Hi there the wirings colour codes for nz are as follows

OLD WIRING CODE

Green = Earth
Black = Neutral
Red = Phase Or Live

NEW WIRING CODE

Green/Yellow = Earth
Blue = Neutral
Brown = Phase or Live

============DANGER 230VOLT ===============

Electricity can kill.
You should use an Electrical contractor for this repair job,
Caution always turn off power first before touching any wiring,

The Live wires always carry power,from one point to another,
the black neutral is your return path from the live phase wire
the green wire is always the ground ,

In this example

the sensor will have four wires as follows

Green = Earth Wire
Black = Neutral
Brown = Phase (incoming supply) 24 hrs
Red = Phase Load (outgoing supply) from sensor to lights triggered

Notice there are to phases in the circuit.Brown and Red
Always treat them as LIVE or Active Power.

Brown will normally be the Live incoming power and
Red will be the load side of the sensor,

Check the brochure supplied by manufactuers or their website to confirm the wiring order is correct before commencing any installs or repairs,

Always Safety first.
Safe a live today and you'll remembered forever.

I have a sl-6107 motion sensor. it has 4 wires green-ground, black-hot, red - i would assume switched hot, and brown-?

This is a 3 pole switch
Black = Hot or Load
Green = Ground
Brown and Red are travelers.
Link to proper literature regarding this switch:
http://solutions.cooperwiringdevices.com/webDB/documents/cwd%20residential/instrSheets/469MT-PTA%20(REV.%20A).pdf