Device with at least one movable contact for an apparatus providing protection to at least one line of the circuit-breaker-type provided, in an insulating housing, and for each line, with a fixed contact and with a rotatable movable contact comprising an arm at the free end of which a contact pad is fastened, pivoting between a closed position resting on the fixed contact and an open position away from the fixed contact, - said device comprising a contact carrier(s) connected to a lever controlling the position of the contact(s) via a mechanical lock, also actuated by means of detecting short-circuits or overloads of currents and echoing the movement of the lock to each movable contact, - said contact carrier(s) comprising a number of housings equal to the number of movable contacts, each housing housing the following components: ∘ the other end of the movable contacts, ∘ a fixed support fixed relative to the housing, allowing, on the one hand, the pivoting of said movable contacts in a connection allowing the passage of the current, and on the other hand, the connection to the protected line, ∘ a shaft passing through the other end of the movable contact and the support along the axis of the pivot, and ∘ two torsion/compression spiral springs (23, 23') arranged in a substantially coaxial manner with said shaft, and located on either side of the pivotal connection, - said housings being of cylindrical shape and having an opening allowing the introduction of said components assembled into a hinge subassembly of symmetrical shape with respect to a longitudinal median plane of the movable contact arm, with each housing also having a symmetry with respect to said plane; characterized in that each housing has rectilinear grooves formed in side walls (25, 25') of the housing, substantially perpendicular to the pivot axis and leading into the opening, for housing and guiding the ends of the shaft with a functional clearance, and in that the springs (23, 23') have an end (26, 26') that is substantially rectilinear and designed to abut against an inner face (28, 28') of the housing, constituting the sole bearing zone of the springs (23, 23') on the contact carrier(s), and a bent end (27, 27') adapted to engage a tab (21, 21) protruding in the direction of a lateral wall (25, 25) from the end of the movable contact arranged in the housing, with said tab (21, 21') being located on the side opposite to that of the arm with respect to the pivot axis, said tab (21, 21') and the bent end (27, 27) of the spring (23, 23') being configured and oriented in such a manner so that the latter exerts a double action on the tab (21, 21') firstly in a direction perpendicular to the face (28, 28') of the housing, and secondly in a direction substantially parallel to the axis of the grooves. - said device comprising a contact carrier(s) connected to a lever controlling the position of the contact(s) via a mechanical lock, also actuated by means of detecting short-circuits or overloads of currents and echoing the movement of the lock to each movable contact, - said contact carrier(s) comprising a number of housings equal to the number of movable contacts, each housing housing the following components: ∘ the other end of the movable contacts, ∘ a fixed support fixed relative to the housing, allowing, on the one hand, the pivoting of said movable contacts in a connection allowing the passage of the current, and on the other hand, the connection to the protected line, ∘ a shaft passing through the other end of the movable contact and the support along the axis of the pivot, and ∘ two torsion/compression spiral springs (23, 23') arranged in a substantially coaxial manner with said shaft, and located on either side of the pivotal connection, ∘ the other end of the movable contacts, ∘ a fixed support fixed relative to the housing, allowing, on the one hand, the pivoting of said movable contacts in a connection allowing the passage of the current, and on the other hand, the connection to the protected line, ∘ a shaft passing through the other end of the movable contact and the support along the axis of the pivot, and ∘ two torsion/compression spiral springs (23, 23') arranged in a substantially coaxial manner with said shaft, and located on either side of the pivotal connection, - said housings being of cylindrical shape and having an opening allowing the introduction of said components assembled into a hinge subassembly of symmetrical shape with respect to a longitudinal median plane of the movable contact arm, with each housing also having a symmetry with respect to said plane;