The invention relates to a wire protector, which belongs to selective circuit breaker. The wire protector has a main current circuit, and an auxiliary circuit in which current passes when the main circuit is cut-off after occurrence of a short-circuit. The auxiliary circuit comprises a current limiting resistor including flat coils (5) maintained by two side flanges (1, 3). The resistor includes a variation unit for varying ohmic value of the resistor by association of the coils in parallel.