P
Paul_C
The problem of isolating a faulty circuit still remains with a single-pole MCB, however. A fault on the neutral can cause the main RCD to trip, depending upon the currents involved from the various loads in use at the time, but one cannot isolate that fault to restore power to the rest of the installation just by turning off the MCB for the faulty circuit, any more than one can isolate it to prevent the main RCD from tripping with a single-pole RCBO.
A D.P. RCBO coupled with a time-delayed main RCD can prevent more than the faulty circuit being isolated automatically when the N-E fault occurs. But beyond that convenience, the reasons for wanting a D.P. rather than an S.P. RCBO are just as valid as arguments for using a D.P. MCB instead of an S.P. type.
A D.P. RCBO coupled with a time-delayed main RCD can prevent more than the faulty circuit being isolated automatically when the N-E fault occurs. But beyond that convenience, the reasons for wanting a D.P. rather than an S.P. RCBO are just as valid as arguments for using a D.P. MCB instead of an S.P. type.