Busbar comprising: - a casing comprising a plurality of sidewalls that delimit a cavity , - a tap-off opening formed in at least one of said sidewalls , - a plurality of busbar conductors arranged parallel inside said cavity , wherein each busbar conductor extends along a longitudinal direction (X-X), is spaced from the adjacent busbar conductor along a first direction (Y-Y) perpendicular to the longitudinal direction (X-X) and has a central portion and two edge portions spaced from each other by the central portion , said edge portions of the busbar conductors extend longitudinally and are spaced from each other along a second direction (Z-Z) perpendicular to the longitudinal direction (X-X) and to the first direction (Y-Y), - clamping members externally coupled to said casing for holding said plurality of busbar conductors inside said casing , - a plurality of tap-off elements , each tap-off element being stably fixed to a respective busbar conductor and passing through said tap-off opening in order to bring electric current from said plurality of busbar conductors to a power supply system, - said plurality of busbar conductors extend along a straight direction inside said casing so that the distance between the busbar conductors along the first direction (Y-Y) is constant inside said casing , characterized in that: - in each busbar conductor , the thickness of the central portion and of at least one of said two edge portions , as measured in the first direction (Y-Y), have values s1 and s2 respectively, s2 being less than s1, - each tap-off element is stably fixed to a respective busbar conductor at a contact surface of said at least one edge portion having a thickness s2, the contact surface of the busbar conductor and the tap-off element being welded together. - a casing comprising a plurality of sidewalls that delimit a cavity , - a tap-off opening formed in at least one of said sidewalls , - a plurality of busbar conductors arranged parallel inside said cavity , wherein each busbar conductor extends along a longitudinal direction (X-X), is spaced from the adjacent busbar conductor along a first direction (Y-Y) perpendicular to the longitudinal direction (X-X) and has a central portion and two edge portions spaced from each other by the central portion , said edge portions of the busbar conductors extend longitudinally and are spaced from each other along a second direction (Z-Z) perpendicular to the longitudinal direction (X-X) and to the first direction (Y-Y), - clamping members externally coupled to said casing for holding said plurality of busbar conductors inside said casing , - a plurality of tap-off elements , each tap-off element being stably fixed to a respective busbar conductor and passing through said tap-off opening in order to bring electric current from said plurality of busbar conductors to a power supply system, - said plurality of busbar conductors extend along a straight direction inside said casing so that the distance between the busbar conductors along the first direction (Y-Y) is constant inside said casing , - in each busbar conductor , the thickness of the central portion and of at least one of said two edge portions , as measured in the first direction (Y-Y), have values s1 and s2 respectively, s2 being less than s1, - each tap-off element is stably fixed to a respective busbar conductor at a contact surface of said at least one edge portion having a thickness s2, the contact surface of the busbar conductor and the tap-off element being welded together. <EOS>