Alternatively changeable electric circuit, comprising at least a source of a direct or alternative voltage, at least one electric load, which is via a primary branch and a secondary branch of a basic electric conductor electrically connected with said electric voltage source, wherein an alternative conductor is connected in parallel to said basic electric conductor, so that in each predetermined circumstances i.e. by fulfilling each predetermined conditions said primary branch is physically interrupted, upon which the electric current, which initially flowed through said primary branch, is then redirected through said alternative electric conductor, wherein said alternative electric conductor, which is in parallel connected with each corresponding branch of said basic conductor, consists of two electric conductive sections (231, 232), which are aligned with each other and spaced apart from each other at a predetermined distance, so that an electrically insulating gap is formed there-between, and that said branch of the basic conductor includes an electrically conductive section, which is in each predetermined circumstances i.e. by fulfilling each predetermined conditions physically removable from the rest of said branch and displaceable into said gap between said sections (231, 232) of the alternative conductor, which herewith becomes bridged and electrically conductive, and wherein said electrically conductive section represents a part of material of said branch of the basic electric conductor, which is furnished with at least one mechanically weakened area (211, 212) and is in said weakened area (211, 212) by means of appropriate mechanical loading separable apart from the residual material of said branch, and wherein said weakened area (211, 212) is an area, in which the transversal cross-section is essentially smaller than in the residual areas of the branch of the basic electric conductor, and wherein said circuit, in addition to said conductors (21, 22, 23), also comprises a pyrotechnic actuator, which is suitable for being triggered in each predetermined circumstances and by fulfilling each predetermined conditions, and is arranged adjacent to said section of said weakened branch of the basic conductor, so that said section is by means of said pyrotechnic actuator mechanically separable apart from the rest of said branch and displaceable into the gap between said sections (231, 232) of the alternative conductor, characterized in that said removable section of the branch of the basic electric conductor, which is furnished with said weakened portion (211, 212), is on that its side, which is faced towards said pyrotechnic actuator, furnished with a concave cavity, and is moreover on its opposite side, which is faced towards said gap between said sections (231, 232) of the alternative conductor, furnished with a convex external surface (210"), which is suitable for being impressed and jammed between said sections (231, 232) of the alternative electric conductor within the gap. and wherein said electrically conductive section represents a part of material of said branch of the basic electric conductor, which is furnished with at least one mechanically weakened area (211, 212) and is in said weakened area (211, 212) by means of appropriate mechanical loading separable apart from the residual material of said branch, and wherein said weakened area (211, 212) is an area, in which the transversal cross-section is essentially smaller than in the residual areas of the branch of the basic electric conductor, and wherein said circuit, in addition to said conductors (21, 22, 23), also comprises a pyrotechnic actuator, which is suitable for being triggered in each predetermined circumstances and by fulfilling each predetermined conditions, and is arranged adjacent to said section of said weakened branch of the basic conductor, so that said section is by means of said pyrotechnic actuator mechanically separable apart from the rest of said branch and displaceable into the gap between said sections (231, 232) of the alternative conductor, characterized in that said removable section of the branch of the basic electric conductor, which is furnished with said weakened portion (211, 212), is on that its side, which is faced towards said pyrotechnic actuator, furnished with a concave cavity, and is moreover on its opposite side, which is faced towards said gap between said sections (231, 232) of the alternative conductor, furnished with a convex external surface (210"), which is suitable for being impressed and jammed between said sections (231, 232) of the alternative electric conductor within the gap.