Necessary information for making decisions regarding installation of LSA in a double circuit 400 kV line running between substation Vyborgskaya in Russia and substations Yullikyalya and Kyumi in Finland are discussed. Lightning discharge energy requirements for LSA have been calculated and the risk for single- and double-circuit lightning related faults with and without arresters has been estimated as a function of tower footing resistance. The decisions regarding ultimate number and location of arresters along the line are described and the type and technical data of the arresters selected are given. Furthermore the measuring system used to monitor lightning surges through the arresters is presented as well as the experience from the installation and the 3 years of service.