The heavy-duty circuit-breaker having an axis (A), and having an arcing contact piece, a current-carrying element and an erosion protection element, with the arcing contact piece having an opening in order to carry an essentially axial flow of a gas which has been heated by an arc, and together with the current-carrying element forms a flat contact (F) in order to carry a short-circuit current (I) which flows through the arcing contact piece and the current-carrying element, and with the erosion protection element essentially shielding the current-carrying element from the flow close to the flat contact (F), is characterized in that the current-carrying element has an axial area in which a radial internal dimension (d2) of the current-carrying element increases in steps or continuously as the distance from the flat contact (F), measured parallel to the axis (A), increases.