NCC 2022 Volume One - Building Code of Australia Class 2 to 9 buildings
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20

Specification 20 Smoke detection and alarm systems

Specification 20 Smoke detection and alarm systems

This Specification describes the installation and operation of automatic smoke detection and alarm systems.

To state that Specification 20 relates to the installation and operation of automatic alarm systems.

Automatic smoke detection and alarm systems

Specification 20 covers the technical requirements for smoke detection and alarm systems, including such detection as is necessary to activate smoke control systems.

A required automatic smoke detection and alarm system must be provided in accordance with the following:

  1. Class 2 buildings and Class 4 parts of a building—
    1. a smoke alarm system complying with S20C3; or
    2. a smoke detection system complying with S20C4; or
    3. a combination of a smoke alarm system and a smoke detection system complying with S20C5.
  2. Class 3 buildings—
    1. with a Class 3 part located more than 2 storeys above ground level — a smoke detection system complying with S20C4; or
    2. which accommodate more than 20 residents and are the residential part of a school, accommodation for the aged, children or people with a disability — a smoke detection system complying with S20C4; or
    3. all other Class 3 buildings—
      1. a smoke alarm system complying with S20C3; or
      2. a smoke detection system complying with S20C4; or
      3. a combination of a smoke alarm system and a smoke detection system complying with S20C5.
  3. Class 5, 6, 7, 8, 9b and 9c buildings — a smoke detection system complying with S20C4
  4. Class 9a health-care buildings—
    1. where more than 6 bed patients are accommodated — a smoke detection system complying with S20C4; or
    2. where 6 or less bed patients are accommodated—
      1. a smoke alarm system complying with S20C3; or
      2. a smoke detection system complying with S20C4.

To specify compliance requirements for required automatic smoke detection and alarm systems.

Types of smoke detection and alarm systems

S20C2 covers smoke detection and alarm systems directly referenced in Part E2. The application of smoke detection to smoke control systems is addressed in S20C6.

S20C2 indicates the types of system, in terms of smoke alarm and/or smoke detection, applicable to various Classes of buildings. A smoke detection system is considered necessary in certain Class 3 and Class 9a buildings to facilitate system monitoring as required by S20C8.

Smoke alarm systems

Smoke alarm systems are required in:

  • Class 2 buildings;
  • smaller Class3 buildings (see S20C2(b) regarding larger Class 3 buildings);
  • Class 4 parts; and
  • smaller Class9a buildings (see S20C2(d)(i) regarding larger Class 9a buildings).

Smoke detection systems

Smoke detection systems are required (and in some cases are the sole requirement to satisfy smoke hazard management provisions) in:

  • Class 2 buildings;
  • smaller Class 3 buildings;
  • larger Class 3 buildings;
  • Class 4 parts;
  • Class 5–8 and Class 9b buildings (note that a smoke detection system complying with S20C4 and not a smoke alarm system complying with S20C3 is required in these buildings);
  • smaller Class9a building (see S20C2(d)(i) regarding larger Class 9a buildings);
  • larger Class 9a buildings (note that a smoke detection system complying with S20C4 and not a smoke alarm system complying with S20C3 is required in these buildings); and
  • Class 9c buildings.

Combined systems

Combined smoke alarm and smoke detection systems are permitted (as specified) in:

  • Class 2 buildings;
  • smaller Class 3 buildings (see S20C2(b) regarding larger Class 3 buildings); and
  • Class 4 parts.

A smoke alarm system and a smoke detection system are only required to be installed when required by Part E2.

(1) In all Class 2 to 9 buildings provided with a smoke alarm system, the following applies:

  1. A smoke alarm system must—
    1. consist of smoke alarms complying with AS 3786; and
    2. be powered from the consumer mains source.
  2. In kitchens and other areas where the use of the area is likely to result in smoke alarms causing spurious signals, subject to (c)—
    1. any other alarm deemed suitable in accordance with AS 1670.1 may be installed provided that smoke alarms are installed elsewhere in the sole-occupancy unit in accordance with (2)(a) and (2)(b); or
    2. an alarm acknowledgement facility may be installed.
  3. Where a kitchen or other area referred to in (b) is in a building protected with a sprinkler system complying with Specification 17 (other than a FPAA101D system), alarms need not be installed in the kitchen or other area likely to result in spurious signals.

(2) In a Class 2 or 3 building or Class 4 part of a building provided with a smoke alarm system, the following applies:

  1. Alarms must be installed within each sole-occupancy unit, and located on or near the ceiling in any storey—
    1. containing bedrooms—
      1. between each part of the sole-occupancy unit containing bedrooms and the remainder of the sole-occupancy unit; and
      2. where bedrooms are served by a hallway, in that hallway; and
    2. not containing any bedrooms, in egress paths.
  2. Where there is more than one alarm installed within a sole-occupancy unit, alarms must be interconnected within that sole-occupancy unit.
  3. Subject to (d), alarms must be—
    1. installed in public corridors and other internal public spaces, located in accordance with the requirements for smoke detectors in AS 1670.1; and
    2. connected to activate a building occupant warning system in accordance with S20C7.
  4. In a Class 2 or 3 building or Class 4 part of a building protected with a sprinkler system complying with Specification 17 (other than a FPAA101D system), alarms are not required in public corridors and other internal public spaces.

(3) In a Class 9a building provided with a smoke alarm system, smoke alarms must be—

  1. installed in every room, public corridor and other internal public space; and
  2. located in accordance with the requirements for smoke detectors in AS 1670.1; and
  3. interconnected to provide a common alarm; and
  4. have manual call points installed in evacuation routes so that no point on a floor is more than 30 m from a manual call point.

To specify requirements for required automatic smoke alarm systems.

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.

(1) In all Class 2 to 9 buildings provided with a smoke detection system, the following applies:

  1. A smoke detection system must—
    1. subject to (2), (3) and (4), comply with AS 1670.1; and
    2. activate a building occupant warning system in accordance with S20C7.
  2. In kitchens and other areas where the use of the area is likely to result in smoke detectors causing spurious signals, subject to (c)—
    1. any other detector deemed suitable in accordance with AS 1670.1 may be installed provided that smoke detectors are installed elsewhere in the sole-occupancy unit in accordance with the requirements for alarms in S20C3(2)(a) and (2)(b); or
    2. an alarm acknowledgement facility may be installed.
  3. Where a kitchen or other area referred to in (b) is in a building protected with a sprinkler system complying with Specification 17 (other than a FPAA101D or FPAA101H system), detectors need not be installed in the kitchen or other areas likely to result in spurious signals.

(2) In a Class 2 or 3 building or Class 4 part of a building provided with a smoke detection system, the following applies:

  1. Smoke detectors must be installed—
    1. within each sole-occupancy unit, in accordance with the requirements for alarms in S20C3(2)(a) and (2)(b); and
    2. subject to (b), in public corridors and other internal public spaces.
  2. In a Class 2 or 3 building or Class 4 part of a building protected with a sprinkler system complying with Specification 17 (other than a FPAA101D or FPAA101H system), smoke detectors are not required in public corridors and other internal public spaces.

(3) In a Class 9a health-care building provided with a smoke detection system, the following applies:

  1. Except as provided in (b)—
    1. photoelectric type smoke detectors must be installed in patient care areas and in paths of travel to exits from patient care areas; and
    2. in areas other than patient care areas and paths of travel to exits from patient care areas, where the use of the area is likely to result in smoke detectors causing spurious signals, any other detector deemed suitable in accordance with AS 1670.1 may be installed in lieu of smoke detectors.
  2. The requirements of (a) do not apply where an area is protected with a sprinkler system complying with Specification 17, smoke detectors need not be installed where the use of the area is likely to result in spurious signals.
  3. Manual call points must be installed in evacuation routes so that no point on a floor is more than 30 m from a manual call point.

(4) In a Class 9c building provided with a smoke detection system, the following applies:

  1. remote automatic indication of each zone must be given in each smoke compartment by means of—
    1. mimic panels with an illuminated display; or
    2. annunciator panels with alpha numeric display; and
  2. if the building accommodates more than 20 residents, manual call points must be installed in paths of travel so that no point on a floor is more than 30 m from a manual call point.

VIC S20C4 Smoke detection system2019: Spec E2.2a: 4

Delete subclause S20C4(4) and insert S20C4(4) as follows:

(4) In a Class 9c building provided with a smoke detection system—

  1. if the building accommodates more than 20 residents, manual call points must be installed in paths of travel so that no point on a floor is more than 30 m from a manual call point; and
  2. indication of the zone where the smoke detection system has actuated must be achieved by one of the following:
    1. Option 1—
      1. remote automatic indication of each zone must be given in each smoke compartment; and
      2. indication of (A) must be indicated on remote annunciator panels with alpha-numeric displays with a minimum of 20 characters of 9 mm minimum height.
    2. Option 2—
      1. indication of the zone where the smoke detection system has actuated must be communicated via a suitable interface with the fire indicator panel to a portable remote communication device; and
      2. at least one such portable remote communication device per smoke compartment must be provided to staff nominated by the owner or operator and properly instructed as to the duties and responsibilities involved; and
      3. the portable remote communication device may be a pager with alpha-numeric display or portable telephone handset with capability of receiving alpha-numeric display.

To specify requirements for required automatic smoke detection systems.

Smoke detection systems—S20C4(1)
S20C4(1)(b)(i) specifies the circumstances in which AS 1670.1 applies.

S20C4(1)(b)(ii) specifies that the smoke detection system must activate a suitable building occupant warning system. Both apply subject to S20C4(1)(c).

Use of other suitable detectors—S20C4(1)(b)
A smoke detector can give false alarms if the atmosphere contains particles, such as steam or other vapours which obscure vision. For example, in a kitchen or bathroom these conditions may be present. S20C4(1)(b) therefore allows the use of a more suitable detector in these locations. It is important that the detector used is suitable for the location and type of fire likely to occur. The suitability of detectors 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.

Residential buildings—S20C4(2)
S20C4(2) details the installation requirements for automatic smoke detection systems in residential buildings (excluding Class 9 buildings).

In buildings which do not contain a sprinkler system complying with Specification 17 (other than a FPAA101D or FPAA101H system), S20C4(2)(a)(ii) requires smoke detectors 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, commercial storerooms, cleaner’s rooms, service cupboards or the like.

S20C4(2)(a)(i) references S20C3(2)(a) and (b) which require 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).

Health-care buildings—S20C4(3)
S20C4(3) applies to all Class 9a buildings which have a smoke detection system. S20C3(a)(i) applies to both within the patient-care area and the path of travel after a person leaves the patient-care area.

Where an area within a health-care building is likely to cause spurious signals, and the area is protected with a sprinkler system complying with Specification 17, S20C4(3)(b) provides a concession to the smoke detector requirements.

Manual call points are required in evacuation routes in view of the nature of the occupancy.

Class 9c residential care buildings—S20C4(4)
In a Class 9c residential care building, an automatic smoke detection system must be installed in accordance with AS 1670.1. Subject to S20C4(1), Clause 3.27 of AS 1670.1 lists areas where detectors are required. Manual call points are also necessary in larger buildings in view of the nature of the occupancy.

(1) A Class 2 or 3 building or Class 4 part of a building provided with a combination of a smoke alarm system and smoke detection system in accordance with S20C2 must—

  1. be provided with a smoke alarm system complying with S20C3 within sole-occupancy units; and
  2. subject to (2), be provided with a smoke detection system complying with S20C4 in areas not within sole-occupancy units.

(2) In a Class 2 or 3 building or Class 4 part of a building protected with a sprinkler system complying with Specification 17 (other than a FPAA101D or FPAA101H system), smoke detectors are not required in public corridors and other internal public spaces.

To specify requirements for combined smoke alarm and smoke detection systems.

Combined smoke alarm and smoke detection systems—S20C5(1)

S20C2 specifies the circumstances in which S20C5 applies.

S20C5(1)(a) requires smoke alarms which comply with AS 3786 to be located within each sole-occupancy unit in accordance with S20C3.

In buildings which do not contain a sprinkler system complying with Specification 17 (other than a FPAA101D or FPAA101H system), S20C5(1)(b) requires smoke detectors which comply with AS 1670.1 to be installed in public corridors and other internal public spaces in accordance with S20C4.

(1) Smoke detectors required to activate air pressurisation systems for fire-isolated exits and zone pressurisation systems must—

  1. be installed in accordance with AS 1670.1; and
  2. have additional smoke detectors installed adjacent to each bank of lift landing doors set back horizontally from the door openings by a distance of not more than 3 m.

(2) Smoke detectors required to activate—

  1. automatic shutdown of air-handling systems in accordance with E2D16, E2D17 or E2D19; or
  2. a smoke exhaust system in accordance with Specification 21,

must comply with the requirements of (3).

(3) Smoke detectors referred to in (2) must—

  1. be spaced—
    1. not more than 20 m apart and not more than 10 m from any wall, bulkhead or smoke curtain; and
    2. in enclosed malls and walkways in a Class 6 building not more than 15 m apart and not more than 7.5 m from any wall, bulkhead or curtain; and
  2. have a sensitivity—
    1. in accordance with AS 1670.1 in areas other than a multi-storey walkway and mall in a Class 6 building; and
    2. not exceeding 0.5% smoke obscuration per metre with compensation for external airborne contamination as necessary, in a multi-storey walkway and mall in a Class 6 building.

(4) Smoke detectors provided to activate a smoke control system must—

  1. either—
    1. form part of a building fire or smoke detection system complying with AS 1670.1; or
    2. be a separate dedicated system incorporating control and indicating equipment complying with AS 1670.1; and
  2. activate a building occupant warning system complying with S20C7, except that smoke detectors provided solely to initiate automatic shutdown of air-handling systems in accordance with (2)(a) need not activate a building occupant warning system.

To specify the smoke detection requirements applicable to smoke control systems.

AS 1668.1 systems—S20C6(1)

S20C6(1) covers smoke detection associated with AS 1668.1 stair pressurisation systems referenced in Part E2. It requires the installation of additional detectors adjacent to each bank of lift landing doors. Lift shafts form one of the principal paths for smoke spreading between floors in a multi-compartmented building.

Location and sensitivity—S20C6(2) and (3)

S20C6(2) and (3) cover the location and sensitivity of smoke detectors associated with smoke control systems referenced in:

  • E2D16, E2D17 or E2D19, regarding automatic shutdown of air-handling systems.
  • Specification 21, regarding the smoke exhaust system.

Activation—S20C6(4)

Under S20C6(4), smoke detectors which activate a smoke control system must:

  • form part of the building’s AS 1670.1 smoke detection system or be a separate dedicated system; and
  • activate a building occupant warning system complying with S20C7, unless they initiate shutdown of an automatic air- handling system only, in which case they need not activate a building occupant warning system.

Subject to E4D9, a building occupant warning system provided as part of a smoke hazard management system must comply with clause 3.22 of AS 1670.1 to sound through all occupied areas except—

  1. in a Class 2 and 3 building or Class 4 part of a building provided with a smoke alarm system in accordance with S20C3(2)(c)—
    1. the sound pressure level need not be measured within a sole-occupancy unit if a level of not less than 85 dB(A) is provided at the door providing access to the sole-occupancy unit; and
    2. the inbuilt sounders of the smoke alarms may be used to wholly or partially meet the requirements; and
  2. in a Class 2 and 3 building or Class 4 part of a building provided with a smoke detection system in accordance with S20C4(2), the sound pressure level from a building occupant warning system need not be measured within a sole-occupancy unit if a level of not less than 100 dB(A) is provided at the door providing access to the sole-occupancy unit; and
  3. in a Class 3 building used as a residential care building, the system—
    1. must be arranged to provide a warning for occupants; and
    2. in areas used by residents, may have its alarm adjusted in volume and content to minimise trauma consistent with the type and condition of residents; and
  4. in a Class 9a health-care building, in a patient care area, the system—
    1. must be arranged to provide a warning for occupants; and
    2. in a ward area, may have its alarm adjusted in volume and content to minimise trauma consistent with the type and condition of the patients; and
  5. in a Class 9c building, the system—
    1. must be arranged to provide a warning for occupants; and
    2. must notify staff caring for the residents of the building; and
    3. in areas used by residents, may have its alarm adjusted in volume and content to minimise trauma consistent with the type and condition of residents.

To specify the application of building occupant warning systems.

Residential buildings—S20C7(a) and (b)

Because of the protection provided by the fire compartmentation of sole-occupancy units in residential buildings, it is not mandatory for a building occupant warning system to have sounders or speakers installed within each sole-occupancy unit. Accordingly, S20C7(a) and (b) provide for the sound pressure levels to be measured at the entry to each sole- occupancy unit.

Residential care and health-care buildings—S20C7(c) and (d)

S20C7(c) and (d) provide for the warning signals to be modified in certain areas within residential care and health-care buildings to minimise trauma to occupants who may be confused or immobile. However, in such instances, adequate warning must always be available to staff, carers, employees and the like.

Class 9c buildings—S20C7(e)

S20C7(e) requires warning signals to be modified in certain areas within Class 9c buildings to minimise trauma to residents who may be confused or immobile. However, in such instances, adequate warning must always be available to staff, carers, employees and the like. Residential care facilities may contain more than one building. Nevertheless, staff are required to be notified irrespective of their location.

Occupiable outdoor areas

S20C7 requires a building occupant warning system provided as part of a smoke hazard management system to sound through all occupied areas. An occupiable outdoor area is part of a building, therefore a required occupant warning system must sound in an occupiable outdoor area.

Additional provisions in E4D9

The separate provisions under E4D9 are for emergency warning and intercom systems for emergency purposes in certain buildings.

NCC Blurbs

The following installations must be connected to a fire alarm monitoring system connected to a fire station or fire station dispatch centre in accordance with AS 1670.3:

  1. A smoke detection system in a Class 3 building provided in accordance with S20C2(b)(i) or S20C2(b)(ii).
  2. A smoke detection system in a Class 9a health-care building, if the building accommodates more than 20 patients.
  3. A smoke detection system in a Class 9c building.
  4. Smoke detection in accordance with S20C6 provided to activate—
    1. a smoke exhaust system in accordance with Specification 21; or
    2. smoke-and-heat vents in accordance with Specification 22.
NCC Title
System monitoring
NCC State
NSW
NCC Variation Type
Replacement
NCC SPTC Current
System monitoring
NCC Blurbs

The following installations must be connected to a fire alarm monitoring system connected to a fire station or a fire station dispatch centre in accordance with AS 1670.3:

  1. A smoke detection system in a Class 3 building provided in accordance with S20C2(b)(i) or (ii).
  2. A smoke detection system in a Class 9a health-care building, if the building accommodates more than 20 patients, unless the building is sprinklered and the sprinkler system is permanently connected to a fire station, or other approved monitoring service with a direct data link to a fire station, in accordance with Building Practice Note FS-01.
  3. Smoke detection in accordance with S20C6 provided to activate—
    1. a smoke exhaust system in accordance with Specification 21; or
    2. smoke-and-heat vents in accordance with Specification 22.
  4. An automatic fire detection and alarm system required by E2D10 for large isolated buildings subject to C3D4.
NCC Title
System monitoring
NCC State
VIC
NCC Variation Type
Replacement
NCC SPTC Current
System monitoring

The following installations must be connected to a fire alarm monitoring system connected to a fire station or fire station dispatch centre in accordance with AS 1670.3:

  1. A smoke detection system in a Class 3 building provided in accordance with S20C2(b)(i) or S20C2(b)(ii).
  2. A smoke detection system in a Class 9a health-care building, if the building accommodates more than 20 patients.
  3. A smoke detection system in a Class 9c building.
  4. Smoke detection in accordance with S20C6 provided to activate—
    1. a smoke exhaust system in accordance with Specification 21; or
    2. smoke-and-heat vents in accordance with Specification 22.
  5. An automatic fire detection and alarm system required by E2D10 for large isolated buildings subject to C3D4.

To specify the system monitoring requirements in high risk occupancies.

High risk occupancies

S20C8 specifies the system monitoring requirements in high risk occupancies, to enable a timely and appropriate response by the local fire brigade to emergencies in such buildings as:

  • certain residential, health-care and aged care buildings;
  • shops and assembly buildings provided with mechanical or natural smoke extraction systems; and
  • large un compartmented factories and warehouses.

The standard referenced for the alarm monitoring system is AS 1670.3.