m assuming the blue series switch is still a no go for this setting. One of these is also in a 3-way circuit.

Is it possible to set up the wall switch (with no neutrals) to not actually control/connect to the load to the fan/lights, and instead have the light/fan fixture wired as “always on” and use smart bulbs controlled by the switch (through home Assistant)? And if so, are there wiring diagrams?

Along with that, is there a way to have the blue switch not control the load but still use a white series aux switch in the three way setup, or would we need another blue acting as a remote, so to speak?

So for your first question, if I understand you correctly, yes.

If you have a fan/light without a neutral in the switchbox, that means that a hot and neutral is present at the fan box. There is a 2-wire between the fan box and the switch box. It is wired in what is known as a switch loop. The hot (only) is sent to the switch box usually over the white conductor and returned to the fan box switched via the other (usually black) conductor. Because both of the conductors are used for the hot/switched hot, there is not neutral present in the box.

The solution is to change the connections at the fan box. Connect the incoming hot/neutral to the hot/neutral of the fan and fan light feeds. To control the fan remotely, connect the fan via a smart relay. To connect the lights remotely, either use a relay or use smart bulbs.

Additionally, connect the incoming hot/neutral to the 2-wire going to the switch box. You now have a hot/neutral at the switch box to power the Inovelli, which without a wired load is a scene controller. You can now control the fan via scenes using the multitap capability of the switch. You can control the bulbs via scenes as well, or via binding if your bulb(s) are Zigbee.

This wiring is straightforward, but as you asked, I can draw it out if need be.

I believe the answer is if you are going to use scenes/multi-tap to control the non-wired load, then the Aux will send those button presses. But if you are going to use binding to control Zigbee bulbs, then you would need a 2nd Blue.

@harjms ?

Thank you for such a detailed answer! We’ll probably wind up using the switch as a scene controller, especially if we can use the aux switch. If you can draw it out that would be super helpful, but no rush, especially since we don’t have our switches yet

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Just so I understand -

You’re asking if you can still use a Aux switch in a 3 way setup that has the Blue switch in SBM, but to still relay commands/scenes from the aux switch without effecting SBM load?

And just so I’m clear too. The first scenario I described above involved a rewiring of a switch loop, so I’m not sure if there will be a load on the Blue in the 3-way. It’s not clear to me if this is one scenario or two.

I’ll try to explain all of it. I can draw up pictures if needed.

Current setup:

  • four rooms previously had combination fan/light fixtures controlled by the same switch (and pull strings).

  • In two of these (“good rooms”), we have used a Shelly 1 smart relay to separate the fan & light, so now we can have the wall switch (that controls the lights) off & still turn the fan on/off with the relay, so I think we are good to go with our inovelli’s there.

  • There are two “bad rooms”. One has a three way switch setup controlling the fan/light, the other doesn’t.

  • a Shelly 1 smart relay is on the fan portion of the fixture in both rooms. We hoped this would completely separate the light and fan, like it did in the “good rooms”, but if the wall switch/light is off the Shelly looses power & can’t be controlled, which shows that the fan is still somewhat controlled by the wall switch in both “bad rooms”

If there is another wiring method we can try in the bad rooms let me know. We wired them up at the fixture the same as in the good rooms, but maybe we missed something

What I’m considering is this (I’ll number it too so we can reference points)

  1. smart bulbs in fan/light fixture, constantly powered and controlled by Home Assistant (likely through a zigbee hub, maaaaybe wifi). I’m not exactly sure how we will wire this, but my husband is pretty sure we can (he did the other wirings since he has more experience with circuits, but we’re both mechanical engineers).

  2. fan controlled by a Shelly 1 smart relay (for this idea it would be in parallel with the light in step 1, because if it isn’t then we can skip all this and do our original plan)

  3. blue series switch working as a scene controller, hooked up to power but not controlling the load going to the combo fan/light fixture (so I don’t think it would be in SBM since we shouldn’t use the switch on a fan)

  4. either another blue series or a white/aux in the other end of the three way, or however it needs to be for it to control scenes (lights). The other “bad room” only has a single switch and doesn’t have this problem.

I know this is a ton of info and probably isn’t super clear. It’s a house from the 50s with random added rooms and the wiring doesn’t seem to be consistent throughout the different additions.

Sounds like those are switch loops which I described before. I will draw the solution.

@harjms can address whether or not and Aux can send button events to a Blue that does not have a wired load.

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So for your “problem” switch box(es), if I understand correctly (forgetting about the 3-way for now) you have a switch that has only one 2-wire (not counting the bare ground) in the switch box, and that controls both the fan and light together. If that is the case, there is a hot and neutral in the fan box, and the wiring topology is a switch loop, as I described above.

A switch loop looks like this. You can see how both of the conductors to the switch are used for the constant hot and switched hot and hence, no neutral at the switch.


One of the characteristics of a switch loop is that most often, electricians will send the constant hot to the switch over the white conductor, so you’ll often see a white/black connection in the light box. There may or may not be a piece of black electrical tape wrapped around the white conductor in the switch box, indicating that the conductor can be hot.

So the solution to eliminate the swtich loop and use an Inovelli to control both the fan and the light is the following:

  1. Re-wire at the fan light box so that a hot and neutral are applied to the light(s)(presuming you will use a smart bulb(s), a smart relay, and the two conductors going to the switch. Connect the fan to the relay’s outputs.

  2. At the switch box, wire the now present hot and neutral to the Inovelli’s hot and neutral terminals. It can now control things via scenes/multi-tap or binding if your bulb(s) are Zigbee.

Looks like this. For the 3-way, if required, use the 3-wire between the two switch boxes using two of the conductors to connect to an Aux switch.


That makes sense, thank you! Our switches have had the label printed in what looked like the last group, so we should get them in the next week!

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Jumping in this thread a bit late. I have the same setup, and my blues are also on order. Did you get this to work as in the diagram? Whay relay did you use? I’m having trouble finding one that can handle the load of a fan motor… Thanks!

Hey! We wound up using Shelly relays and ikea smart bulbs. We have the inovelli switch set up in smart bulb mode and coupled with the light bulbs. We use home assistant and set up the Shelly’s to that, then have one button (the config/favorites one) on the inovelli set to toggle the fan, which is really nice!

We still haven’t set up our three-way fan/light setup but plan to do so the same way just with two blues in smart bulb mode controlling the same bulbs

Oh, nice, and thanks for the quick reply! Do you have control over fan speed in this setup with the Shellys?

We can control fan speed through basic pull strings but not smartly. Our fans aren’t high-tech enough to do it anyway so it wasn’t something we looked into. It would probably depend on where you put the shelly. But if you have a way to control just the fan smartly already, the easiest bet would probably be to just use smart bulbs and set up the switch in smart bulb mode without connecting to the line wire

Gotcha. Thanks so much!