The assembly of bus bars according to the invention comprises a plurality of sectors of bus bars (S1 to S6) which are arranged, in a connected manner and with electrical contact, around a central axis (C) and upper and lower closing plates (BPD) which are perpendicular to the central axis, the sectors of bus bars each comprising an external portion of bus bar (B11 to B16) and at least one internal portion of bus bar (B21 to B26, B31 to B36) which delimit a plurality of internal volumes, the upper and lower closing plates being in contact against upper and lower faces of the portions of bus bar, respectively, and the portions of bus bar comprising a plurality of electrical contact faces of the type referred to as “press pack”.