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i'd like to create a map of my house on which i can control the lights. ( Currently there are no extra cables etc to enable domotica in the house).

Meaning that behind each light switch button i'll need some IOT which connects to my "main" pannel which i'm thinking to go for a raspberry pi.

Currently i was thinking about putting up a relay with a ESP8266 Wifi-module + a transfo to convert 220v to 3v3v.

ex: Relay: https://www.reichelt.com/be/nl/ontwikkelaarsboard-relais-module-2-kanaals-5-v-debo-relais-2ch-p242810.html?&trstct=lsbght_sldr::239148

Wifi-Module: https://www.reichelt.com/be/nl/experimenteerbord-esp8266-wifi-module-soldeerbaar-debo-esp8266-12f-p236022.html?&trstct=pos_5 Ofcourse i want it to be as small as possible to be able to get it after the light switch.

ex. transfo: https://www.banggood.com/AC-DC-Isolated-AC-110V-220V-To-DC-3_3V-800mA-Constant-Voltage-Switch-Power-Supply-Converter-Module-p-1114202.html?rmmds=buy&cur_warehouse=CN

My main purpose is to program the whole project (MQTT protocol) and in time expand it to see costs of electricity etc. as this has no time limit i do not mind asking an electrician to help me out installing the electric components to be sure nothing goes wrong on the hardware side.

This will be tested with a external lamp/switch first of course.

As my knowledge is limited about the recommended hardware i'm not sure that above componnents are the best way to go?

I know best case scenario everything is controlled with PCL's but i do not think we have a neutral cable running to each switch ( i'll check this this evening and update this thread).

  • You can replace the switches by smart buttons that send a signal to the home panel that then sends a signal to switch the light. That way you can redesignate the switched live to neutral to power switch. – ratchet freak Feb 12 at 9:59
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    If you don’t have a neutral, how are you planning to connect the 220v -> 3.3v transformer? 3.3v doesn’t transport well long distances due to voltage drop, so I doubt remote transformers solve this. Have you looked at commercially available products? I’m assuming you’re in the UK? Location is important as there are different rules that must be followed based on your location. – Tyson Feb 12 at 11:59
  • Hi @Tyson I live in belgium, i have looked at some smart i have looked at some for example: amazon.com/WeMo-Enabled-Control-Anywhere-Compatible/dp/… but they do not come with 3 way switch handling; also at first glance the cost would be a lot higher and i wouldn't be able to make the software myself. ( correct me if i miss something). As for the transformer i was unaware that the neutral cable was required to do this. – Wouter Dumon Feb 12 at 14:46
  • Note that particular product is "Sold by and ships from Amazon.com". That is most likely a quality product that has been tested and listed by a reputable testing lab. A listing that says "Sold by someone other than Amazon here and ships from Amazon", then it is the Amazon Marketplace. It is the same firehose of unsafe, cheap Cheese junk seen on eBay and Alibaba. Except not "cheap" anymore... – Harper Feb 12 at 17:48
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What you're proposing is to make using prefab electronic modules.

That's fine to play with in the lab. But if you want to actually install that in a real house in the EU, you're going to need to take your assembled, finished equipment over to TUV and have them certify it as safe for use in houses. Which ain't gonna happen with components from a place called "banggood" lol...

If you do not have your equipment certified, any malfunction which causes fire or injury will create severe personal liability.

Anyway, design questions go over to the Electronics Stack Exchange. Our wheelhouse here is accomplishing your goals using pre-built technologies to homes. To that end...

First, you should not need to add wires to your home. Using low-voltage wires to control loads throws back to the GE RR7 system, which used 24VAC to operate relays. Technology is, if anything, reducing wire count. For instance, if you have a 3-way circuit where the spur switch only has switched-hot and 2 travelers, and you want a power receptacle there on the existing wires, Smart switches are how you get that done.

Any reasonable solution will involve

  • powerline signaling, which itself harkens back to 1975 and the X10 system, a reasonably "open" standard. And/or
  • wireless communication, which no doubt started a week after WiFi chips were prototyped.

For instance, Insteon uses both adaptively. Powerline signaling is not 100% reliable in the US because every home is fed from 2 transformer phases (opposed, so we dall them poles), so half your circuits have a transformer winding between the other half. Less of an issue in Europe.

You don't need to stick something behind the mechanical switch; not least, there isn't room. The smart device should replace the switch and provide a reasonable human UI.

Switch loops (power fed into lamp, hot and switched-hot only to the switch) are a special case. In that case, a module could be fit at the lamp, the swich loop converted to always-hot and neutral that powers the smart switch, which communicates with the module.

You won't have to design any of this. The marketplace is thick with appropriate products, and getting thicker.

Keep in mind also that such alterations will affect the resale value of the home. Commercially rated smart switches will be appreciated, homebrew jobs will need to be torn out and restored to legal standard before sale.

  • I know you know this but in the US a home is fed from 2 legs from a single phase that is split. – Ed Beal Feb 12 at 21:28
  • Hi @Harper thanks for the clarification, the fire safety went completely over my head and which is why i will abondom any idea about building the electronics myself. i'll look more into products like Insteon to get the job done. The project price will pump up a bit but like you told, the house value will go up aswell. Thanks for the usefull insight in this! – Wouter Dumon Feb 13 at 8:36

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