Electric Power Systems (EPS) are composed by two interdependent infrastructures: Electric Infrastructure (EI) and its Information-Technology based Control System (ITCS), which controls and manages EI. In this paper we address the interdependency analysis in EPS focusing on the cyber interdependencies between ITCS and EI, aiming to evaluate their impact on blackouts-related indicators. The obtained results contribute to better understand the EPS vulnerabilities, and are expected to provide useful guidelines towards enhanced design choices for EPS protection at architectural level.