Yes — installing a carbon monoxide (CO) detector is straightforward DIY work that any NZ homeowner can do. You don't need a licence to fit a detector, and doing so is one of the most important safety steps you can take if you have gas appliances in your home. The tricky part isn't the installation; it's knowing where to put it and which product to choose.
Why Carbon Monoxide Is So Dangerous
Carbon monoxide is a colourless, odourless gas produced when fuels like natural gas or LPG burn incompletely. Faulty or poorly ventilated gas heaters, cooktops, water heaters, and flued appliances can all produce dangerous CO levels. Because you can't see or smell it, CO poisoning can happen without warning. WorkSafe NZ lists CO as a serious workplace and home hazard, and the same risks apply in residential settings.
Is Installing a CO Detector Restricted Work?
No. Fitting a battery-operated or plug-in CO detector is not restricted work under NZ law. You can buy one and install it yourself without any licence.
However, if you're hardwiring a detector into your home's electrical system, that is restricted electrical work and must be carried out by a registered electrician. Check the Electrical Workers Registration Board (EWRB) to find a licensed electrician if you want a hardwired unit.
Importantly, if you suspect your gas appliance is the source of a CO problem — for example, a detector keeps alarming — do not attempt to service or repair the appliance yourself. Gas appliance servicing and repair is restricted work under the Gas Act 1992 and must be done by a licensed gasfitter registered with the Plumbers, Gasfitters and Drainlayers Board (PGDB).
Choosing the Right CO Detector
Look for a detector that meets EN 50291 (the European standard widely accepted in NZ) or UL 2034 (the US equivalent). Both are recognised as suitable for residential use in New Zealand. Key things to check:
- Electrochemical sensor — the most reliable technology for home use
- Audible alarm of at least 85 dB
- Digital display showing CO levels in parts per million (ppm) — useful for spotting low-level build-up
- Battery backup if you choose a mains-powered unit
- Replacement date — most detectors have a sensor life of 5–10 years; replace the whole unit, not just the battery, when it expires
You'll find a good range at Bunnings and Mitre 10. As a rough guide, expect to pay somewhere in the range of $50–$150 for a quality standalone unit, though prices vary by brand and features.
Where to Place Your CO Detector
Placement matters. CO is slightly lighter than air but disperses fairly evenly, so placement is more flexible than smoke detectors. Follow these guidelines:
| Location | Recommendation |
|---|---|
| Height | Fit at head height (roughly 1–1.5 m) or as per manufacturer instructions |
| Near appliances | Within the same room as gas heaters, flued appliances, or water heaters |
| Bedrooms | At least one detector outside sleeping areas — CO poisoning often happens at night |
| Avoid | Within 1.5 m of cooking appliances (false alarms from cooking fumes), damp bathrooms, or direct sunlight |
| Garages | If your garage is attached, fit one near the connecting door |
Always read the manufacturer's installation guide — it will specify the exact mounting height and clearances for your model.
Step-by-Step: Fitting a Battery or Plug-In Detector
- Choose your location using the guidance above.
- Insert batteries or plug into a power outlet, following the manufacturer's instructions.
- For wall-mounted units: hold the bracket against the wall, mark the screw holes with a pencil, drill pilot holes (use a stud finder first), and secure the bracket with the supplied screws and wall plugs.
- Clip or twist the detector onto the bracket.
- Test the unit using the test button — the alarm should sound within a few seconds.
- Record the installation date on the detector or in a home maintenance log. Set a calendar reminder to replace it before the sensor expires.
Maintaining Your Detector
- Test the alarm monthly using the test button.
- Replace batteries annually (or when the low-battery warning sounds).
- Never paint over the detector or cover the sensor vents.
- Replace the entire unit at the end of its rated sensor life — typically shown on a label on the back.
- Have your gas appliances serviced regularly by a licensed gasfitter. BRANZ recommends annual servicing of flued gas heaters as good practice.
When to Call a Professional
Call a licensed gasfitter (find one via the PGDB or on tradedirectory.co.nz) if:
- Your CO detector alarms — evacuate first, then call
- You notice soot or yellow/orange flames on a gas appliance (a sign of incomplete combustion)
- Your gas appliance hasn't been serviced in over 12 months
- You're installing a new gas appliance or modifying gas pipework — this is always restricted work
Call a registered electrician if you want a hardwired CO detector installed.
Safety note: If your CO alarm sounds, get everyone (including pets) out of the house immediately, leave the door open, and call 111 or your gas supplier's emergency line. Do not re-enter until emergency services or a licensed gasfitter has cleared the property.
Sources & Further Reading
- WorkSafe NZ — Carbon Monoxide Hazards
- Plumbers, Gasfitters and Drainlayers Board — Find a Licensed Gasfitter
- Electrical Workers Registration Board — Restricted Electrical Work
- BRANZ — Home Maintenance and Safety Guidance
- MBIE Building Performance — NZ Building Code
- Energywise — Safe and Efficient Home Heating
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