Kiwi,
One thought just struck me.
As I understand things, (I could be wrong here too) the 1997 Electricity Regulations are no longer in force.
Instead guidance should be sought from AS/NZS 3000:2000, as far as I'm aware these superseded the old Regs.
Section 1.7: Protection for Safety applies to this sort of thing.
In particular, sub-sections 1.7.1- 1.7.4.3.
Hope this helps.
