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  4. What type of smoke alarm do I need?
  5. Power supply sources
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Power supply sources

There are two main sources of power for domestic smoke alarms: Hard wired/240V smoke alarms and battery operated smoke alarms.

Residential dwellings may use either, however, shared accommodation must be either hard-wired to the mains electricity supply or powered by a non-removable, 10-year long-life battery that is permanently connected to the smoke alarm.

Hard wired/240V smoke alarms

The NSWFB recommends wherever possible a hard wired smoke alarm is installed. This consists of a 240 volt smoke alarm connected to a home's electrical system and it has a battery back-up power supply.

Advantages

  • Considered more reliable in the longer term due to the fact that there are two power sources: domestic supply and a battery backup
  • Early warning - occupants alerted in the shortest possible time
  • Uses a battery to provide back-up power if the AC power fails
  • Models can be interconnected so that the alarms in all connected units sound simultaneously

Disadvantages

  • More expensive
  • Need to be installed by a qualified electrician
  • Not all hard wired/240V smoke alarms have been tested by Scientific Services Laboratories to comply with AS3786

Battery operated smoke alarms

A 9 volt smoke alarm is stand alone and operated only by a battery.

Advantages

  • Easy to install
  • Low battery indication
  • Battery missing indicator

Disadvantages

  • Battery needs to be replaced regularly
  • Not all battery operated smoke alarms have been tested by Scientific Services Laboratories to comply with AS3786
  • A stand alone smoke alarm may not be heard in other areas of the home.

The NSWFB does not recommend any particular type of 9 volt battery, however we do advise that you purchase and install the best quality battery you can afford.

Three most commonly available types of 9V battery

9 Volt Lead

Price range: $2-$5
Limited operation life of up to 12 months
Readily available at most supermarkets, variety stores, convenience stores and hardware stores

NSW Fire Brigades suggested replacement: one to two times per year

9 Volt Alkaline

Price range: $4-$9
Operational life from 18 - 24 months
Readily available at most supermarkets, variety stores, convenience stores and hardware stores

NSWFB suggested replacement: once per year

9 Volt Lithium

Price range: $18-$22
Extended operation life up to 10 years
Available through specialist battery retailers

NSWFB suggested replacement of smoke alarms: once every 10 years, although consider replacing more regularly, as all smoke detectors lose their sensitivity over time. To assist in identifying the age of smoke alarms the AS3786 standard requires a serial number or batch number (Clause4.1(c)). This is usually done as a batch number i.e. 2406 may mean that the product was manufactured in the 24th week of 2006. Some manufacturers place the date of manufacture on the smoke alarm and some now place the expiry date on the smoke alarm. The batch numbers or dates are usually on the base of the smoke alarm near the battery compartment.

Regardless of the type of 9 volt batteries you choose, the NSWFB recommends that they are all tested monthly and that the smoke alarm is cleaned twice per year.