Fibaro Dimmer Backbox Depth

I’m looking to start adding some smart switches to my HA setup, and have only read good things here about the Fibaro Dimmer 2. However, I note that in the installation instructions (from the Fibaro website) they recommend a minimum backbox depth of 60mm! I haven’t seen this mentioned anywhere else, and I can’t find a supplier of anything beyond 47mm so I was hoping to get some wisdom from in here!

Any thoughts?

You might be able to fit it into a 47mm box, just… I think there are a few options:

  1. Cut out part of the back of the box and make it deeper (though not sure about fire regs on this it would fee a quick and easy solution).
  2. Try taking the box off and putting the fibaro behind the box, with only the cables from it going through the hikes in your box. Another fairly easy solution but may be limited friending on how the back box is installed, and also make sure you support the cables somehow, you don’t want them sliding down the inside of the wall.
  3. I’ve moved to installing in the ceiling since I don’t very neutrals by the switch and gives me much more space to work with.

As Robin says, it depends on the switch. It’s also worth noting that it can be dodgy fitting anything deeper than 35mm into some internal walls in older houses as you risk damaging whatever’s on the other side.

I have a newer extension with 47mm backboxes, but the majority of my house is fitted with 35mm and all contain dimmer 2 modules just fine. You certainly couldn’t go any less than that though.

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I had the same issue with box depth in parts of my house. This solved the problem. Initially I tried putting the module at the ceiling rose but then got interference issues that sometimes caused a double bounce when the switches are activated. Move module to the switch and tat went away.

Are they stackable?

I’ve used a number of these around the house. I’m not sure how people manage without them to be honest. Hardly any space even in the deepest backboxes once you factor in the switch gear and the amount of extra wires two way switches have.

Not tried to stack them. I found 1 was enough for all but the slimmest back box. I have MK Logic plus around the house so they actually look OK. For sure not as good as without, but needs must.

Can you post a link to the MK spacer? I looked for a while and could not find an MK one.

Thanks for the replies, everyone! :slight_smile:

My concern is around heat dissipation. If they’re quoting a 60mm minimum depth (for 1!) and we go with 47mm, then have an electrical fire, Fibaro will be covered, and we’ll probably find that we’ve contravened all kinds of UK wiring regulations! I’m starting to think that the MiHome range from Energenie might be a better bet - in spite of the additional cost of a second smart hub.



How does the LightwaveRF range compare to MiHome - especially when used with SmartThings?


Unfortunately it’s stateless but you can integrate it into ST using IFTTT.
I have also integrated a Raspberry Pi into the mix.
So, ST turns on the Lightwave RF switch/outlet, this goes through the cloud to the Pi which used UDP to talk to the Lightwave RF hub via the local lan.
Works a treat and there isn’t much lag.
The light switches are dimmers and they have slave switches so that you can use for a hallway with 2 light switches.
I like the design too.
BTW I am in no way connected to LWRF I just like there product.

I have a (qualified) electrician installing a few Dimmer 2s and Bypasses as we speak. As @anon36505037 said, if you have a good electrician install it, and sign it off, there should be no issues.

I’ve also tried the Mi|Home setup and wasn’t too impressed. Needed always on internet connection, cheap materials, not much customisation. Having said that, that was over a year ago… A lot may have changed.