In this paper on the basis of the electromagnetic field theory, the magnetic induction and flux linkages outside and inside tubular conductors are obtained from the Ampere Loop Theorem, and then the formulas to calculate approximately the reactance of tubular busbars with a. In this paper on the basis of the electromagnetic field theory, the magnetic induction and flux linkages outside and inside tubular conductors are obtained from the Ampere Loop Theorem, and then the formulas to calculate approximately the reactance of tubular busbars with a. The quantitative study of this problem has to be based on establishing equivalent circuits of main wiring, when there rarely are formulas to calculate the reactance of tubular busbars. Assuming that current i flows in a circuit, after. The busbar sizing calculator determines the required busbar dimensions based on the continuous current rating, short circuit withstand, and thermal limits for switchgear assemblies. The current rating is calculated from the conductor cross-sectional area, material (copper or aluminium), and maximum. Ge, Qun, Li, Zaiqiang, Liu, Siyuan, Xing, Jiaqi (2023) Formulas calculating the reactance of tubular busbars and their derivation in primary electrical connection schemes. Scientific Reports, 13 (1) doi:10.