Smoke Alarms And Interconnection

Smoke detection in a dwelling is a code requirement with a minimum, and the minimum assumes an occupant who can hear an alarm and leave.

In supported accommodation neither of those is a safe assumption, which changes the specification.

The baseline

**Mains powered** with a battery backup, rather than battery only.

**Interconnected,** so an alarm triggered anywhere sounds everywhere. This is the single most important part of the specification in a shared dwelling, because a resident asleep at the far end of the building is the person the system exists for.

**Positioned** per the code: in each bedroom or in the path between bedrooms and the exit depending on the classification, on each storey, and away from the locations that produce false alarms.

**Photoelectric,** which responds faster to the smouldering fires that occur in dwellings.

The classification that drives the requirement is the subject of [NCC classes and special use accommodation](/blog/ncc-classes-special-use-accommodation), and the number of alarms and their arrangement follows from it.

Where the baseline is not enough

**A resident who cannot hear an alarm.** An audible device alone does not warn them, which means a supplementary device: a strobe, a vibrating pad under the mattress, or both. These are specified for the resident rather than fitted universally, and the power and position for them is provided at build.

**A resident who cannot evacuate unassisted.** Then the system is not only a warning to the resident, it is a warning to whoever assists. Which connects detection to the evacuation strategy in [emergency egress in supported accommodation](/blog/emergency-egress-in-supported-accommodation).

**A resident who may be distressed by an alarm,** where the response to an alarm is part of the support plan and the staff need to know before the whole dwelling is woken.

**A dwelling with staff on site,** where the alarm needs to reach the staff position reliably, which usually means the alarm is integrated with the call system rather than separate from it. The rest of that layer is in [assistive technology in supported accommodation](/blog/assistive-technology-in-supported-accommodation).

False alarms are a real design problem

An alarm that goes off every time somebody cooks or showers gets disconnected, and a disconnected alarm is worse than none because everybody believes it is working.

Which makes placement a genuine design exercise: away from the kitchen and the bathroom door, away from the path of a ceiling fan or a supply air outlet, and out of the dead air at the apex of a sloped ceiling.

In a sealed, mechanically ventilated dwelling the air movement is predictable and designed, which actually makes placement easier, and it is coordinated with [ventilation and air quality in a sealed dwelling](/blog/ventilation-and-air-quality-in-a-sealed-dwelling).

Interconnection across modules

A dwelling made of several modules has alarms in each one, and they have to be interconnected across the module joints.

Which means the wiring crosses an interface that is completed on site, so the connection is designed, documented and tested after installation rather than assumed from the factory test. The joint itself is the subject of [the module joint and how it is sealed](/blog/the-module-joint-and-how-it-is-sealed).

Wireless interconnection is available and it needs the signal path verified through the actual walls of the actual building, not assumed.

Testing and the handover record

The whole system is tested after installation, every device, with the interconnection verified rather than sampled.

Then the record goes into the handover: the device types, the locations, the test date, the interconnection result and the service interval. Which matters because the alarms have a replacement life measured in years and the clock starts at manufacture rather than at handover.

That record and the service schedule belong in [handover documentation and as-built records](/blog/handover-documentation-and-as-built-records), and the ongoing testing obligation sits with the provider from the first day of occupancy, which is part of [commissioning and the first months of occupancy](/blog/commissioning-and-the-first-months-of-occupancy).

MADEmodular / MADEbetter.

Our standards. Discuss a project.