One of the main problems with distance protection of tapped lines is related to zero sequence infeed from an earthed tap-transformer. For the solution of this problem the distance measuring units algorithms for the tapped lines are developed. The new earth-faults distance protection algorithms are based on the use of numerical optimization methods and the objective function adaptation of to the network configurations. The estimations of new and classical algorithms operation in different earth fault conditions at the end of first protective zone are obtained. It is shown that the effectiveness of the developed earth-fault distance protection algorithms operation during different fault conditions on the tapped lines are higher then effectiveness of the classic algorithms.