Nev:
Good day, and welcome to ECN!
Our resident NZ guy (Trumpy) is on assignment at a sub-station job for about a week. Hopefully, he may check in and respond to you.
I can tell you that here in New Jersey, USA that a homeowner that owns and resides in a single family home can do his own electrical & plumbing work, with a required permit.
That does not apply to anything other than single (1) family homes. NOT rentals, condo's, multi-family, or any commercial properties.
Take care & stay safe.
