Smoke alarm systems—S20C3(1)
Smoke alarm systems must include smoke alarms which comply with AS 3786 (see S20C3(1)(a)(i)).

Power to smoke alarm systems must come from the electrical power supply to that part of the building served by the smoke alarm system.

Use of other suitable alarms—S20C3(1)(b)
A smoke alarm can give false alarms if the atmosphere contains particles, such as steam or other vapours, which obscure vision. For example, in a kitchen or a bathroom these conditions may be present. S20C3(1)(b) therefore allows the use of a more suitable alarm in these locations. It is important that the alarm used is suitable for the location and type of fire likely to occur. The suitability of alarms can be determined by reference to AS 1670.1. The alternative of an alarm acknowledgement facility complying with AS 1670.1 provides occupants with an opportunity to mitigate the effects of spurious or unwarranted alarms.

Smoke alarms and residential buildings—S20C3(2)
S20C3(2) details the installation requirements for automatic smoke alarms in residential buildings (excluding Class 9 buildings).

S20C3(2)(b) requires alarms located within each sole-occupancy unit to be interconnected to provide a common alarm so that if one alarm sounds then other alarms in the sole-occupancy unit automatically activate, which will increase the likelihood of sleeping occupants being aware of the smoke. The word ‘alarm’ includes any type of alarm allowed under S20C3(1)(b)(i).

Smoke alarms located outside the sole-occupancy units, in public corridors and other common areas within the building, must be interconnected to provide a common building alarm in order to alert all building occupants to the potential hazard in the common evacuation routes.

In buildings which do not contain a sprinkler system complying with Specification 17, S20C3(2)(c) requires smoke alarms to be installed in public corridors and other internal public spaces. Such spaces would include public foyers, reception areas and enclosed carparks. However, these spaces would not include fire-isolated exits, as they are subject to separate smoke hazard management provisions.

Smoke alarms and health-care buildings—S20C3(3)
The application of S20C3(3) is limited by the provisions of S20C2(d) to small health-care buildings, where not more than six patients are accommodated in beds.

S20C3(3) requires smoke alarms to be installed in public corridors and other internal public spaces. Such spaces would include public foyers, reception areas and enclosed carparks. However, these spaces would not include fire-isolated exits, as they are subject to separate smoke hazard management provisions.

Interconnection of smoke alarms is required due to the level of compartmentation and the need to alert staff to help occupants who may be confused, non-ambulatory or otherwise dependent on assistance. Manual call points are also necessary in view of the nature of the occupancy.