If your smoke alarm is sounding off without warning—and without any visible smoke—it can be frustrating, not to mention disruptive. But while it might seem like your device is malfunctioning, there’s usually a clear explanation behind these false alarms.

In this article, we’ll explain why your smoke alarm keeps going off, explore what causes smoke detector false alarms, and show you how to fix the issue so your alarm works exactly as it should.

Common Causes of Smoke Detector False Alarms

Smoke alarms are designed to be highly sensitive. That’s a good thing—it helps them detect danger early. But it also means certain everyday activities or environmental factors can trigger them unintentionally.

Here are the most common reasons your smoke alarm might go off randomly:

1. Steam or Humidity

Steam from hot showers, cooking, or even a boiling kettle can be mistaken by some alarms as smoke. This is especially true if your alarm is placed too close to bathrooms or kitchens.

2. Dust or Insects

Dust buildup inside the alarm chamber can interfere with the sensors. Likewise, small insects can find their way into the alarm and trigger a false alarm.

Tip: Gently vacuum your alarm every six months to remove dust and cobwebs.

3. Aging or Expired Alarms

Smoke alarms have a limited lifespan—typically around 10 years. After that, the sensors can degrade and trigger false alarms more frequently.

Check the label on the back of your alarm to see when it was manufactured. If it’s approaching 10 years old, it’s time to replace it.

4. Cooking Fumes

Burnt toast, frying oil, or heavy smoke from cooking can easily trigger alarms, especially photoelectric types. This isn’t a fault—just a sign that your alarm is doing its job.

If cooking-related false alarms are common, consider installing a heat alarm in the kitchen instead, such as the ones found in Cavius’ heat alarm range.

5. Low Battery or Power Issues

Many alarms will emit chirps or even go off if their battery is running low or if there’s a wiring fault (in the case of mains-powered models).

Make sure:

• The battery is properly seated
• The battery isn’t expired
• You’re using the correct type (some models require specific battery brands or voltages)

6. Temperature Fluctuations

Rapid temperature changes—such as opening an oven door or letting in cold air—can impact the sensor’s performance, causing a brief alarm.

What You Can Do to Stop the False Alarms

False alarms can usually be resolved with a few simple steps:

• Relocate the alarm if it’s too close to kitchens, bathrooms, or heating/cooling vents.
• Clean it regularly to remove dust and insects.
• Test it monthly using the button—not by lighting a candle or burning food.
• Replace it if it’s more than 10 years old or consistently causing problems.

Need help diagnosing the issue? Visit our smoke alarm troubleshooting guide for step-by-step instructions.

When to Replace Your Alarm

If your alarm continues to sound without cause—even after cleaning and relocating—it may be defective or expired.

You should replace your smoke alarm if:

• It’s more than 10 years old
• It sounds even after battery changes and cleaning
• The test function doesn’t work

Explore our Cavius smoke alarm collection for reliable, modern options that include long-life batteries, wireless connectivity, and smart features to reduce false alarms.

Final Thoughts

If you’ve been wondering, “Why does my smoke alarm keep going off randomly?”, the answer often lies in environmental triggers, placement, or maintenance issues. Fortunately, most false alarms can be resolved without replacing the unit—though older alarms should always be retired when they reach their expiry date.

A properly functioning smoke alarm is one of the most important safety devices in your home. Keeping it clean, updated, and well-positioned ensures it works when it matters most.

For more advice or troubleshooting support, explore our Trouble Shooting Guide, or browse our blog for additional home safety tips.

 

When it comes to protecting your household from fire, smoke alarms are essential. But one of the most common questions homeowners ask is: how many smoke alarms do I need? The answer depends on the size, layout, and design of your home.

In this guide, we break down the ideal number and placement of smoke alarms in New Zealand homes, so you can ensure maximum safety for your family.

Why Smoke Alarm Placement Matters

A single smoke alarm in the hallway is no longer considered sufficient. Fires can start in any room of the house, and thick smoke can spread quickly, reducing the time you have to respond. That’s why having multiple, correctly placed smoke alarms is critical.

Correct placement increases warning time, helps avoid false alarms, and ensures you’re alerted no matter where a fire starts.

General Guidelines for NZ Homes

The New Zealand Fire Service recommends the following:

• At least one smoke alarm per bedroom

• One alarm in the hallway outside sleeping areas

• One alarm in each living area (e.g., lounge, rumpus room)

• One heat alarm in kitchens, laundries, and garages

Minimum Recommendation:

• Small apartment or one-bedroom unit: At least 2 smoke alarms (bedroom and living area)

• Two- to three-bedroom home: 4–6 alarms (bedrooms, hallway, and living spaces)

• Multi-storey home: 1 alarm on each level + alarms in each bedroom and main living areas

Where to Install Smoke Alarms for Maximum Coverage

Choosing the right number is only part of the equation—knowing where to install smoke alarms is equally important.

Best Placement:

• On the ceiling, at least 300mm away from walls and light fittings.

• Centrally located in each room or hallway.

• Away from air vents, windows, and ceiling fans which can affect smoke flow.

Specific Room Guidelines:

• Bedrooms: Place one alarm inside each room.

• Hallways: Install one in the hallway directly outside sleeping areas.

• Living rooms: Essential if people sleep or spend extended time there.

• Kitchens: Use a heat alarm (like this option from Cavius) to avoid false alarms.

• Laundry and garages: Also ideal locations for heat alarms due to increased risk from appliances.

Multi-Level Homes:

• Install at least one alarm on each floor, even if there are no bedrooms on that level.

• Place alarms near staircases or exit points to maximise response time.

Interconnected Smoke Alarms: Why More Homes Are Making the Switch

If one alarm detects smoke, all alarms will sound—giving everyone in the house immediate warning, no matter where the fire starts.

Wireless interconnectivity, such as the Cavius Wireless Family, makes this easy to set up without the need for hard wiring. It’s especially beneficial in larger homes or homes with children or elderly residents.

Tips for Maintaining Proper Coverage

• Test monthly to ensure your alarms are working.

• Vacuum gently every 6 months to remove dust or insects.

• Replace batteries or units as required—check for 10-year battery models for less maintenance.

• Review your layout every few years to ensure your alarm placement still meets your needs (especially if you renovate or extend).

Summary

Here’s a quick summary to help you assess your needs:

• One-bedroom flat: Minimum 2 alarms (bedroom + living area)

• Three-bedroom house: Minimum 5 alarms (3 bedrooms, hallway, living area)

• Two-storey four-bedroom home: Around 7–9 alarms (each room, hallway, staircase, living areas, plus heat alarms in kitchen/laundry)

If in doubt, more is better. It’s always safer to have extra coverage—especially in high-risk areas or larger homes.

When it comes to home safety, few devices are as vital as a working smoke alarm. Yet with so many options on the market, homeowners across New Zealand often ask, “Which smoke alarm is best?” The answer depends on your home’s layout, how you live, and your preferred level of technology.

This guide will break down the types of smoke alarms available, key features to look for, and how to choose the best smoke alarm for your home in New Zealand.

Why Smoke Alarms Are Essential in Every NZ Home

House fires can spread quickly, often when people are asleep. A functioning smoke alarm is your first line of defence, providing early warning and potentially saving lives. In New Zealand, it is recommended that smoke alarms be installed in every bedroom, living area, and hallway, and that they are interconnected if possible.

But not all smoke alarms are built the same. From basic battery-powered units to smart alarms connected to your phone, your choice can make a big difference.

Types of Smoke Alarms to Consider

There are three main types of alarms to choose from. Each type has its strengths, depending on where it’s used:

1. Photoelectric Smoke Alarms

• Best for detecting slow, smouldering fires.

• Less prone to false alarms from cooking fumes.

• Ideal for living rooms, bedrooms, and hallways.

Photoelectric smoke alarms are widely recommended in New Zealand due to their reliability and responsiveness to common residential fire types.

2. Ionisation Smoke Alarms

• Detect fast-flaming fires.

• More sensitive to cooking-related false alarms.

• Less common in NZ homes due to changing standards.

While still available, ionisation alarms are being phased out in favour of photoelectric models due to safety and accuracy.

3. Multi-Sensor Smoke Alarms

• Combine photoelectric and heat detection.

• Offer a broader range of protection.

• Suitable for larger homes or those wanting comprehensive coverage.

These are especially useful for homes with complex layouts or where additional peace of mind is desired.

Key Features to Look For

When comparing smoke alarms, consider the following features:

• Interconnectivity: Alarms that are wirelessly linked will all sound if one is triggered, improving coverage throughout the home.

• Long-life battery or mains-powered: A 10-year battery means less maintenance and fewer false alarms due to low power.

• Test and hush button: Easily manage your alarms without needing to remove them.

• Smart integration: Some models, such as those from the Cavius Smart Range, allow you to receive alerts on your smartphone if an alarm is triggered.

• Water and heat sensors: Especially useful for areas like kitchens, bathrooms, or laundry spaces.

Which Smoke Alarm Is Best for NZ Homes?

The best smoke alarm for your home will depend on your property layout and lifestyle. For most New Zealand homes, a photoelectric smoke alarm with a long-life battery is the ideal choice for general living areas. In kitchens or laundries, you may prefer a heat alarm to reduce nuisance alarms.

If you’re looking for connected home solutions or want to monitor alarms remotely, a system like the Cavius SmartSense Hub and App offers an advanced level of control and real-time notifications via smartphone.

Best Practice Placement Tips

To maximise your home’s safety, follow these guidelines:

• Install one smoke alarm in every bedroom, hallway, and living space.

• Place alarms on the ceiling, at least 300mm away from walls and corners.

• Avoid installing smoke alarms near air vents, ceiling fans, or cooking appliances.

• Use heat alarms in kitchens and garages to minimise false alarms.

• For multi-level homes, ensure each level has at least one alarm.

Maintaining Your Alarms

Choosing the best smoke alarm is only part of the equation. Regular maintenance is essential:

• Test alarms monthly using the test button.

• Clean alarms every six months to remove dust and insects.

• Replace batteries if required or check for expiry dates on 10-year models.

• Replace the alarm unit itself every 10 years, or as recommended by the manufacturer.

Final Thoughts

Finding the best smoke alarm for home use in New Zealand doesn’t have to be overwhelming. Focus on photoelectric technology, interconnectivity, and ease of maintenance. For more advanced options, smart alarms offer extra reassurance.

At the end of the day, the most important smoke alarm is the one that works—so choose wisely, install thoughtfully, and maintain regularly.

For more information about home safety solutions, browse the Cavius product range or explore our news and guides for expert advice.

Whether you’re a business owner or a homeowner, having an emergency fire evacuation plan is vital to keep everyone safe! Evacuation plans let people know when to move and where to go so they don’t get caught up in the panic of an emergency.

It’s easy to build an emergency evacuation plan, so let’s run through how to create one! We’ll also cover why installing photoelectric smoke alarms in the right places is absolutely vital to the success of your new plan.

Why Are Smoke Alarms Important for an Evacuation Plan?

No matter what kind of building you’re planning an evacuation for, the most important part of the evacuation is making sure everyone knows they need to leave. Human beings are often reluctant to believe that they are in survival situations, meaning they can be slow to react, even if they see signs of an emergency.

Alarms are important because they remove that part of the decision-making process. When an alarm sounds, occupants know there is an emergency, and they must get out quickly. This leads to faster evacuation times and ensures that no one is left behind.

To make sure everyone hears the alarm, it’s vital to place smoke or heat alarms throughout the entire building. Make sure you use long-life photoelectric smoke alarms as recommended by Fire and Emergency Services, as these are less prone to false alarms and last for up to a decade.

If you can, opt for a set of interconnected smoke alarms. That way, if one alarm in the building triggers, all of them will go off simultaneously. This means that all occupants learn of the emergency at once, triggering a smooth evacuation.

For Homes

•         Install at least one photoelectric long-life smoke alarm in every bedroom or no more than three metres from each bedroom door.
•         Install at least one photoelectric long-life smoke alarm on every floor of your home to make sure no fires go undetected for too long.
•         Install thermal heat alarms in kitchens, laundries, workshops, and near bathrooms to detect fast-acting fires. In moisture-heavy environments like these, photoelectric smoke alarms are not recommended, as they will trigger false alarms.

For Commercial or Industrial Properties

•         The New Zealand Building Code requires an approved photoelectric smoke alarm to be fitted in every hallway or possible escape route for easy egress.
•         Thermal heat alarms should be installed in shared kitchen and bathroom spaces to prevent false alarms from photoelectric smoke alarms.
•         Carbon monoxide detectors should be installed, especially in industrial settings.

With all that covered, let’s dive into how to create an emergency evacuation plan for your property!

How to Create an Emergency Evacuation Plan

Fires are scary and disorienting, whether they’re happening in your home or your workplace. Smoke, the heat, and structural weakness can all play a role in stopping your escape. Therefore, it’s important to build an evacuation plan that gets all occupants out as quickly and safely as possible.

Build an Evacuation Plan for Your Home

1.     Make sure all your smoke alarms are installed properly, working, and in the right spots in your home.
2.     Establish your first escape route. The best choice is the normal way you come in and out of your home (for most people, this is the front door).
3.     Consider if this way out is locked or blocked in any way. If so, place keys nearby and remove any potential obstacles that could stop your escape.
4.     Account for anyone in your home who might need help getting out, such as young children or anyone with mobility issues.
5.     Do the same for a second and third escape route.

Congratulations, you’ve built your evacuation plan! Make sure to discuss this plan with your family so everyone knows what to do in the event of a fire. House fires act quickly, so it’s vital that everyone is on board with the plan ahead of time.

Build an Evacuation Plan for Your Business

In New Zealand, any buildings that are classified as ‘relevant buildings’ require a pre-planned evacuation scheme. Some examples include buildings where 100 or more people gather, buildings where 10 or more people work, or buildings used for hazardous substance storage.

If you own a ‘relevant building’ you will need to apply for your evacuation scheme through Fire and Emergency Services. You’ll need to show them a variety of documentation to prove your building is fire-safe, including an evacuation training programme and a site plan showing means of escape.

Most evacuation procedures require you to:

•         Know the routes of potential evacuation from all spots in the building.
•         Train your employees with regular fire drills.
•         Assign fire wardens to manage the evacuation and check that everyone made it out.

With all these steps taken, no matter whether you’re a home or a business, you’ll be ready should you ever need to evacuate. Stay safe!

Make sure all occupants know when it’s time to evacuate with CAVIUS smoke alarms.

Our range of photoelectric smoke alarms are designed to last for a decade without replacing the battery. They’re incredibly easy to install and small enough to go undetected while doing their job.

We also offer a range of interconnected smoke alarms to make sure everyone in your home or business knows when it’s time to evacuate. Browse the range of CAVIUS smoke and heat alarms to make sure all goes to plan.

Being a landlord can be incredibly rewarding, but keeping up with the shifting regulations around tenancy can also be tiring. Don’t worry, we’re here to help.

Read on for a comprehensive breakdown of your fire safety responsibilities as a landlord. We cover everything related to NZ compliance, as well as a few extra tips for general fire safety.

Your Legal Obligations as a Landlord

As a landlord in New Zealand, it’s your responsibility to provide adequate system for fire safety in each of your rental properties. Many landlords believe that this obligation starts and ends with installing a couple of smoke alarms, but in reality, there’s a bit more that needs to happen to meet NZ compliance standards.

There are a range of ways that a fire can start in a home. Many of these are your tenant’s purview, but preventing some of these instances is up to you as a landlord. The main thing is to make sure that your smoke alarms are installed according to the following guidelines:

•         At least one long-life photoelectric smoke alarm in each bedroom or within 3 metres of each bedroom door.
•         At least one long-life photoelectric smoke alarm on each level of the property.
•         At least one long-life photoelectric smoke alarm in any caravans or sleep-outs on the property.

Other Ways You Can Prevent Fires on Your Property

The rest of these recommendations aren’t legal requirements, but they are worth heeding if you want to keep your property fire free! Exercising some general fire safety will grant you peace of mind regarding your property and protect the people living there.

•         Inspect your electrical system regularly. Electrical system faults cause a large number of fires and are easily prevented with regular inspections.
•         Provide enough outlets for your tenants. Extension cords and power boxes are often plugged in back-to-back, which can generate a tremendous amount of heat from the electrical resistance. On top of that, the chained extensions can increase the likelihood of shocks or surges, both of which can cause fires.
•         Include a fire extinguisher in the kitchen. Grease fires are notorious for taking over homes quickly, and they can’t be fought with water. But a fire extinguisher can take care of one quickly.

A Tenant’s Fire Safety Checklist

Keep in mind that fire safety comes from your tenant as well! Make sure to run through a tenant’s fire safety checklist with them on move-in day to ensure they know how to look after your property as well as possible. Some things to review with them include:

•         Keeping the stovetop and oven clear of spilt grease or burnt foods.
•         Any batteries in smoke alarms are replaced.
•         Lights are fitted with the right bulb size and wattage.
•         And matches, lighters, or fire-starting tools are carefully monitored.
•         Candles are never burned without supervision.
•         Clothes dryer lint traps are regularly cleaned out.

Choosing Your Smoke Alarms

Per recent changes to NZ compliance laws for tenancy in New Zealand, all new smoke alarms must be either hard-wired into the home or they must be long-life photoelectric smoke alarms. This prevents the batteries from running out, tenants not replacing them, and a blaze igniting without warning.

If there are existing smoke alarms on your property that do not need to be replaced yet, you are not legally obliged to do so. That said, photoelectric long-life smoke alarms are better for your property as a whole, so you might want to do it anyway.

There are also other kinds of alarms suited to different rooms on your property that will prevent false alarms or undetected emergencies. Let’s take a moment to run through your options.

Photoelectric Long-Life Smoke Alarms

A photoelectric smoke alarm works by detecting whether smoke particles have broken a tiny beam of light inside the alarm’s inner chamber. If the beam of light is broken, the alarm sounds, letting occupants know to evacuate the building. Cheaper versions of this kind of alarm can trigger false alarms from insect and dust contamination, so it’s important to invest in high-quality alarms when you can.

To align with NZ compliance these are recommendedrecommend for almost every room in the house, with the exception of rooms that have a lot of moisture, steam, or vapour output. For example, a laundry, kitchen, workshop, or bathroom would be a poor choice for this kind of alarm.

Thermal Heat Alarms

Thermal heat alarms detect fast, flaming fires like grease fires or dryer fires. They monitor changes in ambient room temperature and sound the alarm if there is a rapid, constant temperature increase. They also sound if temperatures reach anywhere above 58 degrees Celsius.

These are ideal for those rooms where you can’t place photoelectric smoke alarms, as they won’t be triggered by moisture or vapour.

Carbon Monoxide Alarms

Carbon monoxide is an invisible, scentless gas that can be lethal when breathed in large enough quantities. It’s generally created by cars and other engines, though there can be other sources in the home. Therefore, it’s important to have a carbon monoxide alarm on your property to keep your tenants safe.

If the carbon monoxide concentration in the air becomes too high, the alarm will sound, indicating tenants must vacate as soon as possible.

Overall, it’s easy to keep your property fire safe and adhere to NZ compliance by investing in the right smoke alarms, having an open conversation with your tenants, and keeping your property up to date. It is worth noting here that Cavius is recalling the Carbon Monoxide alarm 4002 in the interest of optimal safety across the country.

Upgrade to NZ compliance with the world’s smallest smoke alarms.

Browse the CAVIUS range of fire alarms for small, unobtrusive, and highly effective photoelectric smoke alarms that are compliant with New Zealand law.

By checking your smoke alarm battery, placement, and functionality this daylight savings you can have peace of mind knowing that your house is covered for faster detection of smoke or fire.  Plan ahead to protect both your home and family.

Every year the NZ Fire Service attends over 3500 house fires. An even more alarming statistic is that of the 80% of fatal house fires attended, smoke alarms were either not working or not present at all.

Use our 3 simple daylight savings fire safety checklists below:

1. SMOKE & THERMAL ALARM MAINTENANCE (aim to do monthly):

• Check all batteries are working
• Clear of any dust, cobwebs, grease etc.
• Press all test buttons
• Ensure they aren’t obstructed in any way
• Check the alarm’s use-by/expiry date

2. CORRECT PLACEMENT OF ALARMS:

• Mounted to the ceiling, 500mm away from the wall
• For smoke alarms: install in bedrooms, hallways, stairways, and living areas
• For thermal alarms: install in places where fires are likely to start faster such as the kitchen, garage, laundry or workshop
• If you have arched ceilings, place alarm 500mm down from the peak on the ceiling
• If using our Wireless Family alarms, ensure they are within 10m apart and can connect to each other
• See our installation videos here

3. AVOID THE FOLLOWING:

• Leaving electric heaters on at night
• Using electric blankets that are more than 5 years old or appear to be worn out
• Plugging heaters into powerboards (plug into the wall socket instead)
• Covering heating appliances
• Having furniture, curtains, clothes and children any closer than 1m from heaters
• Overloading clothes dryers
• Not clearing lint from clothes dryers
• Leaving fire places uncleared and without a fireguard

You may also want to consider adding a fire extinguisher to your home and establishing an effective escape plan. For a more comprehensive checklist of home fire safety, visit the NZ Fire Service page here.

CAVIUS provides quality products, delivering up to 10 years of consistent detection of smoke and fire.

Learn more about or new Wireless Family alarms which sync with one another meaning that if there is a fire in one room of your house, the other Wireless Smoke Alarms and Thermal Heat Alarms will sound an alarm too.

Find the closest CAVIUS stockist to you.

CAVIUS smoke alarms, daylight savings, Fire safety, house fires, long-life battery, photoelectric, smoke alarm placement, smoke alarms, thermal alarms

Take care of your smoke alarm and it takes care of you.

How to look after your smoke alarms
Give them a vacuum (using the brush setting) or a wipe. It’s that easy. Ensuring there is no dust, cobwebs etc. covering the alarm is so important and will alleviate false alarms.

How often?
Aim to clean your alarms every 2-3 months. This may need to happen more regularly if they are in places that are extra dusty such as garages or workshops.

Why do we clean our alarms?
Photoelectric alarms work by using an optical light, once that light is scattered the alarm will sound; If smoke can’t enter the chamber because it is blocked the alarm simply won’t be able to detect a fire.

 

Other important facts you need to know

• You could encounter false alarms from dust or bugs living inside the smoke alarm chamber if not maintained regularly.
• Smoke alarms shouldn’t be placed in the kitchen as cooking fats and grease can clog it up (a thermal heat alarm is recommended for these areas instead).
• Thermal heat alarms need to be cleaned regularly too.
• Never paint over a smoke or thermal heat alarm as this could interfere with detection.
• Always aim to place smoke alarms in the middle of the room on the ceiling.
• In the kitchen, place thermal heat alarms one step back from the oven and on the ceiling.
• Make sure you have a Fire Escape Plan so you know what to do if a fire happens in your home.
• If you have a large home, or more than one level, the CAVIUS Wireless range of smoke and thermal heat alarms provide added protection by connecting to one another (when one alarm triggers, they will all sound).

 

Fire safety, Phototelectric, smoke alarms, smoke detectors, thermal heat alarms