 | |  | | | Wireless interconnect alarms are best suited to retrofit applications where a hard-wired system would be disruptive and necessitate redecorating or the use of trunking. | |
Make the right connection
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| 22 Jan 2010
When a fire breaks out in a dwelling, it might not be possible for the residents to hear a fire alarm located in another room. Neil Perdell, national technical manager with Aico Ltd, states the case for interconnected fire alarms and argues that wireless technology offers the best solution for retrofit and refurbishment applications.
The government’s latest annual fire figures – Fire Statistics, United Kingdom, 2007 – show that, despite 80% of all UK homes having a smoke alarm fitted, there were still 331 deaths from fire in dwellings. The highest fatality rate is for fires which started in the living or dining room and for people aged 80+. The latter is easy to understand – the elderly are less mobile and may not be able to escape in time. But what about fatalities from fires starting in the living room? The most likely explanation is that the occupant was asleep upstairs behind a shut door and did not hear the alarm in time.
A soloutionThere is a simple solution to this and one that is recognised under BS 5839-6:2004 (the Code of Practice for fire alarm systems in dwellings) and Building Regulations – that is to interconnect alarms. When you interconnect alarms, it means that when one unit goes into alarm, all interconnected units also go into alarm mode, sounding throughout the property. As such, interconnected alarms provide an earlier warning and the best chance of escape.
For the physical interconnection of alarms, hard-wiring had been the only way until a few years ago, but now domestic alarm systems using wireless Radio Frequency (RF) signals for alarm interconnection are more and more popular. These wire-free alarm interconnection systems make alarm interconnection easier and cost-effective. The systems use Multi-Sensor, Ionisation, Optical or Heat alarms which are simply slid onto a base containing the RF technology that allows the alarms to interconnect with each other.
Installation is very simple. You will still need to wire each device independently to a permanent mains feed from the nearest local lighting circuit, but this is the only hard-wiring that you will be required to do and is standard practice with all mains powered alarms.
From here, different systems work in different ways. In the case of Aico’s RadioLINK, all the devices intended to be on the system are programmed or ‘House Coded’ together at the time of installation. With over 16.7 million different codes possible, there’s no need to be concerned about alarms being triggered by another system close by. Security systems may use the same frequency as wireless interconnect technology but they will be on a different band and / or be time-restricted in their use of the channel. Car alarms and mobile phones use a completely different frequency so interference is impossible.
RetrofitAs you might expect, wireless interconnect alarms come at a slight premium so may not be suited to standard new builds where hard-wiring isn’t an issue. The main benefit is in refurbishments or when retro fitting as this is when interconnection is time consuming and disruptive (think replastering and redecorating or ugly trunking) and, as a result, costly. Applications that are ideal for such technology include:
a) Existing systems without any interconnection.
b) Existing hard-wired systems which require expansion into additional rooms or areas.
c) Individual dwellings within a block of flats or Houses in Multiple Occupation (HMOs).
d) Connection of remote areas to a central smoke alarm system avoiding the need to run cable for extended distances.
e) New build properties with concrete ceilings.
Wireless interconnect systems are also extremely useful to interconnect different systems within properties – it’s a big advantage in blocks of flats and HMOs. In flats and HMOs where interconnection between dwellings is not required, but wiring from the communal areas is (for early warning purposes), it is easy to provide a simple yet effective system.
Simply ‘House Code’ the alarms in each flat separately and then ‘House Code’ the alarms in the communal areas with, for example, a heat alarm in the individual dwellings. In this way, if a nuisance alarm should occur within one of the dwellings, it will not affect the other residents.
However, if a real fire has occurred, the heat alarm in the dwelling will operate the communal system – and all heat alarms just inside the other dwellings – when sufficient heat has been generated.
When installing a wireless interconnect system however, it’s important not to overstretch the system. By this I mean don’t attach too many alarms to each system. In most domestic properties a realistic maximum number of alarms would be 12. If the property requires more alarms, then it may require a different type of alarm system altogether.
In addition, test to see how far the signal will carry in the property – just because a manufacturer tells you the signal carries over xxx metres, that won’t allow for obstructions such as walls or ceilings which may impede the radio signal path. Also, don’t forget to check the unit is CE marked and has been third party tested to meet EMC, Electrical Safety and Radio Regulations.
The ability to interconnect wirelessly has had other knock on safety benefits, including the capacity to connect to other devices such as Carbon Monoxide (CO) alarms, sprinkler systems and alarms for the Deaf and Hard of Hearing. However, with a number of alarms interconnected in such a set, it’s important to put control switches in place.
Different systems will offer different ways to achieve this, but in the case of Aico’s RadioLINK Professional, a variety of control options are available including a fixed wall switch which allows Test, Hush and Locate features to be incorporated without having to reach up to the alarms; Manual Call Points for use in larger installations and relays to signal to other devices such as a Warden Call Systems are also available.
Wire free alarm interconnection really is a breakthrough in fire detection technology and makes alarm interconnection more likely and more affordable. It also makes a fire alarm system all the more flexible as it becomes simpler to adapt to changing tenants’ needs. If you haven’t tried a wireless interconnect system before, don’t be scared to try it out. We find contractors rarely – if ever – turn back to hard-wiring. | |
 | | | With a number of alarms interconnected, it’s important to use a control switch which allows for remote Test, Hush and Locate functions. | |
 | | | In a RadioLINK Professional system, alarms are slid onto a RadioLINK Base which contains the RF technology to interconnect alarms. | |
 | | | An Optical wireless interconnect smoke alarm being house coded. | |
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