A new report into smoke alarms on the New Zealand market has found that they are not all created equal.
The institute took 21 different alarms - six photoelectric and the rest ionisation - and tested them at the BRANZ fire laboratory in Upper Hutt.
Both types picked up a blazing fire fairly quickly but when a test was done with a smouldering fire the results were disturbing.
The ionisation alarms took significantly longer to go off - some up to 10 minutes - and some didn't go off at all.
Ionisation alarms work by using a radioactive source to ionise the air, creating a current. Minuscule products of combustion, like carbon dioxide and carbon monoxide, disrupt that current, setting off the alarm. Ionisation alarms work well during a fast burning flaming fire, but cooking and steam can set them off - that's why they're no good in a kitchen or bathroom.
Photoelectric alarms work by using a beam of light. When smoke particles scatter that beam the alarm goes off. Photoelectric alarms are the best at picking up smouldering fires and perform almost as well as ionisation alarms during flaming fires.
The head of the Consumers' Institute, David Russell, says to make sure they weren't getting atypical samples alarms were bought from different shops.
"There will be people who are under a false sense of security because the test clearly shows that some alarms work better than others," says Russell.
The Fire Service installs ionisation alarms in 10,000 at-risk houses a year. But after years of promoting ionisation alarms the service now agrees that photoelectric alarms are better.
The problem is the price. Ionisation alarms are currently half the price of photoelectric ones.
The debate about the merits of the different types of smoke alarm is not new.
But what is new is that the Australasian Fire Authorities Council - and that includes New Zealand - has this week decided to tell people they should buy photoelectric alarms over ionisation ones.
Hotels and apartments in Australia, Britain and Europe are being made to switch to photoelectric alarms, and overseas the two types are now similar in price. Alarms that combine the two detection methods are also becoming popular.
But while all sides agree photoelectric alarms give you the best chance of surviving a fire the experts still say it is better to have an inferior alarm than no alarm at all.
You can see how your smoke alarm rated at the Consumer's Institute website .
