Your apartment has a Clipsal 755PSMA4 – a photoelectric alarm hardwired into the mains, with a 9V battery as a backup for power outages.
The basics
Hardwired with battery backup. The alarm runs on the building's 230V mains supply, so it's always on. The 9V battery only takes over if the power goes out.
Photoelectric sensor. Best at detecting the slow, smouldering fires that often start in soft furnishings or electrical wiring – the kind that can build up overnight before they catch.
Battery type: 9V. A standard 9V (the rectangular kind) – any reputable brand from a supermarket or hardware store will do.
Replace the battery every year. Even if the battery doesn't chirp to indicate low battery, it's best to proactively change the battery annually.
Replace the alarm every 10 years. There's a date stamped on the back of the unit. Once it's past, the unit itself needs replacing, not just the battery.
Changing the battery
If your alarm starts chirping once every 30 seconds or so, that's the low-battery warning – not a fault and not a fire. Swap the 9V battery and it'll stop. It's good practice to change the battery at least once a year even if it hasn't chirped yet.
This 90-second video walks through it:
Step by step
1
Grab a step ladder and a fresh 9V battery. Don't use the kitchen chair – the alarm sits on the ceiling and you want a stable base.
2
Press the tab on the side to release the alarm off its clip. Hold the body of the alarm and press the clip towards the middle of the unit. The unit will fold down from the ceiling plate, still attached by a hinge.
3
Pull the battery out. On the back of the alarm you can use your finger or your nail to pull the battery out.
4
Snap the new battery onto the connector. The 9V only fits one way round – if it's not clicking in, flip it. Settle it into the compartment and slide the cover closed.
5
Click the alarm back onto the bracket. Line it up and fold it up until it clicks into place.
6
Press the test button. A short, loud beep means it's working.
If the chirping continues after a fresh battery, the alarm itself may be reaching the end of its 10-year life or have a sensor fault. Check the date on the back, and if you're unsure, raise it with the building manager.
Testing the alarm
A quick monthly test takes 5 seconds and is the only way to know the alarm will go off when it actually matters.
Press and hold the test button on the front of the alarm for around 3-5 seconds.
You'll hear a loud siren and see a red LED flashing. Let go and it'll stop.
If it doesn't sound, check the battery isn't flat and that the alarm is properly seated on its bracket. If it still won't trigger, contact the building manager.
What the beeps mean
One chirp every 30 seconds or so: low battery. Swap the 9V (see above).
Several chirps in a row, repeating: the alarm has detected a fault. Try a fresh battery first; if it persists, the unit may need replacing.
Loud, continuous siren: smoke has been detected. Treat it as real – check for fire or smoke, and if there's any doubt, leave the apartment and call 000.
False alarms: Steam from the bathroom, burnt toast, or building dust can all trigger the alarm. If you're confident there's no fire, open windows to clear the air and the alarm will reset on its own once the smoke clears. Never disconnect the unit – call the building manager if it keeps mis-triggering.