Building Technical Update: Are your smoke alarms installed correctly?

Friday July 29 2016

Feedback to the Victorian Building Authority's (VBA) Proactive Inspections Team from building surveyors and building inspectors indicates some electricians and builders remain uncertain about requirements for the location and installation of smoke alarms in dwellings in Victoria (Class 1 buildings).

Inspections have revealed that smoke alarms are being installed incorrectly by:

  • Being positioned too close to walls or ridges in cathedral ceilings
  • Not being installed on each level of the dwelling
  • Not being interconnected where there is more than one smoke alarm serving the dwelling
  • In some instances, not being connected to the consumer mains power (by installing battery operated smoke alarms)

What should be done?

The VBA reminds builders and electricians that smoke alarms must be:

  •  Located:
    • Between 300mm and 500mm from the cornice, if installed on a wall
    • More than 300mm from the cornice, if installed on flat ceilings
    • Between 500mm and 1500mm from ridges of cathedral ceilings
    • Under exposed floor joists
    • On each storey of the dwelling, even where the storey does not contain a bedroom
    • Interconnected where there are multiple smoke alarms serving the dwelling
    • Connected to the consumer mains power.

What can practitioners do?

Draftspersons and architects should ensure the location of all smoke alarms is specified on the floor plan. They should also record details of all relevant notes and specifications, including the requirement to interconnect them and ensure they are hard-wired to consumer mains.

Builders and electricians should ensure at the electrical rough-in stage, prior to plastering, that the interconnecting electrical cables are installed.

At the electrical fit-off stage, electricians should ensure smoke alarms are clear from walls and ceilings in accordance with Part 3.7.2 of Volume 2 of the Building Code of Australia (see the BCA extract below). Remember: the distance measured is not from the wall to the centre of the smoke alarm, but from the wall to the first edge of the smoke alarm.

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