This paper presents the development and validation of a real-time hybrid simulation (RTHS) system for efficient dynamic testing of high voltage electrical vertical-break disconnect switches. The RTHS system consists of the computational model of the support structure, the physical model of the insulator post, a small shaking table, a state-of-the-art controller, a data acquisition system and a digital signal processor. Explicit Newmark method is adopted for the numerical integration of the governing equations of motion of the hybrid structure, which consists of an insulator post (experimental substructure) and a spring-mass-dashpot system representing the support structure (analytical substructure). Two of the unique features of the developed RTHS system are the application of an efficient feed-forward error compensation scheme and the ability to use integration time steps as small as 1 ms. After the development stage, proper implementation of the algorithm and robustness of the measurements used in the calculations are verified. The developed RTHS system is further validated by comparing the RTHS test results with those from a conventional shaking table test. A companion paper presents and discusses a parametric study for a variety of geometrical and material configurations of these switches using the developed RTHS system. Copyright © 2013 John Wiley & Sons, Ltd.