Smoke detectors, or ‘smokies’, are imperative for safety in the home. Gary Busbridge looks at the standards and installation requirements for these life saving devices.

When you consider the devastating effects of house fires, it is easy to understand why smokies are now mandatory throughout Australia. Just recently we saw the effects of a fire in a nightclub in South America where over 200 people died and many more suffered burns and smoke inhalation. A smokie wouldn’t have helped in this situation, but it clearly shows that a fire acts quickly and dangerously, providing little time for escape.

Many house fires happen as a result of accidents, and occasionally this is when we are sleeping. Did you realise that when we’re asleep we lose our sense of smell? Without the high-pitched shrieking of a smokie, we may well sleep through the only period of time that would allow escape. The house could be a raging inferno in a matter of minutes and razed to the ground in less than a quarter of an hour.

Many home owners use battery powered smokies, and this is quite acceptable, except that you must remember to change the batteries every year. This is their major weakness, however, and is the reason that new buildings are required by regulation to be fitted with mains-powered smokies. There are some battery powered smokies on the market that use lithium batteries and these would last up to 10 years without changing the battery. Preferably you should use a mains-powered smokie with battery back-up. Why? It’s always there and ready to provide that necessary warning about smoke. All these devices must pass Australian Standards as mandatory requirement before being offered for sale and as such are all acceptable for your home.

There are two types on the market, Photoelectric and Ionisation. Simply put, Ionisation smokies respond faster to smaller smoke particles, such as those from burning paper, straw or wood.

Photoelectric smokies respond faster to larger smoke particles, such as those produced from burning foam, rubber, plastics and other synthetic materials. These are just the type of materials used in your home nowadays for furnishing, bedding and electrical appliances.

For ultimate protection it is probably wise to consider where the smokies are to be positioned and use a combination of both ionisation and photoelectric smokies. With mains-powered devices it is possible to provide an interconnection between them all, so that if one does detect smoke, then all the others will activate and sound the warning simultaneously in all locations within the building.

Besides the warning shriek, there could be a “chirping” sound that can be emitted occasionally. Usually this is to remind us all that the battery needs replacing or that there is a fault in the device. Both the shriek and the chirp are normal when they are making the noise for the purpose intended but there can be times when these sounds are not warranted or wanted.

As such, there are a number of facts to know about smokies, so that problems don’t arise. As stated above, the common complaints with smokies are nuisance tripping, alarming without the presence of smoke, and chirping for no apparent reason. In most instances it is not the smokie that is at fault.

The smokie must be located in an area that allows smoke to reach it and also kept away from steam, fumes or dust that may cause it to activate. As with buying a new home, the words “location, location and location” spring to mind.

Ionisation smokies need to be kept away from sources of cooking fumes, oven cleaner, solvent and paint vapours. If the smokies need to be mounted in areas where these fumes may be present then a photoelectric version should be used. Whereas Photoelectric must be located away from areas that would be near bathrooms, where steam may be present, and dust contamination.

The connection of the mains powered smokie must be made to an Active not a switched Active. Not a surprise really, but this can be an issue in dubious quality installations, as the smokie then has to rely on its battery to continue operating until the next time the switch is turned on. Eventually the battery runs flat and the chirping will begin.

All smokies must pass Australian Standards and this also includes passing electro-magnetic interference (EMI) testing. Electrical noise or spikes can be generated by many of the electrical accessories in common use and these can be the cause of continued nuisance tripping.
•    External electrical noise which may be generated by large industrial installations and then passed through the power supply lines
•    Automatic security lights can also provide this noise because of the switching relay incorporated.
•    Inductive loads, such as fan, heater and light units, heaters or airconditioners being switched on or off also can provide this noise.
•    The switching of fluorescent lighting can also be a  source of noise, especially if a starter is getting old or you have cheap fittings which may not have quality components within.
•    Photovoltaic, or solar, systems can also provide a noise which will be seen by the smokie. Keep the smokie away from below a solar system.
This type of problem can be a very difficult to diagnose because it may happen only at random times of day. Also some electrical accessories may be of poorer quality than others within the installation which doesn’t help with problem resolution.

Contamination of the smokie is a constant source of problem. It may happen at installation or anywhere in its life and is affected by the environment in which it is installed. A build-up of fats, cooking oils, lint, dust or insect detritus in the sensing chamber are the common issue.

Depending on the weather, there may also be condensation, which in combination with the contamination can cause nuisance tripping or chirping. This combination can affect the printed circuit board and its components quite badly. Once the noise starts it may only stop when the condensation dries up, or worst case it will be stopped when the unit is replaced completely. If issues with condensation in an Ionisation smokie continue then it may warrant a change to Photoelectric.

It is so important to keep the smokie clean from dust and debris. It is a good habit to provide a clean up of the smokie on a regular basis. Be aware that poor installation may allow a certain amount of dust or moisture to be forced into the smokie by the back-draft from the ceiling space. Keep the number and size of holes used to pass wires through from the ceiling space to a minimum.

A lot of stuff to remember, but to successfully install any smoke detector you must understand the complexity of the environment and location. To install without due regard for these extraneous issues, well, there is every likelihood that it will result in customer dissatisfaction and unnecessary servicing calls because it is thought that the smokie is faulty.