This! I have and documentation 
I literally have spare everything.
They also must be somewhat pre-configured/synchronized so it’s just a matter of exchanging components.
And check them regularly. Just found out that my spare maxcube (to control heating) is broken 
Meaning you wouldn’t want to run LEDs off a PoE device? My plan is to use cheap 10/100 Mode B passive power injectors like this one
I want to avoid running 2 cables to each location, but was planning on running PVC conduit as @papaPhiL suggests.
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We actually have two spare fridges. But the impact is much higher for us than just losing some food. My wife is T1 Diabetic. If we lose the fridge we lose her insulin. That’s another example about how only you can truly answer what poses the greatest risks. You will have unique impacts which can drastically change the calculation.
Have you looked into Last Will and Testament messages? MQTT may have this built in for you.
When an MQTT client connects to the MQTT broker, it registers a LWT message and topic. Then the broker keeps a heatbeat going between the client and itself. When the client stops responding, the broker will publish that LWT message to the LWT topic. Any client can subscribe to that topic and immediately know that the client is offline.
If you publish something like ONLINE as a retained message to the LWT topic when it connects to the broker and have the broker publish OFFLINE as a retained message to the LWT topic when the broker determines that it’s offline, anyone who subscribes to the LWT topic immediately knows whether or not the device is online or offline. And there is no need to implement any heartbeat logic yourself.
I’m no expert but I have read that it doesn’t work at all. You need some distance and/or isolation between data and power.
This. I bet there is more than one reader of this thread who got a flat tire only to discover that the spare was also flat.
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Regarding using wall panels, this has not really much to do with automation. Your automation will work with or without wall panels.
But there are situations were you would consider if its worth saving wall panels. Think about children, old persons etc… Those who do not want to or cant handle a smartphone the same way you can. If you have guests, friends or family visiting. Dont expect them to see your smarthome as smart as you do.
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Exactly. In theory the differential signaling should be able to filter out the noise, but I think a high frequency transient load like PWM dimmed LEDs might cause more noise than it can handle. That’s why that one never went past the “I’ve got a crazy idea” stage.
This is a specific topic, as in “disabled” access (disabled for whatever reasons), my argument would be, light switches would fail them too… in particular the joke of a switch common in AU.
That switch is 15mm2 (0.6" square)… my pads on the current panel are 25mm2 (1" square)… and can be modified to suit a difference audience. Also bearing in mind I will eventually use voice to control things.
I still believe some traditional form of ‘actuator’ needs to exist to cater for most… even if it is an abstraction on a touch panel.
I would have think about its feasibility and any code issues…
It certainly is a novel idea
[update] just checked the AU wiring rules, at least in AU it would violate code: “Separate cables are used for LV power and telecommunications.”
I settled on MQTT in a ‘heartbeat’ but certainly need to have a closer look at the protocol and your comment. Yes, I did implement a ‘heartbeat’ but if the functionality exists in the protocol, I will update my code. Thanks for pointing this out.
That seems to say they are outlawing PoE in the building code… I can’t see them doing that. Certainly you have PoE VoIP phones and such over there?
Well code I’m looking at Tasmota because of the ESP32 PHY support. I haven’t used Tasmota since I first started out with OH 3 years ago, but everyone is using it so it must be pretty stable.
Novel idea indeed, I am having to design the hardware myself. Obviously small batch for myself will not be so cheap per unit, but if there is more interest the cost would come down. If you have any suggestions please let me know. Once I have something to show I will share on here.
I don’t want to be a party pooper 
but DIY with a risk of burning the house down has the risk of loss of insurance attached to it… (topics discussed on this forum).
As for code, (I take it on the chin) I have mixed up LV with ELV, and am looking at these rules more closely in the next weeks.
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Yes, that is also on my mind. I will be doing lots of testing of these devices when I get to actually producing them.
I´m not sure I understand what you´re saying.
My point is, you can have all the automation. With or without wall switched. But there will be situations where ou might end up with a “fatal” situation. Lets create a simple example:
You have motion sensor for turning on a light when entering a room. (could be bathroom). You have disabled or removed the wall switch.
In case the automation fails, (the motion sensor fails, your logic fails etc), there will be no way to control the light if there is no manual wall switch.
If there is a wall switch, you can program it to overrule the automation (control the light, stop whatever timer you have running, turn on a monitoring LED telling you the automation has been switched off, send a push msg, you could even start a second timer, which will force a restart of the automation, and overrule the manual switch, after a few hours… Or just whatever you want).
The light will then be controlled manually from the wall switch, just as if there has never been any kind of smarthome/automation, no matter whatever happens “behind the scene” in your automation system. You could even pull the whole automation system (openhab) from the house, and the light will still be controlled manually.
This is, in my world, the way to make use of manual wall switches. Thats how I make use of them, even though I have automations and use voice control as well. If/when automation/openhab fails, I can still control my house.
If you decide to not use wall switches, you will probably end up in situations where you find your house no longer working at all or cant be controled, or as you mentioned, you´ll be forced to use something else, like a smartphone, tablet whatever, except if your light is not possible to control from these devices. In that case, you´re lost without the wall switch!. (just as well as your family, friends, kids, elders guests etc).
I would never go for a smarthome without some kind of “backup” controlling board/panel, which is useable for everyone. This is where a wall switch come in hand. You cant get it more simple and most often cheap as that. They may look silly and ugly on the wall. But they´re there for a reason, Make use of that in your smarthome.
Ofcouse if the wall switches is failing, then there is only one possible way to fix it, by replacing it. But in this particular situation you can probably live with the automation only for the short periode it would take to replace the wall switch…
You can live without the automation by the use of wall switchs. But most often you cant live without the wall switches, if/when the automation fails.
Its like having a backup disk failing. You main system is still running. Go get a new backup disk, and make the backup working again. If you wait too long or dont get a new backup disk, and you main system fails (which it will eventually), you´re screwed!
I´m sure you get the picture
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and I always have been thinking it’s only the Americans living in the past to keep deploying smart but still ugly switches to have a look like they were built in the 70s … but This! 
The difference to AU is probably just that some U.S. manufacturer got sued for this for discriminating the elderly.
I rephrased your sentence into a more generic theme, by using the term ‘disabled’ for any sort of impediment in context of the control, be it age, height, etc. For example: a kid is too small until it grows up to reach the light switch. An person trembling may have an issue hitting any switch.
In any case, I appreciate yours and any feedback
In essence, the degree of ‘safety’ or back-up is solely dependent on the risk appetite of the individual.
It was said that one may not find the candles or even the matches… well, in my case, we know exactly where the candles are, and the matches and the flashlight, and we find these in total darkness. Maybe it has something to do with my army past where a weapon is disassembled and assembled in total darkness, simulated by a shoebag over the head
What I do not seem to understand is the obsession for a backup. I am replacing one technology with another; like using a mobile phone instead of a landline. If the tower goes, I loose both anyway (I am on wireless Internet).
I am with you on augmenting existing systems, but where it is neither feasible nor sensible to stick with the old, I won’t. It seems like a first world problem to me, because we can, we keep the old stuff just in case.
The light switches are what started my automation journey. when I mapped out the electrical plans, I had 8 switches in the living/kitchen/dining area, which should have been controlled from three places. Forget eight cross overs, the mere fact I would have to remember what eight switches do killed the idea of physical light switches for me.
I’ve been working in offices which conform to the latest green and energy saving standards; the whole b!oody building, the most recent with 41 stories and 4,500 workers in it, has no light switch!
Again, I am not arguing; I “get your picture”, however, it is about personal risk perception and preferences… and the technology being used.
openHAB is stable enough for my to run my house on it w/o a blink… I am mindful of updates, and usually wait very long before I upgrade; and once my system is ‘production’ I may not upgrade again.
I have Raspberry Pis with uptimes of multiple years… one I actually forgot I had (a proxy, DNS and DHCP server). I am also in this computer business since 1980 (for what it is worth)…
I have a 100% uptime since 2014, despite the neighbours experiencing darkness for multiple days a year, and for two days in a row. The point I am trying to make is that hardware problems is not what I expect… and I do preventative maintenance; e.g. replace components on a set schedule, like SSDs every five years.
Lots of interesting comments here about reliability, switches and wall panels. Here’s my 2p about what I’ve found out so far.
I’ve been using OH for a few years now and have the luxury of a renovation where I ran CAT5e to all the light switches and cubbyholes for things. Lights all wired back to central located relays (no mains wiring at the switches).
Switches - we have pretty brass toggle switches which are wired in CAT5e as inputs to a board under the stairs (Mbed OS/MQTT). This means I can use some of the switches to control lights, and some for other things like audio which is nice. Still, these require OH and the lighting controller to be running, which is problematic when OH goes down or your controller crashes (yes, it’s DIY).
Beside each light switch I left a second back box (and cable) to be tentatively used for a wall controller, still haven’t found anything suitable yet. The light switches are so easy and tactile, but I need to add presence and temp measurement. It’s probably at the wrong height for a display too (1200mm from floor, current UK wiring regs) which I hadn’t thought about.
I’ve settled on using a used (£30) 10/100 Cisco PoE switch and cheap PoE splitters to power the whole lot - it’s reliable and I can use the PoE switch to turn stuff on/off remotely. I should probably buy an identical PoE switch for backup…
Reliability - the network is super reliable, mosquitto (MQTT) has also never gone down. I had problems with InfluxDB/Grafana taking down OH, so OH and mosquitto are now on a separate industrial SBC which is rock solid.
I seem to have problems when rules and bindings fail, when I’m working on configs, or things don’t recover boot/properly after a power loss (frequent when re-wiring).
Lighting is essential for safety - that’s why commercial buildings are required to have emergency battery-backed lighting. I don’t want those in our house, but have realised the system does need to degrade to more reliable methods, eg: OH dies -> MQTT light switches still control lights directly -> network down -> hard wired backup light switches for essential lights only in an easy to access cupboard.
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Or just use a base system that simply doesn’t fall over?
… or wait for the next lightning strike…
I think the only system that qualifies for it “does not fall over” is the traditional mains wired switch-light-combo. Anything else might be highly reliable, it may last 20 plus years, but once there are electrolyte capacitors are in there, there is no way it lasts as long as the simple traditional combo.
However, it does not mean there are not systems, which provide a high level of reliability. Twenty years is good enough for me, given the ‘comfort’ and automation I can achieve with it.
Thinking about my reply to Kim’s post, it made it very clear to me, that I will not install traditional light switches.
There a many ways of increasing the reliability of systems; e.g. spares, back-ups, etc.
… and there are always trade-offs; let’s not forget these. We make these every day; e.g. love a sports car, but am carting a family around; if there is only money for one, guess which one it will be?!
I still feel there is an over-emphasis on ligh switches, when people use, at the same time, LEDs, which are prone to failing. For example, in my LED trial, three out of ten brand (and approved) LEDs failed prematurely, while all Chinese (eBay) LEDs are still going. Conclude what you want, but my point is: LEDs fail; and once there is a variety of those installed, people usually do not keep spares. Hence, weather the light switch fails or not, the ‘light’ will be dead until fixed.
… something that is easy to implement with one cable feeding all in parallel from a battery; e.g. one 3W on the ceiling in every room would do. I am thinking about it…
Maybe having a (grid-backed-up) off-grid system makes me less worried about light switches. Just to add, I am self-reliant on fresh, grey and black water and electricity. As for reliability: my inverter/charger shows the remaining life of the capacitor bank in percent, which will be replaced once it nears “100% used”.
I have to admit, it was a struggle to clarify the light switch topic for me, but thanks to all your feedback, clarity, at least for me has set in for good.
nice! looks like a small novation launchpad
True 
didn’t know them, but a quick search showed me how similar they look.
I based mine on the Adafruit Trellis