Using fibaro 212 dimmer - help

I am looking at using the fibaro dimmer 2 (212) for the control of the majority of lighting circuits in our house. I have one ready to try out, and Im going to start with a single switch. We have had the house rewired in the last 18 months, but as this type of home automation wasnt in my mind at that point, Im almost convinced that none of the circuits will have a neutral available at the switch.

I have a few questions for those who have done this:

Am I correct in believing that these dimmers can be used as simple on/off switches for non dimmable circuits? (ive read about relays either requiring a neutral, or being welded open by the inrush current for LEDs)

As I have LED lighting and the majority of (if not all) rooms have less than 50W per circuit load, I believe I am looking at a dimmer bypass for each circuit. However, I have seen a comment in here that if a neutral is available then a bypass may not be needed (though no wiring diagrams Ive seen seem to suggest this is the case).

For circuits where there the back boxes arent deep enough to accomodate the module, Im hoping to install in ceiling. Does anyone know where I can find a diagram similar to the ones from vesternet for ceiling installation of the 212 module? I can only find ceiling installation for the 211.

As it appears possible to use these in a ceiling installation rather than at the switch, when I get round to adding one of these modules to the 2 and 3 way switched lighting, would ceiling installation for these be possible, rather than trying to find room in a crowded back box? (Im guessing not as access to the permanent live would be required, and thats more than likely not going to be at the ceiling rose or first downlight on the run)

Also, Ive read a long thread about how to set up the 212 on ST, however Im unsure of the settings needed to make it operate as an on/off rather than a dimmer.

Any help on the above would be much appreciated. Im hoping to be an active contributor once I figure out these basics. Im fairly competent with most stuff, but this is my first forray into light automation (other than basic on off of an outlet to a table lamp). The IFTTT, maker, autoremote, sonos stuff Im fine tinkering with - but just like a second opinion before I go messing with the 240v stuff outside of the standard wiring diagrams provided.

In short, I can install exactly as per the diagrams showing installed at the wall, but in my case thats going to probably involve chopping out to deepen the boxes, and an ear bashing from the missus when I have to repaint round all the switches (because the decorator handily blended them all in). :unamused:

Is there an easier and more SWMBO friendly way of installing these? :confused:

Many thanks for any help, it is greatly appreciated.

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Before you start anything, why not setup a test wiring set on your desk to experiment? You can also use that for inclusion of your dimmer to hub later, to include the dimmer after installation will be difficult if it’s too far from the hub.

Yes, you can use it as simple on/off switch.

You can (with the use of a custom device handler, which I would strongly advise anyway) set the Dimmer 2 parameters so that it is on/off only. This removes all dimming functionality including soft on/off.

If you have a neutral, you will never need a bypass 2.

If you have no neutral and <50w draw, you may need a bypass 2. It’s worth trying without first, and if you see any strange behavior, a bypass 2 should rectify it. The Dimmer 2 is not a relay, and always has some current going to it. The bypass 2 just absorbs any current before it goes to the light.

Ceiling installation isn’t all that straightforward. You will either end up with a light that can only be controlled by smarts (and not at the switch, unless it’s a smart switch) or you will have to run switch wires back to the box. I would try to avoid this if at all possible.

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Thanks for the replies.

I did contemplate the test route, and after reading about making it easier to include, thats convinced me it is what I should be doing.

I had a quick look behind one of the light switches just now - as suspected, no neutral :unamused:

I’ve got a board, several spare switches and light fittings, so I reckon rather than jumping in with both feet, Ill set the test board up instead and see where I get.

Im not looking forward to getting the things into the backboxes of some of the lighting circuits. The one Im really not looking forward to is two three gang switches, all six of which are controlling three way switched circuits. :fearful:

Where can I find details on running a custom device handler? I found a guide to installation of the 212 with custom code on this forum (but cant for the life of me now find the thread again), is there some sort of definitive code/device type setup we should be using for using the 212 as an on/off?


Many thanks for any help.

Are you in the UK?
If so you will/should have a live, neutral and all your wall switched live’s appearing in the ceiling rose.
You will then be able to control your lights via the wall switches and via ST.
As someone has already said, check and amend the parameters according to your setup.

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Yep, Im in the UK.

If there is a handy diagram somewhere that shows what I should be able to find in the ceiling and getting these working there, that would be a massive help.

As soon as Ive proved the concept of being able to automate the more complex circuits in the house, and with minimal upset of “er’ indoors” (read, dont damage the decorating round the light switches). I can go ahead and place my order with vesternet for all the kit I think Ill need.

I do however think that the amount of automated devices/circuits needed in the house will be N+1. Where N is the number of automated items I currently have.

The Vesternet Web site does have lots of wiring diagrams on it.
Have a search there.

Ive been searching there, but no joy on a 212 ceiling installation, though there is one for the 211.

Ive posted elsewhere though that the diagrams have been pretty helpful, and enough to convince me to buy the stuff from there, as they seem to take an interest in the products they are shifting.

Try this

Yep, I’d gone through those - and follwed the
link to this one which shows ceiling installations about half way down -
but it is for a 211. Not a 212.

Im now looking at the wiring differences for a 211 and 212 to see if
the 212 can be fitted in the ceiling rather than at the switch for each
installation. This will save me a lot of issues with cramped back boxes
and solid wall installations.

So. Mixed results.

I set up my test bed. A simple switch, light bulb and associated wiring to mimick a two wire switch, no neutral at the switch.

I set the dimmer 2 up as per the wiring guide on vesternet and added a customer device based on the code from rajiv posted here:

At first after the device had been discovered as a fibaro dimmer, I didn’t realise that I had to set it in ide as the newly created fibaro dimmer 2 UK.

After doing this, the device eventually behaved. I could switch it on using the switch and using the smartthings app.

So, I decided to unplug my test bed and move it to a location where I could test while seated and reading the forum for further information.

However when powered back up in its new location the light did not work.

When first plugged in it cycles from off to full brightness twice, then a third time but much slower. Then it goes off. When I try turning it on from the switch, it turns on (full brightness) then goes off after a second. Same action when turning on from the app. Status goes to “turning on”, briefly shows as “on”, then goes “off”.

Does exactly he same when I now move it back to the test location near the hub.

I’m concerned that I’ve just mimicked a power cut, and what happened was apparently the dimmer going screwy and not reverting to how it should.

Any ideas?

I’m nowhere near giving up, but I must say I’m disappointed that there isn’t a simple setup for a lightswitch, and it involves the use of custom code to get a basic device close to working with smartthings. It’s not filling a newbie with confidence that smartthings actually care about sorting the basics in the UK.

I’m fairly sure I’m correct in saying that there is a difference between the 211 and 212 for ceiling installation :

The 211 allowed a switch signal to be sent over the live wire, meaning that you could keep a switch on the wall. This feature is not present on the 212, which would require switch wires running back to the module for a physical switch.

I’m not sure why the feature was removed, possibly reliability or to meet an EU safety requirement.

As an update, I’ve now wired my test rig with a neutral to the dimmer. Now works just fine.

I’ve read that with a two way setup, you can only have 85% on the load/lamp.

I tried setting max to 75% in the parameters but still no go. Lamp lights then goes out.

As soon as I’ve switched to the wiring with neutral to the dimmer, no problems.

It appears that either I’m missing something, or using this in a two wire setup just isn’t going to work.

I’ve found 212 in ceiling wiring diagrams from fibaro themselves, so it should be possible, depending on what wires await to be found behind my ceiling roses.

Whether I’ll be able to do that for the spotlights I don’t know, as I have no idea where I’ll find the ceiling rose equivalent for those.

Heres a summary to date. Possibly a long post, but hopefully it may help me get to the bottom of the problem, and also serve as information for others who could run into the same problem.

Right now, Im holding off purchasing any more fibaro items, as I simply can’t prove this will work in a UK standard installation with no neutral in the switch.

My test bed consists of:

Mains in
toggle switch
fibaro 212 dimmer
60W lamp

Code being used for the 212 relay is from Rajiv (rmbhatia) and can be found here:

The following parameters are set:

parameter 20 - set to 1. Enable dimmer to work with toggle switch
parameter 26 - set to 1 S2 can control dimer as well
parameter 32 - set to 1 this sets on off mode (0=dimmer, 1= on/off)
parameter 35 - set to 2 this sets auto configuration after each power on

Here is the test bed set up as required if there is no neutral in the switch (switched live only). Permanent live into L, poles of the switch wired to S1 and Sx, Bridge between N and Sx, Output wire to lamp. The neutral is striaght to the light.

In this setup, once power is applied the device runs through its initial calibration. The lamp increases in brightness to around 70% from what I can guess, then turns off. It does this twice. It then steadily increases in brightness again much more slowly until it reaches what I assume is 100% then turns off.

After this has completed, if you toggle the switch, or turn on with the ST app, the light comes on for about one second then goes off. The LED turns red on the rear of the dimmer for a few seconds. The status is correctly identified in the app (on for a second then off again). The lamp does not appear to go to 100% brightness. Id say the 70% max it gets to during the first two warm ups in calibration.

Here is the test rig with a neutral supplied:

Live to L, poles of switch to S1 and Sx, Neutral to N and the output to the lamp.

In this setup, after running through the same initial setup/auto calibration, the device functions as expected. Light on via the app, off by the switch, vice versa. Status updated in the app etc. All works fine.

Ive had a couple of the ceiling roses off in a couple of rooms to check whats available - no permanent live, just the switched live. Admittedly these are in two wardrobe rooms upstairs, and accessing the wiring for these in the loft would not be that much of an issue. However if the same is true downstairs, then Im left with no alternative but to use the two wire switched live setup - which appears simply not to work.

Any suggestions from the community on this one? Im open to suggestions as to why is my test rig not working in scenario one above?

I think you should talk to Fibaro on this. It should work, and is intended to work like this. I’m glad you set up this rig, as it’s quite enlightening(!)

I have experienced similar problems with some of my modules, but they have been easily overcome. I had assumed it was an overcurrent issue as the total wattage exceeded 250 in my case, so I reduced max brightness, and gave the soft-on a couple of seconds more to fire. In a non-dimming scenario this wouldn’t be possible.

I have a feeling that you might have more luck in this setup with a lower powered light. Just a feeling.

As for the 212 in the ceiling, you’d need to hook up your live/switched live in the box so that your ceiling then had a permanent live. Then take a switched live from the Fibaro and feed that to the lights. As I said in an above post, this does render the conventional switch useless. In this case you could look to a ‘Popp’ style smart switch to replace it.

I was really hoping that the two wire system would work. If only because this provides easier future access to the module should I need it. (Im thinking if the smart system goes down for whatever reason, its easy enough to pop the switch open and remove the module to get the lights back to a simple manual setup)

However as I have lots of solid walls, there may be a bit of chopping out in the backboxes required. So in this regard ceiling installation would be a lot less messy. And, according to my yests at least, using its own permanent live and neutral will yeild better results.

However, it appears that my light wiring must be using junction boxes, not “that” much of a problem in the upstairs rooms, as loft access is possible, albeit a pain as the house has three separate lofts.

However downstairs, if the junction boxes are not that easily accessible, or when I inspect the ceiling roses downstairs they dont have the right wires, Im in a bit of a pickle.

It is quite annoying that Fibaro market these as working with a two wire system, yet out of the box on a simple rig like this, they just don’t.

Searching on fibaros own forums, Im not the only one to see this behaviour with the 212. Again the discusion then goes into altering settings, manually overriding max brightness settings in the parameters etc. etc… And still the problem persists.

If you have to go altering paramaters that are set by the auto calibration, then that tells me the auto calibration isn’t doing its job properly.

Tonight Im going to try the device in a live scenario, powering a lower power LED light (though unfortunately I dont have the dimmer bypass yet - delivery tomorrow on that). I shall see how that works out.

As for installation in ceiling, if all the wires are there, it should be straight forward with the 212, just move the wires around on the rose and set up as below - I believe this is correct…

If Id have found this when I opened up the ceiling roses, Id have ordered about 40 of these dimmers today, but until its proven working Im going to hold off.

Would you believe, the first switch I take off the wall in the new build part of the house has live and neutral in the back box :joy:

Bit of a squeeze getting these in the back box though! Even with a 45mm. It’s not having it. Looks like I’m punching the back out.


Well that’s good news at least!

The 211 might be good to look at, I don’t know much about it, but I’ve heard that it’s possible to send a signal over the permanent live in a ceiling rose situation which keeps your switch present.

I personally went for low power filament GU10s (dimmable) all round, knocked back boxes out to 45mm at least, and put 212s behind every box in house. LEDs don’t quite do it for me yet, and anything other than the switch box would have been a compromise.

Went for a two way switched light next. Again found neutrals in the switch, got it kind of working.

It’s working from the app and from one of the switches. So my list of probable causes is:

A - that I haven’t altered the wiring at the second switch and there is still a live to it rather than it switching just the two wires from the first switch.

B - the device has not taken up the latest parameters that I set in the device handler. I removed it and respect added the device and set the handler to the one where I enabled control of the dimmer with S2 as well.

Is there a guide on forcing a device to update it’s parameters?

A user friendly way of viewing these per device would be very useful.

Have a look at my post. I had the switch off after a second problem and the settings in my post below kind of cured it.
If I press too quickly the light doesn’t come on, but if I give it a good solid press then it comes on and stays on. It takes a while to dim up to being on but at least it stays on.