24
Installation with a central RCCB
Figure 8 shows a frequent type of installation with a central RCCB, downstream of
which several miniature circuit breakers are connected for each phase conductor.
The RCCB provides electric-shock protection and re protection as well as the
additional protection with I
Δn
≤ 30 mA against direct contact as required for certain
circuits (e.g. in bathrooms). The miniature circuit breaker prevents damage due to
overloads or short circuits. If the RCCB is tripped in one of the downstream circuits
due to a ground fault, all other circuits, even the fault-free circuits, are disconnec-
ted from the voltage supply. Operation of these parts of the installation can only
be resumed after the fault has been eliminated. The following factors must be
taken into account with this type of installation:
• For correct dimensioning of the installation in respect of the residual current
operated circuit breaker (RCCB), it must be ensured that the RCCB is not over-
loaded due to excessively high load currents (see section 5.5).
• In the de-energized state, the single-pole miniature circuit breakers only dis-
connect the phase conductor from the network. The neutral conductor remains
connected to the load side.
• The tripping of a residual current protective device is not allowed to lead to
the failure of all circuits in a system.
Residual current protective devices
Figure 8: Installation with a central RCCB and miniature circuit breakers for feeders
RCBO
AFD
RCBO
AFD
RCBO
AFD
RCBO
AFD
MCB
AFD
MCB
AFD
MCB
AFD
Counter
RCD
Socket outlet
circuit 1
Dishwasher
Washing
machine
Lighting 1
Lighting 2
Lighting 3
Socket outlet
circuit 2
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