I wonder if the following question should be considered off topic for this site:
When we talk DIY we are generally talking about residential applications. Sure the argument can be made too that small scale commercial problems can be considered part of that too, but Do It Yourself should primarily be a site about amateur and professional contractor Q&A residential and home improvement problems.
Sure we can say that in the question above, certainly some eastern European countries operate on three phase for residential, however the OP makes no effort to demonstrate a real problem that he/she is trying to solve. It is nothing more than a request for imformation that is more suitably found on Wikipedia.
We have a lot of really smart electrical guys in the community, but just because we may know the answer, does it really belong here?