This paper describes algorithm for computing the resulting current reduction factor of multi-cable connection between two power substations. The algorithm is based on the originally developed analytical expression. The connection consists of arbitrary number of power cables and earthing conductors buried in the same trench.In the mathematical model, metallic sheaths of the cables and earthing conductors make set of passive conductors of the multi-cable connection, while the phase conductors of the power cables are active conductors. The procedure is applicable to the evaluation of shielding effectiveness and to protection problem arising from power faults.