Smoke alarms? Ionising or photoelectric?

Smoke alarms? Are they still an issue?

New houses have been required to install a hardwired smoke alarm for some time. These are interconnected and can alert the occupants of a fire in another part of the house. Very handy.

From 1 July 2016 all landlords are responsible for ensuring operational smoke alarms being installed in all rental properties. The Ministry of Business, Innovation and Employment has the power to investigate and prosecute landlords if smoke alarms are not in place.

Smoke alarm standards require a working alarm be installed on the hallway ceiling, within 3 m of every bedroom door. This is so any sleeping occupant is alerted to any fire within the residence. It is recommended, although not compulsory, to also have one on the ceiling in each bedroom.

If there are no alarms currently any new alarm installed must have a long life, 10-year battery. That avoids the need to replace batteries every 12 months.

Just a word on the terminology here, the device is better described as an alarm, it emits a high-pitched sound that alerts occupants to a fire. Sometimes they are referred to as smoke detectors, but that is a device more used in a large commercial or industrial building where any smoke is reported back to a security station or fire service.

There are two types of smoke alarm: ionising and photoelectric. Each is more sensitive to different types of fire.

Ionising alarms are the most common in New Zealand houses. They are quick to alert with fast burning fires. Ionising alarms do not respond quickly to smouldering fires. Most older smoke alarms are of this type.

They have a significant problem: false alarms caused from cooking or showers. Do not install this type near kitchens or where there is likely to be steam from bathrooms. With false alarms people tend to become sick of the noise and disconnect the battery, rendering them unusable. The house is then left unprotected.

Photoelectric alarms are a bit more expensive. They excel in identifying slow burning fires, and are not as affected by cooking smells or steam as ionising alarms. They are therefore not as prone to being disconnected from their battery. They are slightly slower to detect a raging inferno, but not by a huge amount.

Photoelectric alarms are the smoke alarms recommended to install in a house because of the false alarm issue with ionising type. Best to have one with the long life, 10-year battery.

There are also units which are a combination of both photoelectric and ionising alarms. While the combined unit sound the best of both worlds they can also give false alarms and therefore be disconnected.

Photoelectric smoke alarms are the way to go.

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