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 As I understand things, (I could be wrong here too) the 1997 Electricity Regulations are no longer in force. Instead guidance should be sought from AS/NZS 3000:2000, as far as I'm aware these superseded the old Regs.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.