People who are sleeping do not smell smoke and are unlikely to wake up in the event of a fire, so the most effective way to ensure they do wake up is by installing smoke alarms.

On this page:

• types of smoke alarm
• domestic smoke alarm requirements
• installation
• maintenance of smoke alarms.

Types of smoke alarm

Smoke alarms detect the smoke particles from a fire. There are two common types:

• A photo-electric smoke alarm, which uses a beam of light and a light sensor. When smoke particles affect the amount of light reaching the sensor, an alarm will sound.
• An ionisation smoke alarm, which monitors the ions (electrically charged particles). When the electrical balance of the air is altered by the smoke particles, the alarm will sound.

The NZ Fire Service recommends that photo-electric alarms be installed in households or, if ionisation alarms are currently installed, they should be supplemented with photo-electric alarms as these provide more effective, all-round detection.

Smoke alarms are available with extra loud alarms, flashing lights or vibrating devices for people with hearing loss.

To be effective, an installed smoke alarm must be operating properly, audible through closed doors and able to detect smoke from all types of fires.

Domestic smoke alarms are typically battery-powered and provide good warning of the presence of smoke and fire as long as batteries are replaced regularly. Mains-connected systems (with battery back-up in the event of a power failure) are also available.

Domestic smoke alarm requirements

The New Zealand Building Code requires that all new houses and all existing houses undergoing alteration have smoke alarms installed. Domestic smoke alarms must be Type 1, which has:

• a hush button so the alarm can be cleared without shutting off power (i.e. by removing the battery)
• a test button.

Installation

Smoke alarms should be installed

• on (preferably) or near the ceiling
• on the escape route of each floor level of a household unit
• in every sleeping space or within 3.0 m of a sleeping space door
• in sleep-outs.

Note: The NZ Fire Service recommends installing them in every sleeping and living space.

If a smoke alarm must be located on a wall, install it 100 mm from the ceiling and 600 mm from a corner to avoid dead air pockets.

Do not:

• install in a kitchen, garage or bathroom unless specifically designed for these spaces. Heat detectors can be installed in these spaces instead.
• install close to a heater flue or an extract fan.

Maintenance of smoke alarms

Maintenance of smoke alarms includes:

• monthly testing of the alarm test facility
• annual, in situ cleaning with a vacuum cleaner (no disassembly required)
• replacement every 10 years.