After giving initial answers to the questions about the system functions I marked all cable ending on the house project. I described where the wall switches, electric, ethernet and tv sockets should be. I defined which circuits should work independently and which can be grouped. As a result I had a project, which – even though was very unprofessional – was sufficient for the electric company to make the installation:
All wires powering the groups of sockets and lights were supposed to end in the basement where the steering unit was planned. The thickness of the wires was set according to the expected future load. In case of the steering wires – those which run to the wall-mounted switches – I decided to use a standard 4x2 Ethernet cable. I was lured by the number of wires (4 pairs! So many extension possibilities) and the low price. Consequently in every junction box prepared for the wall switches there was a ‘computer’ wire, which gave me no option but to make an ‘intelligent’ installation. Without a central controller, there would be no possibility to turn the lights on…
Why have a decided to make a ‘star’ structure, i.e. an installation where all wires from the switches and sockets run directly to the controller? I felt it was more universal, I knew it would fit to any PLC controller and would work with any wall switches without the necessity to address/identify them. I also expected to be faster. One system I had seen before, which was based on the loop infrastructure and the inputs were identified by chips, had a significant, annoying lag. I also think that the ‘star’ structure is safer – cutting of any of the wires does not have impact on the functioning of the others. Can the price be an argument? I do not know. In 2008 I bought the 4x2 wire for EUR 0.1/m. Is it more than the future price of the input id units?