Many overhead lines with double circuit are located in the highlands of Peru. The failure analysis caused by lightning in the Andean mountains is difficult to solve. A new electrical model for engineering failure analysis is proposed using distributed parameters, transitory analysis, combinatorial model and grounding system equivalent, besides an electrical equivalent for transmission line arrester for overhead lines and their constraints. This new proposal has been validated with a case study, it considers two overhead lines in parallel condition of nominal voltage 220 kV, and these overhead lines are critical for the operation of the Peruvian grid, with >600 km, shunt reactors and fixed serial capacitors installed in the middle point. >80% of the overhead line. The number of lightning discharges captured by the power transmission line and guard cables have an interesting behavior, in this analysis, a new expression of probability density function is proposed and a methodology for this installation. Finally the distribution of the currents and the shielding are required to improve the performance of grounding system and insulation, this model allows to avoid loss of function, transmission of electrical energy.