Networked Smoke Alarm

The objective of this project are:

• To add a networked smoke alarm within our home automation 19" rack cabinet.
• To see how well our chosen device works, to see if it could be used throughout our next house.
• To see how much power it would take from our 12V DC [PR] UPS.

Design

This project is based around the Aico EI Professional 12V Ionisation Smoke Detector (EI100R). The datasheet (PDF) is available online and shows that this device is happy with a supply voltage of 10.2 to 14 Volts DC. This allows for any voltage drops on long cable runs but, the device uses so little current (standby current = 150 microamps (max), alarm current = 60 mA max, 30 mA min), this is not likely to be a problem.

We plan to connect it with standard 6-core alarm cable as this is cheap we always use wired connections where possible, as they are the most reliable.

This smoke alarm carries the BSI Kitemark to indicate type testing to BS EN14604:2005. It will meet the requirements of Grade D (and exceed the requirements of Grades E and F) as defined in BS 5839: Pt.6: 2004. It carries the CE mark to indicate conformance to Electrical Safety and Electromagnetic Compatibility Directives. Basically there are no legal issue in installing one in your home.

The unit has a built in sounder giving a minimum sound output of 85dB(A) at 3m. Frequency range 2200/2800Hz.

Another reason why we chose this device is that it has both NO and NC relay contacts, rated to 24 Volts/1 Amp resistive. It also supports alarm interconnect, meaning that if one alarm goes off, they all do. This is acheived with a single wire and we will connect them all back at a central point.

We are well aware that there are wireless Z-Wave smoke detectors but, our preference is to always use wired technologies where possible.

Interfacing

This device is going to be connected into our USB I/O board.