The governing piece of smoke alarm legislation in the Northern Territory is called the Northern Territory Fire and Emergency Regulations 1996 (as in force 1 October 2019).
Part 2A of this regulation details requirements relating to smoke alarms, notably to do with the type of alarm, installation, maintenance and testing. A summary is provided below;
All owners of residential property must have working smoke alarms installed and tested annually.
Any existing ionization alarms must be replaced with the photoelectric type when they no longer work, the property is sold, or premises are rented out or a lease is renewed.
The responsibility for testing the alarm in a tenanted property lies with the tenant. The tenant must advise the owner or agent if the alarm does not work.
Section 13A (3) of the regulation states that an approved smoke alarm means a photoelectric type that:
(a) complies with Australian Standard 3786 and;
(b) is hard wired or is a sealed 10 year lithium battery unit.
A copy of the Northern Territory Fire and Emergency Regulations 1996 is available for download at the link below if you would like to read it.