With this thesis my goal was to introduce the steps of a building’s electrical network’s design and the related theoretical background. The relevant knowledge of Hungarian and international standards is essential, therefore, in my thesis I tried to include these standards. I discussed in detail the purchase of electricity from medium and low voltage network. Then I discussed the topic of shock protection, covering in particular the presentation of the various classes of shock protection and touched the topic of EMC. After that I discussed the various problems, primarily the overvoltage and the protection against it. Then I described the importance of reactive power compensation and introduced a method for it. I also touched the effects of various harmonics occurring on the network. Then I showed how a building’s electricity network design takes place in theory. Finally, in this paper I discuss using the theoretical knowledge in a particular building, a pizzeria in Szolnok which electrical network I designed.