Electric vehicle presence is continually increasing following various incentives for environmental impact reduction. This increase will directly impact the distribution grids. The additional loading will result in a change in operating conditions. Both the voltage profile and the line loading will be affected requiring investments in grid reinforcement. Since charging stations can be activated in numerous combinations, it is important to detect the worst case in terms of grid impact. This paper presents a model for the worst-case analysis of charging station impact on the distribution grid. The presented model is validated on a representative case study.