Electromagnetic interference effects of transmission lines upon nearby communication lines are real problems, especially in faulty cases. The paper presents the effect of high voltage transmission lines on communication lines by using the Electromagnetic Transients Program (EMTP) to simulate the high voltage transmission lines and the communication lines in different configurations and in different faulty cases. The software is used to study the effects of various parameters, such as separation distance, and different cases of short circuits, current magnitude, and the screening factor.