Retractive/Momentary switch confusion (UK)

I’m interested in using some Hue smart bulbs along with some smart retractive switches to avoid them from being broken if someone turns of the lights from the mains switch. So after delving into this, thanks mostly to this forum, I gathered the best solution would be to use a Fibaro relay switch along with a retractive wall switch. So my questions are as follows:

  1. Do I need to use a Fibaro relay switch rather than Fibaro dimmer switch for the Hue bulbs to work? My concern is that I might not have the option to use a relay switch if my wiring is not a 3 wire setup with a neutral available. Right?
  2. How would the retractive wall switch behave if I turn off my Smartthings hub, the internet etc? Would the light switch be broken or still work as a dumb switch? Would I still be able to press the retractive switch once to turn on the lights, and a second time to turn off the lights; or is this only possible whilst the Fibaro z-wave relay switch is working with the Smartthings hub?

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.



Hopefully all of that helps clear up some of the confusion. :sunglasses:

And specifically, yes, the Fibaro relay requires a neutral and the Fibaro dimmer does not.

But if you use one of the battery powered options, then it doesn’t matter whether you have a neutral or not because you won’t have to wire the switch into the Mains. :sunglasses:

If you set everything up just right, using only stock DTHs For everything, and using only the official smart lighting feature to have the bulbs “mirror” The relay then you can probably set it up so that as long as the hub is working the switch would still work even if the Internet is down. But if the hub stops working, the switch would not work at all.

If you are willing to use zwave smart bulbs rather than hue smart bulbs, there are some Fibaro models which would allow you to have control from the switch over the smart bulbs even if the hub itself was not working. But you can’t use that with hue bulbs because they are zigbee, not Zwave.

There are some zigbee switches designed for operation with the hue bridge which could work even if the Internet was down and the smartthings hub was not working. Those are my personal favourite right now, regardless of which country you are in. They are discussed in the two FAQs above.

Thanks for the insight! I’m based in the UK and I was looking for a cleaner solution to the smart bulb situation than the wirefree switches. I exclusively use the app for controlling the bulbs myself, I just wanted to make sure that there’d be a way to gain control back if someone turned off the lights from the mains.

So my thought process was that if I rewired to a 3 wire setup and I use a retractive switch along with a fibaro switch relay, I’d be able to use IFTTT to flick the bulbs back on even if the switch is off. And given that it would be a retractive switch, the physical state of the switch would remain neutral regardless of what state the switch is actually at (ie on or off).

Am I wrong in thinking this? And if so, what exactly is the use of z-wave relay switches when dealing with smart lights?

On a side note, I was thinking of setting up the blinds in the room using the Somfy Sonesse 40 WT hard wired motor and placing the Fibaro Roller Shutter 3 in the wired switch so I’d have controller over it via the SmartThings hub if I wanted to control it remotely. I was thinking of using a 2 way retractive switch for this, such as:

Is this a viable option?

I’m afraid I’m not understanding what you are intending to do. From your description, the Fibaro would be cutting the power to the bulbs, which is precisely what we don’t want.

And you wouldn’t Use IFTTT, you would just use SmartThings. IFTTT is always cloud-based, and smartthings would at least give you the option of local operations.

So I’m just quite confused.

It sounds as though you haven’t had the opportunity yet to read the UK lighting FAQ that I linked to above. I suggest you start with the following post there:

@anon36505037 is in the UK and has now done two complete houses with Fibaro kit, so he could probably say more.

( i’m also not quite sure why you consider the Fibaro method a “cleaner“ method than the battery switches for control of smart bulbs. There are pluses and minuses to both, but the battery switches are both simpler and more foolproof. So I certainly wouldn’t consider them a “messier” option.

The main advantage to using a mains powered switch Is that it can also serve as a repeater for the rest of your zwave network. But it requires a much more complex approach both technically and in order to meet safety codes. )

Also, just to be very clear, Z wave devices like the Fibaro require a Zwave hub, like SmartThings or Hubitat. And the zwave frequency varies from region to region, so you must get one intended for use in the UK, not intended for use in the US.

You probably already knew that, but sometimes people find this forum just from a general google home automation search, not realizing that this forum is specific to people who have the Samsung smartthings home automation system. So they don’t realize that all of the questions and answers here are within that context. Most Devices discussed will need at least a SmartThings account and probably a smartthings hub.

Thanks for the insight; so I don’t really want to spend money on the additional bulbs; if there’s a cleaner and more cost viable solution; I’ll take it.

Basically my main aims for lighting are:

  1. Dim 2 warm (or at least some control with a tuneable white light)
  2. Individual control over the bulbs
  3. Hardwired controls that work like normal even if all things smart are removed.

So far as the grid switch goes; do you have any better recommendations? I’m looking for a matte black fit out for sockets and switches if possible.

There are some colour temperature changeable dumb bulbs which do work with regular dimmers to change colour temperature as they dim up or down, Philips makes one, their “warm glow” line.

There are also a very few smart white-only bulbs with the same behavior, notably from Osram:

I don’t know of any smart RGBW bulbs that do this, these typically run into the issues Robin mentions above. However, some very smart switches ( primarily the battery-operated ones) will also have the option of triggering preset “scenes” so you can have three or four presets which handle any combination of temperature and colour you want.

The Phillips hue dimmer switch, for example, is battery operated and can do both dimming and multiple scenes ( when used with the hue bridge) with multiple taps on the on button on the switch.

And some people choose to wallmount a tablet in order to get full control.

In these cases the usual approach is to put a child lock on the original switch and just leave it in place. Then mount the battery operated device or tablet near it. When you move out, you just remove the smart device, leaving the original as it always was.

Or you can cover the original switch (leaving it in place) with one of the faceplates made for this purpose:

The new “friends of hue“ switches are batteryfree, using kinetic energy from when you press the switch. These will work with the hue bridge in a fashion similar to the Hue dimming switch and Are much more stylish.

So these meets your 3 requirements, because the original switch is left in place so it will still be there once the smart devices are removed.

But the only devices I know of at present that meet all three of the requirements listed are either the battery operated ones or the batteryfree green energy ones. I don’t know of anything wired into the Mains that would work for all three conditions.

Why mains powered switches are different

The problem is that almost all mains powered switches when installed According to the manufacturer’s wiring diagrams (which is required by UK safety code) do cut power To the circuit branch that they are installed on. Which is not suitable for smart bulbs.

There are a few smart switches which offer a secondary control option, but the first tap/toggle Will always cut power. That means they do work the same as dumb switches, which is good if you are using dumb bulbs. But bad if you are using smart bulbs. :disappointed_relieved:

This is why all of the smart Bulb manufacturers, including Hue and Osram, Offer wall switches Which are not wired to the Mains. That sidesteps all of those safety code issues and allows you to have a wall switch which works very well with smart bulbs. (It’s also why they don’t offer switches which are wired to the mains.)

The US has different safety codes, which is why we will see a lot of forum discussion about other options from US members

In the US, in some jurisdictions it is legal to wire a switch to bypass control of the circuit branch, relying solely on the home automation system for Control of the lights.

Under the US national electrical code, you’re still supposed to follow the manufacturer’s wiring directions, so technically you are supposed to buy switches which are made specifically for this purpose, usually called “scene controllers.“ But unlike the U.K., in the US the national code is just recommendations, it’s up to each city to decide whether to make that local law or not or whether to modify it in anyway.

Anyway, the point is that in the US there are more mains powered options for control of smart bulbs, although many people still prefer to use the battery powered devices instead. They are simpler to install and generally offer more features. :sunglasses:

I hope that helps explain why there just aren’t very good options for mains power control of smart bulbs.

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Does anyone have a link to the law on a UK light switch. I was not under the impression the switch is a requirement.

Either way you have 2 options.

Just live with a stock white bulb that is dimmable and use a fibaro or similar to control a dumb light.

Use a hue or similar bulb which then requires the light switch to either be covered with a battery option (or kinetic) there are many cover solutions now and then the main switch will still work as per normal in an emergency if the cover is removed.

or rewire the switch to not control the light power. the smart switch will then just be used with an automation to turn on/off the switch like pressing abutton on your smart phone.

For the latter you can install the Micro switch in the rose/floor where there is neutral. the light rewired as a permanent spur so its not connected to the Live/switched live to the switch. and these used in to the microswitch to control it. as a smart only switch.

You can also rewire the switched live in the rose to neural and then install the microswitch in the wall (make sure you sleeve the switched live blue) and then its dumb in the wall switch but fully 3 wired.

@Behold81 I don’t think there is a requirement to have a working wired switch per se but there would be requirements covering the type and how a wired switch is fitted, how the wiring is fitted and how the light fitting is fitted. On top of that any electrical installation has to be at least approved by a certified electrician.

I would therefore advise consulting your local electrician.

UPDATE: Just seen this other post FAQ: 2019 UK options for light switches with smart bulbs? it confirms there is a requirement for lighting circuits to have a wired switch. Arguably leaving an existing wired switch in place but covering it meets this requirement.

As an example removing an existing wired switch and merely joining wires together is unlikely to meet requirements. However as you mention putting a cover over an existing wired switch so it cannot be turned off should be ok as the electrical side is unmodified.

I personally intend to do the following and will use a qualified electrician to do the wiring even if I do the ‘smart’ side of things.

  1. I intend to replace my current 2-wire circuits with 3-wire even if this may in most cases not be absolutely necessary
  2. I intend to use micro modules fitted in ceiling roses, unless by some miracle decent smart wired switches become available. Currently I am not happy with any existing wired smart switches for various reasons - not that there is a lot of choice in the UK :disappointed:
  3. Because of 2 above I would use momentary wired switches and these would in most cases be wired to enable on/off/dimming although perhaps in a few locations I may only implement on/off only
  4. For table lamps I will either use smart bulbs or ordinary dimmable bulbs with a plugin smart socket. Unlike ceiling/wall lights the odds are much lower that someone would switch off a skirting board level power socket and hence smart bulbs would be a lot more effective