Wireless Fire Detection – it is now possible!

November 13th, 2017

Earlier this year we were contacted by Anson consulting to help install a fire detection system into a large house that was being renovated to be a winery tasting room and accommodation.  The requirement from the Building Certifier based on the Building Code of Australia was for a fire panel and detection system complying with Australian Standard AS1670: Fire detection, warning, control and intercom systems – System design, installation and commissioning.

Sounds simple doesn’t it!  It wasn’t because of a few limitations:

The constraints

This was an installation into an existing building.  The building was originally a 2 storey architecturally designed house.  It was not a commercial building with adequate roof space for services.

The ground floor ceiling was suspended directly from the floor beam.  This meant that travel along the beams was easy but traversing across the direction of the beams required holes drilled through each beam.

Much of the second floor has raked ceilings with exposed beams.  The space between the ceiling is narrow and filled with insulation.

The owner did not want to have the ceiling throughout the house removed and replaced, which would have been required if a conventional detection system was installed.  A conventional detection system has a wire connecting each detector (in series) back to the fire panel.

The Options

At the time of the project there were only two systems that were approved to use wireless detectors.  Only one of these systems also had wireless sounders, also a requirement.  This was the selected system.

The system selected was the Xpander range of wireless detectors and sounders from Ampac Advanced Warning Systems.  More information can be found on the Ampac website. This system has the following components:

Standard addressable fire indicator panel

  • Xpander diversity loop interface (or Radio Hub); this is the base wireless unit that receives the wireless signals and transfers them through to the fire panel as addressable detectors
  • Xpander addressable smoke detectors; these detectors communicate wirelessly back to the Xpander diversity loop interface module
  • Xpander addressable smoke detector with audio visual alarm base; the smoke detector and audio visual alarm both communicate wirelessly back to the Xpander diversity interface module.

There are other devices that can be connected on the system as shown in the following schematic of how the system works

The field devices are all battery powered.  The batteries last 5 years and are continually monitored by the system, so that devices with a low battery are displayed on the fire panel as a fault.

The Design

With wireless detection there is an additional step compared to more conventional wired systems.  And that is the measurement of the signal strength from the Xpander diversity loop interface (or Radio Hub) to the Xpander devices being used.  The signal strength is subject to variation from background noise and walls, floors or ceilings that the signal is to pass through.  This survey is undertaken by staff from Ampac Advanced Warning Systems using a special receiver.

Where signal strength is poor the location for the Xpander device may vary to what would be conventionally selected.  For example in the basement the signal strength was week in the centre of the room and stronger in one quadrant of the room.  As a result the detector was placed in this quadrant.  The spacing must still comply with AS1670 with regard to wall off sets and spacing.

The finished product

The final product was a commissioned fire panel and detection system with minimal impact on the building structure.  While slightly larger devices than a standard system they are still designed to be unobtrusive.

The client was very satisfied with both the way that Anson project managed the project and the minimal impact of the works by Fire & Emergency Services SA in installing the fire detection system.

While this technology is not cheap it does have its place within the market.  So if you have a difficult site that you are retrofitting a fire detection system to and conventional wired system is not feasible talk to us about a wireless detection system