An accidental disconnection of power supply for operating theatres may result in fatal accidents. Thus, it is necessary to import the electric safety system in medical locations. This paper shows an analysis of simulation for the safety in medical IT system based on KS C IEC 60364-7-710(Electrical Installations of Buildings - Requirements for special installations or locations - Medical locations). The analysis was progressed by measuring leakage currents according to variation of volts, circuits and loads. And it was made database for calculation the reasonable length of branch circuit.