Why linking them matters
A lone alarm only helps whoever hears it. In a two-storey house, or one with bedrooms at opposite ends, a fire can grow for a while before a single alarm behind a closed door wakes anyone. Linked alarms close that gap: the moment one detects smoke, they all sound.
Linking doesn't change where alarms belong. Fire and Emergency New Zealand's recommendation is still one in each bedroom, hallway and living area.
New homes, rentals and homes you own
New homes. C/AS1 Second Edition Amendment 1, effective 28 July 2025, requires each household unit to have at least a Type 1 domestic smoke alarm system complying with NZS 4514, and names interconnected alarms to NZS 4514:2021 as the minimum fire safety system. An acceptable solution is one way of showing Building Code compliance, so your designer and the council's consent process settle the detail. The previous edition could only be used for consent applications lodged before 1 August 2026.
Rentals. Tenancy Services' rules set the type of alarm (photoelectric with a long-life battery, or hard-wired) and where it goes. A landlord can use a linked set, as long as it meets those rules. The smoke alarm rules page has the detail.
Homes you own. Outside a building consent, we couldn't find a rule that makes an owner-occupier link existing alarms. It's still one of the most useful upgrades for a larger or multi-level house.
Radio-linked or wired?
| Radio link | Wired link | |
|---|---|---|
| How they talk | Each alarm sends a radio signal to the others | A cable runs between the alarms |
| Power | A long-life battery, or the house's power with a battery backup | The house's power, with a battery backup |
| Suits | Existing homes with finished ceilings | New builds and renovations with the ceilings open |
| Who we'd use | Battery-only units: you can put them up. Anything on the house's power: a licensed electrician | A licensed electrician |
| Watch for | Signal range in big or solid-walled homes, so check every alarm sounds | Matching brand and model, since linked alarms generally only talk to their own range |
Adding them to an older home
The easy route is radio-linked long-life alarms, which need no new cable. Mount one in each bedroom, the hallways and the living areas, pair them as the maker's instructions say, then press one test button and walk the house to check every unit sounds.
If you already have hard-wired alarms, an electrician can often link them by wire or radio, or swap them for a linked set from one maker. Different brands usually won't talk to each other, so plan to replace the whole set together.
Fire and Emergency New Zealand says its Home Fire Safety Visits don't include installing interconnected alarms for code compliance, and it suggests contacting a licensed electrician for that work.
What you can do, and what we'd hand over
You can
- Mount and pair battery-only radio-linked alarms, following the maker's instructions.
- Each month, press an alarm's test button and check the whole house sounds.
- Replace a linked set together when it reaches its replacement date.
Leave to a licensed electrician
- Connecting alarms to the house's power.
- Running a wired link between hard-wired alarms.
- A system for a new build that has to meet the building consent.
What we'd fit
In an existing home, we'd go straight to radio-linked long-life photoelectric alarms from one maker, one in every bedroom, hallway and living area, and check they sound together. In a new build or a gutted renovation, we'd have an electrician put in a hard-wired interconnected system meeting NZS 4514:2021 while the ceilings are open.
Want a specialist to sort it?
Tell us the job and your postcode. We match the licence-checked local electrician who does this kind of work, and they call you. No ring-around, and your number goes to them alone.