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Secure your nest with Nest Protect - 2nd Generation Smoke Detector
4.9Overall Score
Name: Nest Protector 2nd generation smoke detector
Price (RRP): $189
Manufacturer: Nest

Nest is a Google company dedicated to making your home just that bit more secure. After a few weeks with Nest Protect (smoke and CO detector), 4K Cam IQ and Cam Outdoor with Google Assistant support it is at the top of GadgetGuy’s recommendations.

For reasons unknown, GadgetGuy has never done a review of Nest Protect or other Nest products. Just as well its PR company found out and corrected that. We would never have known just how easy to set up and how effective its products are.

Let’s start with smoke detection 101

At a minimum, it is mandatory to have a battery or mains power photoelectric smoke detector on every level of your home. This includes owner-occupied, rental, relocatable, caravans and camper-vans or any other residential building where people sleep.

There are two basic types of detectors – ionisation alarms and photoelectric. Both types detect smoke as it reduces the amount of light its internal sensor can record. Ionisation is best for flame fires, but it is also more prone to false alarms. Photoelectric is more for smouldering fires that may take a longer time to take hold. Most Australian States will not allow ionisation or combo detectors.

Detectors use either 240V mains-power or a battery. If you use mains power, a licensed electrician must install it. My friendly sparky said that if there is a convenient ‘unswitched’ power source, e.g. not a nearby light fitting in the ceiling it will cost between $100-150 to install. If there is no power nearby, it could cost twice that depending on the power cable run.

It makes the Nest Protect 2nd generation battery version that much more appealing – you can do it yourself – and I did.

New legislation mandates replacement anyway

But by 2022 detectors must have either mains-power or a 10-year tamper-proof, non-replaceable battery (that is the lifespan of these devices anyway). By 2027 you will have to replace all older battery-operated detectors anyway.

Most 10-year battery and interconnected models start at just over $100 compared to the older types from about $30.

There is no real advantage of one power source over the other. If you have lofty ceilings and it’s a pain to change batteries when they start slowly beeping, then use mains. Or, if it is impossible to get mains power to them, use battery. My spies at JB say for retro-fits battery outsells mains ten-to-one.

Smoke detectors are the first line defence – they produce an audible alarm when smoke appears.

Most Australian States are legislating that you have interconnected alarms installed in every bedroom, living spaces (lounge, media room etc.), garage, connecting hallways and paths of exit. You can read more about the location and placement here.

Nest Protect

Interconnected means they all connect either directly (wired) or wirelessly (Wi-Fi or RF).  If one detects smoke, they all sound. Some also link to an alarm, fire control or sprinkler system.

Some have CO sensors (carbon monoxide – the silent killer), heat sensors, humidity sensors, escape path lights, battery test, hush buttons and smartphone apps for remote control. That is where the industry needs to go, but it adds cost to the device.

Review: Nest Protect 2nd generation smoke detector

Website here

What is it?

A well designed, attractive, smoke detector that is an easy retrofit for any smoke detector (battery or mains power). It offers a far greater range of voice and visual alerts (good for vision and hearing impaired) and things like escape path lighting, added sensors and a smartphone app.

Nest Protect
Nest Protect


It is available in two models – either 240V with three AA Lithium L91 replaceable backup batteries or a battery only model with six replaceable AA lithium batteries. At this stage, we must assume fire-authority approval for 10-year use. Both units come with the required batteries so it will be five to ten years before you need to replace them.

The recommended battery is Energiser brand L91 AA lithium batteries with a 2500mA capacity and a 20-year shelf life. The retail cost (Bunnings) of a 4-pack is around $3.75 each ($14.99).