for my first experience with the raspberry pi 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 will be the raspberry pi with the touchscreen ( tablet like form).

Currently i was thinking about putting up a relay with a ESP8266 Wifi-module connected to it.

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.

Now to the questions :)

  • Will the socket relays be able to draw power from the light wires which go into the relay
  • with just those 2 components will the ESP be able to publish the lights status and set it on/off no matter the status of the physical light switch In other words does there need to be an voltage detector added to be able to tell the components the light is on/off. With this i mean will it be possible to see if the light is turned on or off on an application

  • Will the physical light switch still work?

  • Are the listed components suited for the job? ( as they will be in a narrow space in the wall).
  • Something i do not find a lot of info about: Won't they multiply my electricity bill as it will be 24/7 online?

This build will require an 220v to 3.3v converter as well; ex.: 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.

  • This is a bad idea to DIY. You are running face first into electrical codes and you will likely hurt yourself or someone else if you continue with a naive approach. – crasic Feb 12 '19 at 1:43
  • the answers are (1)maybe, (2)unanswerable ... no idea what it is asking, (3)probably, (4)if you have to ask, then no, (5)it will add slightly to the bill for sure, it may multiply the bill if something goes wrong when you go on a vacation and all the lights turn on – jsotola Feb 12 '19 at 2:39
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    240V AC can KILL if it doesn't kill it can BURN YOUR HOUSE DOWN". If you have to ask this you are not competent to do this. – Dougie Feb 12 '19 at 7:18
  • Hi, I would try this external first ofcourse with a little lamp and see if i don't fry anything :). if i understand it correctly i'll need an transfo (banggood.com/…) between the electricity of the wall to the components. As my main intention is the programming part and not the hardware part i come here to ask for help about the hardware that's required. I do not mind asking a electrician to help me set up the first switch to help me out there – Wouter Dumon Feb 12 '19 at 8:24

short answer: no

WARNING: This is potentially very dangerous!

long answer: you will need a way to power the electronics plus the wifi module you have selcted may need a breakout board. You may also find that there is no neutral wire behind the switch plate. The switch would still work depending how you wire the relay. Running costs are very low.

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