... or two,three,four poles up to 45V circuit for overload and short circuit protection.as well as for unfrequently switching on ... &off electric equipment and lighting circuit in normal case.the product comply with IEC60898&GB10963-1999 ... than 6000 operationsmechanical life:(O-C) on less than 20000 circuit breaker,new type,C451 (MCB)