Hello,
we are about to build a house (new building) and I am thinking a lot about smarthome.
The most obvious would be KNX, but that is also a question of cost and I also like to tinker
I would therefore be interested in your opinion on the following idea:
One small control cabinet per floor, where the power cables are connected as a star network and are mostly connected to relays. Parallel to this, I lay a low-voltage network to the (light) switches and other sockets for signaling (similar to KNX, but not as a BUS). At first I thought about 5V, but I was told that there would be problems with external voltage, etc. So it would probably end up with 12/24V.
The switch signals only control the relays at the beginning and thatâs it. So much for the new building and the doing for the electrician.
Why the whole thing: I have the possibility to hang an esp32 or similar in between with minimal effort and make the whole thing âsmartâ with ESPHome (step by step).
What do you think? Interesting or the wrong path? Is there a smarter option? How would you go about it?
Thanks for the constructive feedback
First ideas:
PCF8574 I2C 8CH optocoupler for button detection (10âŹ)
8CH SSR or MOSFET boards (preferably with I2C) to control the relays with 12/24V (30âŹ). However, I have not yet found any suitable boards for thisâŚ
You are not very clear about your wanted wiring⌠If power, do current/voltage drop calculations between your voltage, current, wire diameter and length.
If signal, higher voltage is better for interferences but itâs giving you a big hassle to connect to low voltage MCUs. If you are willing to go with esp32, take care of your signals with wifi, ble, and short shielded 3v3 wiring.
If youâre already planning to run LAN cables through the house, you can use PoE (Power over Ethernet) to get DC power to any of those LAN points. I believe the standard voltage for PoE is 48v, and you could step down from there.
EDIT: I think there are ESP modules that support PoE, so youâd be killing two birds with one stone. Youâll have power for the device, as well as hard-wired communication, which will always beat WiFi.
Thatâs what they were telling 25 years ago, during first boom of internet and concept of iot. We were installing ethernet all over the houses with an idea that tomorrow every fridge and laundry machine is online with ethernet. Every room also had telephone jack and pre wiring for alarm systems.
It never happened. Everything went wireless.Because itâs more convenient and because 99% of old houses didnât have all those wirings, so it was missing the mass adoption.
By the way, think of all the loads that we have in our houses nowadays. All electronics use DC, led lightning use DC, new motors are DC, new air conditioners are DC, resistive loads donât care if itâs AC or DC. Iâm sure that I have hundreds of AC/DC converters in my house
For efficiency we should have DC in our houses instead of AC. But itâs not gonna happen (any time soon).
I would draw an utp cable with every power cable to every power socket, switch⌠Doing that you have multiple options: you can use only power cable and connect old way ( disregarding utp or using it later when needed), you can use POE, you can use it for 12/24V system (if you choose to use it), you can use it to trigger relays directly⌠just make sure to install deep âwall baseâ so youâll be able to squeeze a module inside, behind a switch/socket.
5V is a no-go, thatâs for sure. Youâd get only 3-4V at the end of longer cable. Higher voltage = lower current = less loss in cables.
Then you use these switching PSU modules at the end for 12/24V, or these ones for POE step-down.
karosum: actually signaling, i.e. tapping button signals, possibly also temperature, humidity, movement.
The esp should then also control the 230v relays (but would then be 12v/24v control voltage).
Ideally, I can then also operate an esp with the mains.
vincen: ok, that means it should be 24v⌠I think knx uses it tooâŚ
dzerovibe: yes, Iâve already seen some, but they only drew power via poe, everything else continued to run via ble/WiFi
karosum: I agree with you, it definitely wonât work without WiFi, but I would like to do without battery-powered iot devices wherever possible⌠I donât think itâs sustainable or ecological, and as I hope to have the opportunity to build a new home soon, I want to cover as many cases as possibleâŚ
Iâve also read in an article that DC grids for the home would be much more effective nowadays, but the different voltages are a massive problem.
protoncek pavel: so you would lay 3 utp cables in a room with 2 light-switches? 2 to the switches, one for the LAN?
Thank you for the tips
(Sorry I couldnât link you, because of forum restrictions)
How could that be the problem? At the moment we have different voltages from 120/240/400V to 3V but from AC to DC.
Problem is complexity of change, old devices not being compatible. So may be year 2100.
Anyway, to build specific wiring for future, for my experience, is going to be mistake. Build what you need now and install big/extra conduits wherever you can.
Yes, one utp togehter with each power cable where you plan to install switch, power outlet etc⌠So you can first install totally classic âdumbâ lights/power outlets/switches, but later when you decide to add smart system to any electric device, you already have utp there waiting, and you just add esp module.
Lay power cables normally to where fuses will be, while you lay all utpâs to a place where youâll have your router, switch, poe, internet, server⌠letâs say âserver roomâ
Having all utpâs in one place (like server room) has a lot of benefits - for one you can later program VLANâs, etc⌠just donât forget ot mark them
Oh⌠perhaps itâ would be better to use ftp (shielded) cable, since they will go beside power cables.
