A new approach to lightning transient studies including complex grounding grids is presented in this paper. The grounding system is modeled in Matlab/Simulink based on the transmission line theory. Using a bottom-up approach and considering the properties of the fundamental elements. a detailed view of measurement values will be presented and analyzed. https://www.nacrack.com/deal-alert-Dea-Eyewear-Jemma-deal-zone/