The 17th Edition requires most if not all circuits in domestic premises to be RCD-protected. There have
been a number of suggestions as to how the consumer unit may best be configured to comply with the
Regulations, the most common being a main switch with RCBOs protecting each individual circuit. However,
another suggestion favours a main switch with two RCDs protecting separate DIN rails. If careful
consideration is given as to what each bar will control in the way of upstairs and downstairs lighting
and power circuits, will this configuration comply?
Yes, as long as the division of final circuits between the RCDs is carefully considered so as to
minimize the consequences of unwanted tripping. Separate RCD protection is not necessarily required for
each circuit of an installation but, in order to minimize the likelihood and consequences of tripping, a
single (‘front end’) RCD should not be used to protect all the circuits.