... of circuits against short-circuit currents,protection of circuits against overload currents, switch,isolation NB1 circuit-breakers are used in ... considered: the earthing systems(TNS,TNC),short-circuit current at the circuit-breaker installation point, which must always be ... inrush current at the circuit closing(lv/lv transformers,breakdown lamps). Miniature circuit breaker NB1-63 1P 3A UL certificated