The lightning surges being considered the most dangerous events in power distribution systems, knowledge of the same allows to obtain a better selection and coordination of protection devices. Moreover, a better knowledge of lightning surges permits to optimize the location of device protection, to reduce the insulation costs of the installations, and to operate with risks of failure that are well known. The development of a computer application allowing determination of the optimal position of the surge arrester in power systems minimizes the risk of failure, thus permitting the selection of appropriate protection schemes for each network. As a consequence, protection costs are being reduced in accordance with the costs of the elements actually protected and the continuity of service to be achieved.