The short answer
- RCD reacts to leakage current only and must be paired with MCBs.
- RCBO combines an RCD and an MCB in one module: leakage, overload and short-circuit protection for a single circuit.
When an RCD group makes sense
One RCD protecting a group of MCBs is cheaper and saves panel space. The downside: a leak on any circuit in the group switches off the whole group.
When RCBOs are better
Critical circuits (fridge, freezer, home office) deserve their own RCBO, so a faulty kettle cannot switch them off. RCBOs cost more per circuit but give the best selectivity.
What PlanMyPanel does
The generator groups ordinary circuits under shared RCDs and gives dedicated RCBOs to circuits where a nuisance trip would be costly.