To provide a power feed connection device wherein only a current flowing through a conductor through which an overcurrent flows is cut off and currents flowing through other conductors through which no overcurrent has flows are continuously carried as they are, and provide its method to use.

This device is provided with: an insulating case part 12 wherein multiple pairs of insertion holes 18 into each pair of which an pair of insertion pieces of a plug are inserted are formed; a couple of positive and negative wires 24 introduced into the case part 12 from a power source 22 outside the case part 12; multiple pairs of conductors 20 which are arranged inside the insertion holes 18 of the case part 12, fitted and electrically connected to the tips of the insertion pieces when the insertion pieces are inserted into the insertion holes 18, and of which respective pairs are arranged in parallel with one another between the couple of wires 24; and overcurrent detecting-cutting off means 26 each of which is arranged in series with each of the pairs of conductors 20 and which are arranged in parallel with one another between the couple of positive and negative wires 24 along with the conductors 20 and cut off only a current to the pair of conductors 20 through which an overcurrent flows by detecting the overcurrent when the overcurrent flows into the pair of conductors 20.