The split-load boards here are often installed now with a PME or other solidly grounded system. There's a D.P. main switch feeding a small busbar from which are tapped MCBs for lighting and sometimes other equipment. That busbar also feeds into a large (e.g. 80A, 30mA) RCD which feeds a second busbar from which are tapped MCBs for the other circuits.
The idea is that the RCD/GFI provides added protection for wall outlets etc., but the lights will stay on if it trips. More of a problem with a local-ground system as this would need two RCDs and would start getting expensive.
Do you run separate branch circuits for lights in NZ?
