I found a 389 page document titled "Electrical installation guide" from Schneider on their Polish server.
http://217.153.88.147/Poradniki_guides/Electrical_installation_guide.pdf

It contains a lot of information about electrical installations, with focus on the 230/400V system. Someone might find it useful as reference or design guide.

Very interesting! But this aint Polish

C-H,
That's a rather comprehensive document and well worth the time taken to download it.
I haven't had the time to fully read the thing yet, but from what I've seen of it,
It should be a good read.
Will get back to you on this one.

C-H,
I've had a chance to read through the document and there is some really good information in there, especially regarding the design of HV distribution systems and Earthing.
Also TN,TT IT sytems of supply are covered as well.
When I was looking through the document, I couldn't help but think that it was written by a crowd of Equipment Manufacturers, as there are various references to TeleMechnique and Merlin-Gerin in the text.
But, there are some really good charts and formulae in the document, especially where Motor calculations and Power Factor Correction are concerned.
Thanks for that one, mate!, this will more than likely come in handy, to me in the near future.