Interconnection is no longer optional on a New Zealand new build, but the standard does not tell you which method to use to achieve it. NZS 4514:2021 permits both wireless and hardwired interconnected smoke alarm systems, which leaves the actual decision to the builder, electrician, or specifier on each individual job.
Why This Decision Matters More Than It Used To
Under the current Acceptable Solutions for Protection from Fire, every qualifying alarm in a new residential build needs to sound together as a single network. Before this requirement, a standalone alarm in each room was enough, and the interconnection method was not a specification decision at all. Now it is, and getting it right the first time avoids a rework once walls are lined and trades have moved on.
Hardwired Interconnection: What It Offers
Hardwired systems connect alarms with a dedicated cable run, typically coordinated with the electrician during the rough-in stage. The main advantage is a fixed, permanent connection that does not rely on a wireless signal, which some specifiers prefer for larger homes or multi-storey builds where wireless range could be a concern.
The trade-off is coordination. Cable runs need to be planned alongside the rest of the electrical rough-in, and any late change to alarm positions, which happens more often than anyone would like on a live build, means revisiting wiring that may already be run.
Wireless Interconnection: What It Offers
A wireless system uses radio frequency communication between units instead of a dedicated cable run. Units can be positioned, and repositioned, without needing to coordinate a wiring change, which gives a lot more flexibility if the layout shifts during the build or if a late-stage design change moves a wall or a doorway.
This is increasingly the preferred choice for standard residential builds specifically because it removes a dependency from the electrical rough-in schedule. Weighing up wireless vs hardwired smoke alarm NZ builder options usually comes down to this flexibility, since a wireless specification can be finalised later in the build process than a hardwired one, without risking compliance.
Making the Call on a Specific Job
Choose hardwired when the build is large, multi-storey, or has unusual layout features where wireless range or interference could genuinely be a concern, or when the electrical scope is already extensive enough that an additional low-voltage run adds little complexity.
Choose wireless when flexibility matters, the build timeline has any uncertainty around final room layouts, or the job is a standard residential new build where keeping options open for as long as possible is worth more than a marginal cost difference.
Consider a mixed approach where most of the home runs on wireless interconnection but a specific zone, such as a converted garage workshop, benefits from a dedicated heat alarm on the same wireless network rather than a separate hardwired run.
What We See Working Well on Site
Builders and electricians who have switched to wireless interconnected systems for standard residential work consistently report fewer late-stage changes causing rework, since repositioning a wireless unit takes minutes rather than requiring an electrician back on site. For larger or more complex builds, a hybrid approach, hardwired for the main structure with wireless extension into converted or added spaces, often gives the best of both.
Supporting the Decision With the Right Product
We supply the CAVIUS wireless interconnected range specifically for this kind of standard residential specification work, alongside heat alarm variants for garages and other nuisance-prone zones that need to sit on the same network. Our NZ Building Code page sets out the full Acceptable Solutions context if you want to confirm what a specific project requires before locking in a method.
If you are speccing a run of builds rather than a one-off, it is worth getting in touch with our trade team to talk through volume pricing and support for ongoing projects.
The Bottom Line
Both wireless and hardwired interconnection meet the current standard, so the right choice comes down to the specifics of the job rather than a one-size-fits-all rule. For most standard residential builds, wireless gives the flexibility to make late changes without a wiring rework, while hardwired still has a place on larger or more complex projects.