L Lightning is one of the unpredictable natural phenomena, and cannot be avoided. The purpose of this study is to evaluate the lightning rod system (SPP) that has been installed and determine the effectiveness of the lightning rod in Building S. Especially for areas with moderate or high rainfall, one must be vigilant and anticipate the risks that may occur if lightning strikes. Therefore, the risk of damage due to lightning strikes must be minimized, so it is important to install a good lightning rod installation. To provide a better level of protection, the amount of ground resistance is determined based on the function of the building. An external lightning protection system provides protection to the building from direct lightning strikes, and one of the most important components of this system is the air termination. To determine the position of the air termination, 2 methods were used, namely the mesh method and the rolling ball method and also resulted in the addition of the number of finials on the center side of the building or the addition of the finial height on the corner side of the building. It is hoped that after this research, the building manager can consider the existing conditions and add everything that needs to be evaluated so that the lightning protection system in the Trisakti University S building can work optimally.