908MHz has a wavelength of roughly 13" and if all wired Z-Wave devices are repeaters, in theory, having two devices within 6.5" of each other would be a detriment to RF communications, especially when sandwiched together. I think that while looking at a 4 gang electrical box that needs 4 Z-Wave switches.
Has anyone else put much thought into that and/or have experienced communications issues with that type of installation?
I have a number of three gang boxes with three zwave devices in them, and never had any issues.
Not arguing whether there could be issues or not, just anecdotally that I haven't had any.
I have a 5 gang box with 5 Zwave switches in it.
Are you concerned about the antennas having mutual coupling?
Or are you concerned about receiver dynamic range?
It might be interesting to note that the Zwave 'path' from the nearby HE C7 hub to these 5 switches is not the same! Three of the five are 'direct' and the others are 1 level away, and none of those by their proximal-located switches.
I have two triple gang boxes about a foot apart. One box has three Inovelli Red switches and the other has three GE switches (two switch, one fan). They have been solid for a couple of years.
The only time I had an issue is when something was leaning up against one of the switches. It was holding the paddle down and flooding the network. 
Near Field antenna performance is essentially black magic. So, if you chant the correct spell when installing, you'll probably be just fine!
Like others, I have 3 Zwave + devices in quad gang boxes, and while I've seen some perplexing routing in some cases, I've never noted any issues.
S
I was curious about RF interference with one device transmitting over the other on the same frequency. I hear you on the weird routing sometimes.
That's good to know. I was looking at the second-generation inovelli red switches, but they are all out of stock and they don't know when they will be getting more. I really like the notification features of the LEDs. This is a reply from Inovelli yesterday:
Unfortunately, we don't currently have an expected date to restock Red Series switches as we navigate the supply chain delays and computer chip shortages. We are hoping to get restocked in the new year but don't have any confirmed production runs from the factory.
So now I'm thinking about going with Aeotec illumino switches and using Inovelli Red dimmers, which are still available, at the locations were a visual notification is most desirable. The Aeotec illumino switches also happen to be 700 series devices were the Inovelli's are not.
Sometimes you have to hold your jaw just right during installation for things to work out perfectly. LOL
I have no experience with those (probably fine, just no personal experience), but just as an FYI here is another zwave 700 option that's in stock and a bit cheaper:
Thank you!
Yeah it really stinks. I want to replace the GE switches with Inovelli but I can’t.
Yeah... Sounding like they won't have stock until well into 2022 at this point (6 more months?). Sucks for them and their customers.
If interested, you can set up the Inovelli dimmers to work like on off switches by changing the dim speed.
I like the inovelli red dimmers but the toggle feels flimsy. I wish the inovelli rockers felt like the GE's. I've also noticed the radio seems weaker on the inovelli than the GE's. I have a lot of 3 gang and four gang boxes and haven't noticed any issues with them other that with all the wiring, it's pretty cramped. The signal seems fine and I don't have any route failover.
The paddles don’t bother me because I rarely use them. I only use them occasionally to manually set a scene or override the default automation.
The only reason I’m replacing the GE switches is because you can’t uncouple the relay from local control. I’ll reuse them in other, less important, areas.
I use the innovelli for the same reason, I also like the RGB bar for changing color based on alarm armed/arming/disarmed status. Keeps the wife from tripping the alarm when she lets the dog out or whatever.
I have 2 zoos zen72 dimmers in a 3 gang box. Middle and right switch are then zen72s. No problems.
I have several 3 and 4 gang boxes around the house.. no issues to report. 
The only concern I've had in the past is possible heat issues with so many electrical devices confined in one space + plastic gang boxes... but have never really encountered this in the wild. Newer smart switches with their lower profiles seem much better at mitigating this.
Inovelli mentions something about the heat in their little install books based on how many heat-sink tabs you break off and what the switch is capable of handling load wise. 400 watts with all 6 of the tabs, 300 watts with only 3 tabs on either side, or 200 watts with all 6 tabs removed.
This is yet another (possible but maybe rare) issue that the average consumer/enthusiast wanting to get into HA might not realize is even a thing..
The only reason I knew of this was early on a skeptical (of HA switches not named Lutron) electrician brought it up to me. We had to go through and make sure everything was okay in the various multi-gang boxes. Fortunately all was good..
As I mentioned it has gotten better with the slimmer switch profiles and most likely (in general) people won't have any issues BUT it's something to think about if having inexplicable and random weird mesh issues.. and a good note to always read the fine manual before installation...
Download the Hubitat app
