How an ELCB helps in maitaining electrical safety for human

elcb (earth leakage circuit breaker) is consisting of ct (current transformers) built inside on each line. For example, 2 pole elcb will have 2 cts i.e. One on live i.e. Phase wire and second on neutral wire. Normal function of this is based on principal: I1 + i2 = 0. This happens in normal functioning of elcb. But if one of the lead in circuit gets leaked or follow other than intended path then, i1 + i2 is not equal to zero. This not equal to zero means some value of current tends to actuates tripping mechanism of the elcb thus avoiding electric shock to human being or not causing any short / leakage in circuit.