An improved double break contact system for use in moulded case circuit breakers, said double break contact system comprising: shaft means; fixed contact means (1, 2) and moving contact means, said moving contact means being mounted on said shaft means such that said moving contact means rotate with respect to the movement of the shaft means; spring means operatively mounted on the said shaft means; a holder arrangement (5, 7) comprising holder means for securing said spring means; wherein said holder means are rotatably mounted on said shaft means in a manner that rotation of said shaft means in operation rotates said holder means; wherein said spring means are adapted to provide force opposing the electromagnetic force as well as force aiding the electromagnetic force; and wherein said fixed contacts means (1, 2) have a substantially U-shaped profile with a contact portion designed to be contacted by the moving contacts means; characterized in that - said contact portion of the U-shaped profile of the fixed contact means (1, 2) comprises an inward bent portion, - the contact system further comprises shaft cover means for securing the shaft means and the moving contact means, said shaft cover means being in the form of a hollow cylinder having a circumferential wall, said circumferential wall comprising slot means through which the moving contact means protrude outside the shaft cover means, and - said shaft cover means further comprise a plurality of shaft cover flap means projecting outwardly from said circumferential wall, in such a way that, when a moving contact means rotates with respect to the shaft means, the moving contact means touches a respective shaft cover flap means, thereby causing rotation of the shaft cover means. shaft means; fixed contact means (1, 2) and moving contact means, said moving contact means being mounted on said shaft means such that said moving contact means rotate with respect to the movement of the shaft means; spring means operatively mounted on the said shaft means; a holder arrangement (5, 7) comprising holder means for securing said spring means; wherein said holder means are rotatably mounted on said shaft means in a manner that rotation of said shaft means in operation rotates said holder means; wherein said spring means are adapted to provide force opposing the electromagnetic force as well as force aiding the electromagnetic force; and wherein said fixed contacts means (1, 2) have a substantially U-shaped profile with a contact portion designed to be contacted by the moving contacts means; characterized in that - said contact portion of the U-shaped profile of the fixed contact means (1, 2) comprises an inward bent portion, - the contact system further comprises shaft cover means for securing the shaft means and the moving contact means, said shaft cover means being in the form of a hollow cylinder having a circumferential wall, said circumferential wall comprising slot means through which the moving contact means protrude outside the shaft cover means, and - said shaft cover means further comprise a plurality of shaft cover flap means projecting outwardly from said circumferential wall, in such a way that, when a moving contact means rotates with respect to the shaft means, the moving contact means touches a respective shaft cover flap means, thereby causing rotation of the shaft cover means. - said contact portion of the U-shaped profile of the fixed contact means (1, 2) comprises an inward bent portion, - the contact system further comprises shaft cover means for securing the shaft means and the moving contact means, said shaft cover means being in the form of a hollow cylinder having a circumferential wall, said circumferential wall comprising slot means through which the moving contact means protrude outside the shaft cover means, and - said shaft cover means further comprise a plurality of shaft cover flap means projecting outwardly from said circumferential wall, in such a way that, when a moving contact means rotates with respect to the shaft means, the moving contact means touches a respective shaft cover flap means, thereby causing rotation of the shaft cover means.