Chint NB1L Residual Current Operated Circuit Breaker with over-current protection (Magnetic)General 1. 1 Function Personnel and fire protection: Cable and line protection against overload and short circuits. 1. 2 Selection Rated residual operating current In 30 mA: additional protection in the case of direct contact. In 300 mA: preventative fire protection in the case of ground fault currents. Tripping class AC class Tripping is ensured for sinusoidal, alternating currents, whether they be quickly applied or slowly increase. A class Tripping