Mechanical breaker apparatus for a high voltage or very high voltage electric circuit, the apparatus being of the type comprising two electrodes (20, 22, 24) each of which is permanently electrically connected to an associated connection terminal, regardless of the open or closed state of the breaker apparatus, the connection terminals being intended to be connected electrically respectively to an upstream portion and to a downstream portion of the electric circuit, the two electrodes of the mechanical apparatus being movable relative to each other in an opening movement between at least one electrically open position and at least one electrically closed position in which they make a nominal electrical connection of the apparatus, said nominal electric connection serving to pass a nominal electric current through the apparatus, the apparatus being of the type including an electric arc splitter device having a multitude of distinct conductive elements (53, 76, 94, 102, 114) that, for at least one active state of the splitter device, are spaced apart and electrically insulated from one another so as to define, in a surrounding insulating fluid, a multitude of successive distinct individual free paths in which electric arcs can be struck on opening and/or closing the electric circuit, the pressure of the fluid being greater than 3 bars absolute, the apparatus being characterized in that the splitter device comprises a first portion and a second portion, at least one of which is movable relative to the other with a relative spacing movement between: - at least one electrical contact position of the two portions defining a continuous electrically-conductive path for the nominal electric current through the apparatus; and - at least one spaced-apart position of the two portions; and in that the splitter device includes at least one series of distinct conductive elements that are arranged along the continuous electrically-conductive path as defined by the two portions of the splitter device in the electrical contact position for passing the nominal electric current through the apparatus, in that, in the electrically closed position of the electrodes (20, 22, 24) of the mechanical apparatus, the nominal electric current, or at least a large portion of it, flows along a main continuous electrically-conductive path, without this majority of the rated current flowing through the splitter device, and in that the continuous electrically-conductive path for the nominal electric current defined by the two portions of the splitter device in the electrical contact position constitutes a secondary continuous electrically-conductive path through the apparatus, along which said distinct conductive elements are arranged. the apparatus being characterized in that the splitter device comprises a first portion and a second portion, at least one of which is movable relative to the other with a relative spacing movement between: - at least one electrical contact position of the two portions defining a continuous electrically-conductive path for the nominal electric current through the apparatus; and - at least one spaced-apart position of the two portions; - at least one electrical contact position of the two portions defining a continuous electrically-conductive path for the nominal electric current through the apparatus; and - at least one spaced-apart position of the two portions; and in that the splitter device includes at least one series of distinct conductive elements that are arranged along the continuous electrically-conductive path as defined by the two portions of the splitter device in the electrical contact position for passing the nominal electric current through the apparatus,