It is briefly described electricity grid and transmission of electricity over long distances. Transmission lines are part of the transmission system of electricity over long distances, and this paper shows the process of designing transmission lines and main components of the system which must be taken into account (climatic conditions, transmission poles, foundations, conductors, protective ropes, non-conductors, suspension and jointing equipment and grounding). Based on experience working on electrical installation of high-voltage transmission lines, electrical installation of transmission lines is shown by stages (reinforcement of transmission poles, conductors, setting intermediate spacers.). On the example of the project of building the transmission line Kosovo – Albania (Pristina - Tirana) will be shown the potential problems that appear in the construction of transmission lines.