The 22.9 kV vacuum interrupter (VI) built-in load bus switcher (LBS), which is most often used as a load switch for distribution, extinguishes the arc that occurs during normal load opening and closing and fault current interruption within the VI housing to quickly switch circuits. As a protective device for contact separation, the rated current is supplied in a normal state. When a fault current flows due to a fault or an accident in the power system, the contact is disconnected in a vacuum state to block the fault current. In this study, in order to design the optimal VI, the heat dissipation characteristics of VI according to the center electrode distance 0/1/2/3 cm were analyzed by applying the finite element method, and the results were reflected to improve the structure of the VI.