From the main breaker to every group
Inside the panel, power flows from the main breaker through the incomer devices (main RCD, voltage relay) down to the group breakers. Phases are distributed with comb busbars or short wire links; neutrals and protective earth land on dedicated busbars.
Why N must stay in its RCD section
An RCD compares the current leaving through the phase with the current returning through the neutral. If a circuit borrows a neutral from another RCD section, both RCDs see an imbalance and trip even though nothing is broken. That is why every RCD section gets its own N busbar and the neutrals never mix.
Three rules of thumb
- PE is never switched, fused or routed through any device - it goes straight to the PE busbar.
- A panel wire must match the breaker protecting it: 1.5 mm² up to 10 A, 2.5 mm² up to 20 A, 4 mm² up to 25 A, 6 mm² up to 32 A, 10 mm² up to 40 A, 16 mm² above that.
- A comb busbar replaces a fistful of individual jumpers between adjacent breakers: fewer joints, fewer loose terminals, less heat.