We take such simple things around the home for granted - like being able to turn lights on / off, opening gates, etc. But not everyone can do this.
I am considering making a type of home automation system for a chair bound non-mobile friend, and my thinking is as follows :
using a central PC to run a microcontroller board linked to a PC to control items around the home ( lighting, alarm system, gate automation, etc ).
The microcontroller is linked to a central PC and I have the basic design for a PC program to allow the user to easily switch things on / off, open / close / set timers, control emergency lighting during power outages, etc.
The question I have relates to the correct way of controlling items on the home electrical circuit, like lighting.
My thoughts are to re-wire the light switch (1 click on / 1 click off type of switch ) to a small enclosed PC board in the ceiling and change it to 12vDC which will be supplied from the central control PC point ( already has a decent UPS, so 12vDC freely available in existing wiring around the house ). The ceiling based PC board will contain a 12v relay which will be capably of powering the light for the room ( say 220v 60W ). This will allow the PC to also control the light by turning the relay on / off.
In addition to this, a small laptop or netbook (mobile connected to the persons chair) would have a wireless connection to the central PC, allowing the same program to be used "on the move".
Would wiring the lights, or any other appliance on the home circuit, and controlling these with 12vDC powered relays, be breaking any laws or creating hazardous situations ?