We need to start from the beginning on this, because there may still be some confusion. You may already know all this, but I just want to make sure we’re all talking about the same thing
1) The switch should not cut current to the bulb
The basic rule for smart bulbs is never have the switch cut the current to the bulb. It doesn’t matter whether it’s a toggle switch, a rocker switch, or a momentary switch.
If the switch cuts the current to the bulb it’s a problem. And the momentary switches that you were describing, including the Fibaro relay in most configurations, will cut the power to the bulb.
That said, there are many switches which can be wired in such a way that the switch no longer controls power to the bulb. Or you can use a battery powered switch. So instead of turning the bulb off By cutting the current to it, the switch sends a radio message either to the hub or to the bulb itself that tells the bulb to get brighter or darker.
That way the bulb is always on power and the radio inside the bulb can always hear the next command, and you protect the bulb from the problems of inrush current that occur when power is cut and then restored.
Again, the switch form doesn’t matter. It can be a toggle or a rocker or momentary switch. As long as it is not cutting the current.
2) The country you are in determines the device options you will have because the safety codes differ
Now we come to a tricky bit. In the US, in most places the safety code will allow you to put in a “dummy switch” which replaces the existing switch and only uses radio in most places in the home (except the attic).
But in the UK, you typically have to have at least one mains powered switch for each circuit branch. You can add additional dummy switches to a room, but not have only dummy switches. And I believe the rules are different yet again for a staircase. But I’m not by any means an expert on the UK safety codes, so if you are not in the US, you should be sure to check with someone who knows more.
In most countries, you’re fine as long as you leave the Mains powered original switch in place and then you can either put a little box over the top of it and put a battery powered dummy switch on top of that. Or you can put a child safety lock on the original switch and put the dummy switch wherever you want it to be. Or you could have one original switch and just tell people not to use it and then add more dummy switches. (Again, except maybe for staircases in the UK)
So there are a lot of options, you just have to be aware of all that.
3) Using a Fibaro option
If you’re in the US, you probably would not use the Fibaro option because there are other better device choices available. You would just use a dummy switch even if you wanted it to be Mains powered.
The Fibaro comes up in conversations about UK installations, If there’s already an original Mains powered switch in the room, you can use the Fibaro to create a second dummy switch.
Or, probably more commonly, you could have a Fibaro that is capable of doing two different things Setup so that one switch controlled dumb lights in the ceiling rose, and a second switch controlled smart bulbs in table lamps or something like that. So that the second switch is not actually cutting power to the bulbs.
Whether all of that will work for you depends on the exact details of what you’re trying to do, but it’s usually the context that these discussions come up in.
We’ll talk more about this in a little bit.
4) what happens if the hub is not working or the Internet is out?
This depends on the exact details of what your setup is. It is possible to set up switches that can still control smart bulbs even if the Internet is down or even if your hub is not working. But you have to plan for that in advance.
If you are using a smart switch/micro to control dumb bulbs, then normally if your hub is not working the switch will continue to work exactly like a dumb switch. You won’t have any automations, but you can still turn the lights on and off from the switch.
If you are using a smart switch to control smart bulbs and your hub is not working, Then there are some specific devices which can still be made to work, but it depends on the exact model numbers and the exact set up.
So typically in planning you need to decide what you want the behavior to be and then include that as one of your device selection criteria.
Just as an example, when we were talking above about having a mains powered switch in the room and then having a dummy switch as an auxiliary, a lot of people won’t worry about having the auxiliary switch switch always work, if it doesn’t work they’ll just use the master switch. Then there are some specific devices which can still be made to work, but it depends on the exact model numbers and the exact set up.
So typically in planning you need to decide what you want the behavior to be and then include that as one of your device selection criteria.
Just as an example, when we were talking above about having a mains powered switch in the room and then having a dummy Switch as an auxiliary, a lot of people won’t worry about having the auxiliary switch switch always work, if it doesn’t work they’ll just use the master switch. But if the dummy switch is the only one in the room or the primary one, then you will want to plan differently.
5) so what devices should I pick?
It’s going to depend on the exact details of what you want to do. However, this is a very frequently asked question and fortunately we do have two different community FAQs for this, one for the US and one for the UK, which should answer the question. If after reading this post and reading the appropriate FAQ you still want help figuring out just what you should do in your own house, then start a thread under projects and people will be glad to give you individualized advice.
US FAQ
UK FAQ
Hopefully all of that helps clear up some of the confusion. 