Aeotec Nano Switch 3-way Wiring

In an attempt to make automating some 3-way lighting cheaper, I picked up an Aeotec Nano Switch. From the description and documentation, it seems like they should work in 3 and 4 way lighting environments. However, I’m having trouble figuring out the wiring because I don’t understand how it works internally.

The light I’m current trying to install this switch on is in a typical 3-way switch circuit, with the line wire going to the first switch, 2 travelers going to the second switch, the load from the second switch going to the light, and the neutral at the light returning back to the circuit breaker. Like this:

Wiring Diagram

So what I don’t understand is what I need to do to get the Nano Switch working in this circuit.

Aeotec Nano Switch 3-way diagram

Things I’m pretty sure of:
-Neutral slot gets a neutral wire to the breaker
-Line slot gets a line wire from the breaker
-In gets a line wire from the breaker

I’m not quite sure how to wire up the Out, S1, and S2 slots, as well as where the existing switch should be. My guess is that I still need a live wire going to the switch’s common post, and then do the 2 travelers get bridged and connected to S1? But then what do I do with the 2 wires going to the second switch? Is one connected to Out, and the other connected to S2? That seems wrong unless the switch has a few relays inside.

Is this possible with my existing wiring, or is it necessary to change up the wiring and get a direct load wire into gangbox 1? Then bridge the 2 travelers from gangbox 2 and connect those to S2, and connect another live wire to the switch in gangbox 2?

Thanks for the help!

I’m not an electrician, the way I read the diagram is the load wire to the light runs from the out of the nano to the light. Other side of light connects to neutral.

The line goes to both switch common connections. Then the 2 sides of switch1 both go to the switch 1 connection, and the 2 sides of switch2 go to switch 2 connection.

Thanks for the second pair of eyes. Now, given that this requires the S1 and S2 slots, I was wondering how it would work in a 4-way lighting situation. In a 4 way situation, if I can still put this in the same box as one of the 3 way switches, should I just be able to connect the 2 wires going to the 4 way switch and plug that into S2, allowing switches 1, 2, and 3 to work with the Nano Switch?

I don’t remember, I believe there was wiring diagrams on there websight for the different options. I’d have to look it up and see. I’m out of town for a few days before I can get to my computer

This is pretty fascinating between the crappy instructions from Aeotec and the European wiring!

Now, the principle behind a regular 3-way switch is that there is always hot going through one of the travelers. If you think about it, all you’re really doing is mirroring 2 single-pole/double throw switches to each other.

But I think the premise behind this switch is that you move the hot side control completely to the nano switch for the load output and the wall switches are just a normally open/closed toggle on whether the “out” terminal sends power to your light or not.

It also would seem as if the 2nd switch is completely superfluous as well. I’d be testing that thing left and right with a meter just to understand the darned thing!

Anyway, all my rambling aside, seems as if someone encountered this and got some help directly from Aeotec (Aeotec nano switch DTH?).

So, I hooked this things up today and it almost works. First of all, the documentation appears to be wrong. It says Parameter 120 sets the switch mode, but the value of 2 appears to be for a 3-way switch configuration. 120 appears to be for S1, while 121 needs ot be set for S2.

Now, I’m still having a little trouble. The existing physical 3-way switches have Line going to common, and the 2 travelers are connected and inserted into S1 and S2 respectively. The switch that’s in the same box seems to work, but the other switch never triggers the Nano Switch. The only thing I can figure at the moment is that the switch that doesn’t work is actually connected to a different Line wire, controlled by a different breaker. There was another Line in that box, so I used that to avoid having to turn one of the travelers into another Line wire. Would this affect the way it senses the external switch at all? I’m not sure what else could be going on.

You kind of have to forget the normal way of wiring this. The normal way to wire a 3-way is that you run your hot through the travelers so each switch can open or close it to the light/load. You always have hot on one of the travelers in a normal 3-way switch. The switch closest to line determines which traveler has hot and the switch closest to the load picks which traveler it’s going to use to feed the light.

The issue with the nano switch is that it has to have the line and the load in the same box to work. Then you turn your physical switches into a simple toggle. The 3-way switch mode basically just means that when it senses a change, it will change the output of the switch. And, yes, the Aeotec website mentions parameter 120, but that only controls the first switch, while parameter 121 controls the second switch - but since you actually shouldn’t need to use both anyway. The S1 and S2 aren’t actually for processing the line, like a normal switch - they are just a toggle for the nano. The key is what it uses to trigger the switch. For example, the nano dimmer requires that the switch terminals are just to ground (just an open/closed loop) - but I think the nano switch may do both. It appears from your initial work, that it will take 120VAC there - not sure if it will take common or not.

If you have line in both gang boxes and they are on the same breaker, this can work. If not, you’ll have to get another line from one box to the next - either running an extra line/hot to the box with the load (2nd box) or to pull the load back to the 1st box.

So, assuming they are the same breaker, put the nano switch in the 2nd box and put all the 1st box wiring back the way it way, ie line going to common and then the travelers headinging out of that box.

In the 2nd box, put the nano switch.
Obviously hook your neutral up to the N terminal
Hook the line in that box up to both the L terminal on the nano switch and to the IN terminal
Hook your traveler wires to the traveler terminals on your 3-way in that box.
Connect your load wire to the OUT terminal of the nano switch.
Connect the common terminal of the 3-way to S1 of the nano switch

Alternatively, if you aren’t sure/can’t/don’t want to figure out if the line in both gangs is the same circuit (it probably is though), you can run everything from the 2nd box. If you want to do this, let me know and I’ll detail that out - don’t want to muddy this post up anymore than it is already!!

This is still a fascinating problem! And I think I just figured out how to do it if you don’t have line in the 2nd box! This is all predicated on the 3-way mode of the nano just being a change of state, which I’m pretty sure is the way it works.

First, for the sake of argument and say your wiring is the standard 3-way wiring with black, red, and white conductors (will make it easier to follow).

Now, in the first box, connect the line in to the common terminal of the switch and to the black wire that goes to the 2nd box.
Connect the red wire to one of the traveler terminals. The other terminal will have nothing connected.
Connect your white(neutral) to the white wire going to the 2nd box.

In the 2nd box, where the load line is, you’ll put the nano switch.
Connect the black wire from the 3-way to L and IN of the nano switch as well as the common terminal of the 3-way switch in that box.
Connect the red wire from the 3-way wire to S1 of the nano switch.
Connect a wire (any color you want!!) from one of the 3-way switch traveler terminals to S2 of the nano switch. Again, the other traveler terminal will have nothing connected.
Connect your load wire to the OUT terminal of the nano switch.
And, of course, hook your neutral line (should be the white wire from the 3-way) to the N terminal of the nano switch.

Now, each switch will flip the power independently. What you’ve done here is effectively turn your 3-way switches into standard 2-way switches because in one position, nothing comes out of the switch. But each switch will use a different terminal on the nano switch and throw 120 or nothing to that terminal.

So I do have a Line in each box. I undid all of my previous wiring and did what you suggested first, wiring the remote switch with Line on COM and COM of the local switch going to S1 on the Nano Switch (the local switch being the physical switch in the same box as the Nano Switch). So now the 2 switches are acting as a 2 way switch, so I’ve set parameter 120 to 1.

There appears to be voltage on S1 and S2, about 60v. With the output from the switch going to them, the lower voltage appears to be about 30v and the upper voltage is 120v. I feel like it’s almost working, but it’s very strange. First, the physical switches only seem to turn the Nano Switch off, not on. The drop from 120v to 30v seems to always turn the lights off if the Nano Switch was On, but doesn’t turn the Nano Switch On if it was Off. The jump from 30v to 120v hasn’t triggered the Nano Switch to do anything. I’ve reset it a few times to make sure that I hadn’t messed anything up with ZWT, but this is the farthest I’ve gotten. Any ideas of something I might be missing?

One other funny thing is that when 120v is going to S1, if the lights are on and I check it with a multimeter, removing the multimeter triggers the lights off as well.

Look at the wiring diagrams in the customer pictures section of it’s big brother, I wonder if S1 and S2 are simply the switch ports like on the other device, that would seem logical.

Even though they are acting as a 2-way switch, you want them to be programmed as a 3-way switch. The “3-way switch mode” operates off sensing a state change, so by programming them to be 2-way, you defeat that. Reprogram them to 3-way mode (in either of the setups I suggested) and see if it works.

Nope, setting it to 3-way mode and toggling the physical switches, whether the Nano is in the on or off state, doesn’t ever trigger it. I’m really confused, I agree that your suggestion should also work.

OK, I just took the existing 3 way switches out of the loop and wired up a local 2-way switch. One end of this switch was connected to the same Line as the Nano Switch, and the other end was connected to S1. Go figure, this worked perfectly. In 2 way mode, flipping this physical switch turned the lights on and off. In 3 way mode, switching it very quickly toggled the Nano Switch as expected. So, somehow the 2 3-way switches aren’t working properly with the S1 input.

One thing I noticed was that when this working 2-way switch is off, there is the expected 60v on S1. When the other 3-way configuration was off, there was only 30v on S1. Could this be indicative of something?

I’m actually a little concerned about those voltages. You should just have a straight 120v to ground, unless you have a floating ground. Are you sure the line (and neutral) in both boxes are part of the same circuit?

As far as the switch itself, supposedly it can sense a microsecond worth of state change. I need to sit down and look at this again…

So I mentioned earlier that the 2 lines were at least on different breakers in the same breaker box. I tried running the same Line to the other switch and running it back earlier in the 3-way configuration but that didn’t work, so I can try again with the 2-way configuration if it’s worthwhile.

Also to note about the voltages, with no wires in S1 and S2, there is ~64v on them when tested both against the neutral and the ground. So with a 2-way switch connected to the same local Line, that’s the same voltage that’s measured when the switch is off and the wire is connected. In the previous configuration with the Line coming from the other box, in the Off state the switches read ~32v.

I thought you were just speculating about the breaker - sorry about that. Which way to you have it wired now - the first way with wires on both traveler terminals or the 2nd way where one of the traveler terminals has nothing connected? The 2nd way is what we need to keep on one circuit.

I have to run out - I’ll take a closer look at this later and draw up a couple of diagrams.

Right now it’s back to the first way. I’ll swap back to the 2nd way when I get a chance.

OK, seems like it’s working after going back to the second way where I run 1 line to the second box with one of the existing travelers. Initially I got it working with 2 switches in 2-way mode. This was a little annoying, because the Nano Switch follows the physical switch. That is, if one of the physical switches changed from On to Off, the Nano Switch would go Off. If there’s a way to have this configuration but have the Nano Switch just toggle on any switch change, that would be ideal, as following the switches means sometimes you’ll need to flip the switches twice (if the lights were already off, and the switch that I walked to is currently in the on state, you need to flip it off then on).

I was about to stick with that setup, but realized having to double flip switches could get annoying. So using the same configuration, I just ran a jumper between the 2 traveler posts on the switches and put the Nano Switch into 3-way mode. This causes it to toggle every time a switch is flipped, which is great, except that sometimes it misses switch flips. It seems to work 80% of the time if I make sure to flip the switch quickly. If I just try to gently lift the switch, it’ll miss it most of the time. So with proper switch flipping technique, this is the most reliable way to not have to double flip the switches. But it seemed much more reliable in 2-way mode.

Thanks for working through this with me!

Just to sorta close the loop on this, here’s a diagram of what I was talking about in my “2nd” option above. The line comes in to the switch on the left and you put the nano switch in the gang box with the switch on the right.

So every time you flip the first switch (in gangbox 1), the voltage to terminal S1 should change between 120v and some other value.

When you flip the switch in gangbox 2, the same thing should happen except to S2 this time. The way this switch is supposed to work in 3-way mode is a state change on either of the 2 switches will toggle what’s coming from the OUT terminal. So that’s why you have to program both of them to be in 3-way mode.

Interestingly, what you did with your jumper is basically force it to only operate on the microsecond of time when the switch flips the common connection from one traveler to nothing to the other, since there will be a small lapse of time when the common terminal is connected to neither traveler. There may be a little bleed when you go slow which makes it not see that transition.

If you had it like this diagram and S1 and S2 programmed in 3-way mode, it should have worked perfectly. If it didn’t, there’s some wacky operation to this switch that I certainly don’t understand!

aeotec nano switch 3-way

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Did you make that diagram with some app made to show circuits? It’s really clear and easy to read.

That diagram is close. I used the Line and Neutral from Gangbox 2, running it back to one of the terminals on the switch in Gangbox 1. T1 and T2 are bridged on both switches.

So at the moment, it almost works perfectly. I feel like if I had the newer style paddle switches instead of 20 year old toggles, it would sense the transition properly every time.

It seems like the only way I can make it better at the moment would be if I could get the 2 switches back in a 3-way configuration and set S1 back to 2-way mode, but I only have 2 wires running between the 2 gangboxes and in that case they both need to be travelers. So I’ll probably just have to stick with what I have until someone from Aeotec chimes in to tell me the secret config to make S1 and S2 act as toggles in the 2-way mode.