Fibaro dimmer 2 and 2D compact lamp?

(hyeung) #1


I have a standard single one way toggle switch that controls an external light. The external light is a 16w 2D Compact Fluorescent (4 pin) lamp much like -

At the back of the light switch, I believe it’s 3 wire system Setup as a loop at light switch. So have 3 sets of wires (each set with live, neutral n earth), one from previous light, the next light and to the switch itself. The switch itself has a N loop point for the neutrals.

Anyways, I’m interested in getting a Zwave light module to control this single one way light switch.
Was looking at the new fibaro dimmer module below (FIBEFGD-212)

Question is, does anyone know if this module would be suitable for my setup as described I.e the external 16w 2D Compact Fluorescent lamp?
Btw I dont need dimming, just happy for it to be on/off via the existing toggle switch.
Just concerned if there would be any comptiability issues with compact fluorescent lamps etc?

Any help/tips would be greatly appreciated!

(Robin) #2

The dimmer 2 will work fine with a CF, and using a 3 wire connection you won’t need a bypass module either.

You’ll need to change a few device parameters so the dimmer knows to work in on/off mode and that it’s connected to a toggle switch (it wants momentary switches by default).

Parameter changes are easily done in the device handler though.

You may find the Fibaro Single Switch is more appropriate for this application, but I would probably still go for the dimmer 2 as it leaves doors open for future changes / repurposing + costs the same.

(hyeung) #3

Thanks Robin!

Was initially planning on the single switch relay…but realised the dimmer2 could potentially be more Flexiable if required at a later date.

What’s the story with this bypass? When is this required? And what’s it’s purpose?

With regards to device handlers n smart apps…can you direct me to the latest n greatest handler for the dimmer2?

Thanks again…

(Robin) #4

Having just looked again, it’s quite possible you will require a dimmer 2 bypass module for CF’s… even on a 3 wire setup.

Your best bet is to try without and if you see any flicker or glowing when off add the bypass.

Best handler is:

This DH allows you to take advantage of the second switch input for changing scenes etc.

(hyeung) #5

Thanks Robin…

Will it do any damage if you don’t have such bypass module? So you saying it’s a side effect of CF lights? Such that they still appear to be partially on when switched off?

Does one wire the dimmer module any differently when adding such a bypass module?
Can you wire the bypass module behind the switch like you do with the dimmer module?

Like the idea of the scene functionality. I assume one quickly switches off and on to trigger this second switch in order to activate the configured scene? Something along those lines?? Pressume all the scene association is done via the smart app?


(Robin) #6

The bypass has to be wired across the load:

As you are on a 3 wire setup it can go behind the switch bridging between Neutral and switched live, but most people would put it behind the light itself.

I understand what the bypass does in a 2-wire setup (see below) but I’ll be honest and say I don’t fully understand what the bypass does for a 3 wire setup, but the manual clearly says that it’s required for LED’s and CF’s even in 3 wire setups.

That said, It won’t do any harm in a 3-wire setup to try without a bypass first. I have a set of CF’s running without a bypass, but they total a much greater wattage than your individual 16A lamp. The manual warns against powering up without a bypass for 2-wire setup, but there is no similar warning about 3-wire jobs.

In a 2 wire setup (without neutral), the dimmer has to power itself by trickling power through the load. Bulbs like LED’s and CF’s (that only need a tiny amount of current) tend to glow slightly as a result. The bypass diverts the trickle though itself, thus avoiding unwanted power going through the bulb.

The bypass also softens the flashing effect caused by trailing / leading edge dimming technology which, unlike older rheostats, abruptly cuts off the start / end of each sine wave as part of the dimming method.

In regards to switches, the Dimmer 2 works best with momentary switches (but makes less of a difference for you as you’re not planning to use any dimming functions)

You can connect 2 switches to each Dinmer 2 module:

S1 - controls the load (and also sends scene ID’s)

S2 - sends scene ID’s

Using @hajar’s device handler, the various scene ID’s pop up in the ST activity logs, and apps like CoRE can see this and use them to trigger pre-programmed actions.

(hyeung) #7

Thanks for that information! I’m afraid I didn’t follow the details of the bypass? :frowning:
Attached is some pictures showing our typical setup behind the switch. I understand the wiring is looped at the switch via the N Loop & Com connections on the switch. Based upon your wiring diagram, I’m trying to figure out how this translates to my setup on this toggle switch?

Can you or anyone else help give this a look to advise I’m on this correct track in wiring?
I’ve also detailed the bypass module, which I’ve wired behind the toggle switch, again hope someone can confirm this looks correct?

Also, based on the backbox shown. Can you advise that the dimmer module will fit along with the bypass module??

I had planned to utilise some wago connector plugs to loop the neutrals and likewise the lives together. So presume my switch will only now have L1 and COM connections whilst NLoop will be left blank.

Appreciate any feedback on all this? Hoping I’ve got the illustrated wiring correct for this Fibaro dimmer on my given setup?


(Robin) #8

Your wiring diagram is spot on… you don’t need to connect anything to the ‘N Loop’ terminal on the switch but it also won’t harm to leave the Neutrals connected there as existing.

The ‘N Loop’ does not actually connect to anything inside the switch (unless the switch has a neon?), it’s just there to facilitate bunching those wires together without needing a wago.

I think you will just squeeze it all in the box. Worst case scenario you’ll just need to put the bypass behind the light.

You could also just tuck the bypass behind the plasterboard above the switch (looks like an accessible void there if you loosen off the back box). Just keep all wire terminals inside the back box.

If you get a two gang switch you can take advantage of S2 on the dimmer 2.

(Robin) #9

I can’t really explain it any better… but you can try your setup without the bypass first.

If the CF glows or flickers when turned off, you’ll need the bypass.

(I’ll fix a few grammatical typos above though, which may make it easier to read lol… was obviously typing too fast the other night!!)

(hyeung) #10


One last thing I forgot to ask…in order to run the bypass module over the relevant live and neutral wires. How’s does one identify which of the live and neutral set of wires that runs to the lamp?

Base on the picture of the wiring behind the switch…I assume I would be right to say that the brown wire that’s currently connected to L1 would be regarded as the live that runs to the Lamp (load wire), and therefore be connected to the output terminal of the dimmer module?

I assume to identify the corresponding neutral, I would just do a continuity test between the above live and each of the 3 neutrals? Once Ive got a complete circuit then I know I’ve got the correct neutral pair to that live…allowing me to then install the bypass over this neutral and live pair.


(Robin) #11

All the Neutrals are the same and connected… you can just connect into the Neutral Wago or ‘N Loop’.

Single brown going to L1 is correct.

(hyeung) #12

Thanks for your sound advice on this stuff!
I just need to buy the bits now and get cracking :wink:

Just out of interest, I have a light fixture that’s got 8 x g9 halogen bulbs rated at 40w per bulb. So giving a max rating of 320w which is well over the spec of the dimmer module.

However, If I was to just swap out all the bulbs for 28w that would give a total of 224w.
I assume in this case I would be fine and safe to wire and use this type of dimmer module without issue? Stupid question but just wanna check :slight_smile:


(Robin) #13

Yes… reduce to below 250w

Most people upgrade to LED in that situation… saves money in the long run.

(hyeung) #14

Cheers Robin…
I think the leds in these size were either very large, expensive and not very bright at the time we looked…?

But will certainly check again. I guess the bypass will be mandatory for any led setup.


(Robin) #15

Not necessarily, the LED spot lights in my bathroom total about 75W, I have them on a 3 wire setup with no bypass. Works fine.

On 2 wire you nearly always need it… best to try and see with 3 wires.

(hyeung) #16


Got all the parts and successfully wired everything up as per the diagram.
Have a 1 gang 1 way toggle switch wired up. Also managed to get scene activation working via 2x click action. All good!

However, I’m interested in having a 2 gang setup. Such that the first switch will behave as is (control the lamp) and the second switch will do various scene activations to trigger other actions on table lamps etc I.e. Switch 2 - on, off and 2x click. And the first switch will control the
I have a 2 gang 2 way switch, but wanted to check how to wire appropriately?

The 2 gang 2 way as follows
Switch1 - Com L1 L2
Switch2 - Com L1 L2

So do I connect Fibaro Dimmer as follows
Switch1 Com to Dimmer SX; and Dimmer S1 to Switch1 L1
Switch2 L1 to Dimmer S2

Advice please?

(Robin) #17

Sx to com on both switches.
S1 to L1(1)
S2 to L1(2)

Will work better with momentary switches.

(hyeung) #18

Thanks will give it a try on the 2 gang 2 way.

The hager switches I have only appear to do single rectractive ones.
No double retractive or 3 position retractive.

(hyeung) #19

Btw do I need to config any additional parameters other than setting up as toggle switch and scene activation?

(Robin) #20

Correct, just set as toggle and turn on scene.