Smoke detectors are classified by their sensing technology, power style, and compliance standards, with photoelectric models widely recommended for residential safety.
Types of Smoke Detectors
Photoelectric (Optical): Uses a light beam to detect visible smoke particles; highly effective for slow, smouldering fires (such as from upholstery or electrical faults) and less prone to false kitchen alarms. 
Ionisation: Uses a tiny amount of radioactive material to detect invisible charged particles from fast-flaming fires; prone to nuisance triggers and largely phased out in modern best practice. 
Dual-Sensor / Combination: Combines photoelectric and ionisation technologies—or pairs smoke sensing with heat/carbon monoxide detection—for comprehensive coverage. 
Heat Alarms: Detects rapid temperature rises instead of smoke; ideal for dusty or humid areas like kitchens and garages where standard alarms cause false alerts. 



Power Styles & Connectivity
Hardwired: Connected directly to a home's 240V mains power supply with a backup battery; usually installed by an electrician.
10-Year Lithium Battery: Sealed, wireless units with non-removable batteries designed to last a decade without replacement.
Interconnected: Linked wirelessly or hardwired so that if one unit detects smoke, every alarm in the building sounds simultaneously.
Specialized Assistive: Features strobe lights and under-pillow vibrating pads designed for people who are deaf or hard of hearing. 

Standards & Compliance
AS 3786: The core Australian Standard for smoke alarms using scattered light, transmitted light, or ionization. 
AS 1670.6 / AS 1670.1: Guides proper installation, spacing limits, sound pressure levels, and placement tolerances relative to walls, ceilings, and air vents. 
Lifespan Limit: Units older than 10 years or using outdated ionization tech generally fail to meet current regulatory standards and require replacement. 

https://www.youtube.com/watch?v=L5bsLuzRBz4 and https://www.youtube.com/watch?v=zrOLxh8GuCU&t=4s


The difference between them is clear. One relies on human supervision while the other does not.