To separate the loads, some protected by earth leakage and some only protected by over current to reduce nuisance tripping (split neutral busbars).
This is a practical demonstration that took place in a laboratory.
For Samite rail please see: https://youtu.be/VHyFl-y7XCA
Further details in the SANS 10142-1:2020 wiring standard - The Wiring of Premises Part1: low voltage installations.