This paper studies and assesses the performance of a 230kV transmission line when subjected to lightning strikes using the unconventional technique of Underbuilt Wire (UBW), of overvoltage reduction in the insulator strings. The results obtained in this study demonstrate that transmission lines with UBW significantly reduce the energy absorbed by surge arresters, especially for soils with high resistivity. With reductions of up to 70,83%, the energy absorbed by surge arresters of lines that have UBW has a better performance.