Thanks @TheHundredthIdiot
i have two more questions that i’d be grateful if you help me with.
for a 3 gang dimmer switch, would i need 3 of these samotec sm309 modules?
and if i use these, and i turn off the physical switch, would i still be able to use the hue app to turn on the lights? or do the physical switches have to remain on always?
Yep you would need 1 per gang for independent switching with a large back box - at least a deep 2 gang size I’d say for 3 devices…
Depends how you wire these up, you can remove the physical switch completely, physically switch the live feed to the module, or wire a physical switch to control the module alongside Hue - think that needs a capacitive or momentary press switch though(?).
You can get the instructions from the Samotec web site which detail wiring options. Probably worth making sure you are OK with installing or getting a qualified electrician to check over before purchasing…
Always better to be sure 
thanks!
I’ve just been told by samotech that the SM309 is not compatible with rotary dimmers…
are you not using yours with rotary dimmers?
I am not using rotary dimmers just straight switches in the power feed. I ‘think’ capacitive/momentary switching can dim, ie. Hold/touch to dim but not 100% sure without checking…
Again all in the instructions if I remember correctly
thanks, i’ve definitely checked the manual but can’t find any reference to how to connect rotary dimmers. not sure what you mean by capacitive/momentary. if it wasn’t clear already i have no idea about electrics!
thanks for your help
Basically either a push and hold to make (momentary) switch or a touch sensitive touch to make (capacitive) switch… I believe these will work by default or, with factory setting, a normal on/off switch too.
I have not looked into this at all beyond casting my eyes over the manual when I wired mine up. As I said previously I do not use manual switching so can’t really comment with authority or from experience.
If you are unsure about wiring I really would get an electrician involved if I were you - very nasty things electrical faults/fires…
i have just seen this option: 2-gang kit: Zigbee Rotary Dimmer for dimmable LED / Halogen / incandescent bulbs. (No Neutral required) – Candeo
it comes in single gang or 2 gang varieties.
Can i replace a 2 gang dumb rotary dimmer with one of these? so that my dumb bulbs become smart?
if so, will i be able to control the lights via the app even when this zigbee rotary dimmer is in the off position?
obviously i will consult an electrician once i can confirm the above.
Yes - that’s exactly right.
The Candeo rotary dimmers are an excellent way to make dumb circuits smart, without changing the bulbs/LEDs.
Yes - You can turn on the lights from Smartthings even when the lights were turned off using the physical switches.
amazing! this is exactly what i need then!
I just purchased this:
It paired easily and, despite generic warnings I had read that Smartthings may not see all three gangs, it did.
I sent it back for two reasons, one, it needs a really, really deep backbox (basic 2mm finger plates under the switch are nowwhere near enough enough) and I couldn’t be bothered bashing into my wall to deepen the exisiting hole, and two, because I wanted a switch which can work in detached mode (normal light switch mode is that power is automatically set to the light when the switch is clicked, no rules or automations needed - detached mode means that a routine needs to be created to tell the switch what to do when it is clicked).
@smartn00b @JDRoberts @TheHundredthIdiot
As JDRoberts may remember, I have been looking for smart lighting solutions for a long time but have at my own choice set much tougher criteria. However I have more recently found something that does meet these in nearly all aspects and may therefore be more than suitable for you.
Firstly several Z-Wave micro-modules would work particularly Fibaro and Aeotec spring to mind. These can do dimming, can do 2-way aka staircase circuits and can support 3-way momentary wired switches. They however CANNOT be used with Apple Home so I reject all Z-Wave devices. (We will ignore the fact that you need to get the right radio frequency for your region, we will also ignore the fact that Smartthings no longer directly support Fibaro.)
Sadly all the wired decent dimmer switches like Lutron Caseta are US only.
I have looked over the years at various Zigbee modules and initially a problem was not being exposed to Apple Home, but since Philips upgraded their Hue Bridge to add Matter support this is no longer an issue. What has still been a problem is that Samotech, Candeo, etc., etc. did not support momentary wired wall switches or 2-way staircase circuits - or at least stated this when I asked them. Frustratingly all the Chinese brands like Tuya only do switches/relays and do not do any dimmers as of yet.
A lot more recently however I came across the following brand.
This definitely works with momentary wired wall switches and 2-way staircase style circuits. It also works with the Philips Hue Bridge and is exposed to Apple Home. Via Matter from the Phillips Hue Bridge it is also exposed to a Smartthings Hub. I have tested one of these modules connected to all three at the same time with complete success.
I tested it with a single Philips non-Hue dimmable LED candle filament bulb which you might expect being such a low load would suffer the infamous flickering issue at minimum dim level but I had no such problem. This is however I would regard as a premium LED bulb brand. Enkin like many/most smart dimmer manufacturers including Fibaro and Aeotec do make a matching ‘bypass’ module for this sort of issue but as mentioned I found no need for it. As a tip, the Enkin module does let you set a minimum dim level on the module. I found this most useful to ensure that when I used an app or the wired momentary switch that dimming down to minimum did leave the bulb illuminated faintly. If you allow the bulb to dim beyond that i.e. to zero then you cannot tell if it is on and dimmed to zero, or off. This results in a short press not turning the bulb off and on but turning off and on to zero with no obvious effect.
Note: It can be used from the Hue Bridge in Apple Home via HomeKit or Matter depending on what you set. I tested both but I am sticking to Matter.
So from the dimming perspective this has proven to be that elusive beast - a Unicorn 
and ticked all my boxes 
. 
I now just need a matching switch/relay equivalent.
PS. The Enkin module says it does not need a Neutral wire. I was testing it in a standalone manner and emulating what would have normally been in the wall.
I’m using a yagusmart but I’m fed up with it and want to replace it. It has a tendency to go offline every month or two and needs the fuse pulled in the box to reset it.
I need something that fits in a shallow back box, the yagusmart one squeezes in and it’s 24mm deep, so I need something similar or shallower.
Basically I want
1 back of switch is 24mm or less deep
2 zigbee or thread or matter Wi-Fi, not a zwave.
3 2 gang
4 very reliable, this is for a kitchen so gets heavy usage
5 must work with SmartThings for automations with movement sensors
6 no neutral wire needed
7 preferably no capacitor needed
I’d been hoping a matter switch would arrive that would fit the bill but I’ve been waiting and not found anything yet. Anyone found anything that ticks all those boxes 