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September 29, 2010

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New guidance on domestic smoke alarms in Scotland

Changes to Scottish building regulations  – in particular the requirement for increased coverage of domestic smoke alarms – should help contribute to improvements in home fire safety, says Neil Perdell.

Scottish building regulations have had a major overhaul in relation to fire safety guidance and requirements, bringing them into line with BS 5839 Pt.6, the code of practice for the design, installation and maintenance of fire detection and fire alarm systems in dwellings. The new guidance, found in Technical Handbook No.2 Fire, covers the full range of fire safety, but it’s in relation to changes to fire detection that I believe the greatest impact will be made.

And an impact is required. According to United Kingdom fire statistics, Scotland has had a consistently high fatality rate over the years, currently at 11.5 per million population (pmp), compared to an average of 8.7 pmp for the rest of the UK. Whilst the number of non-fatal casualties in 2007 (the most recent annual stats currently available) fell in England, Wales and Northern Ireland, in Scotland the number increased by 5 per cent to 1,700.

It doesn’t make for good reading, which is why the introduction of more stringent fire safety measures in the new Technical Handbook is so welcome. They now provide a greater choice of active and passive fire safety measures and give improved guidance on fire detection and fire alarm systems in dwellings to better reflect the risk.

Increased coverage
One of the changes is the increase in alarm coverage. There is no doubt that the more alarms you have in a property, the quicker a fire will be detected and the greater the chance of escape. The new guidance is at least one smoke alarm, preferably optical, installed in the principal habitable room (normally the lounge / living room) and in circulation spaces such as hallways and landings, and at least one heat alarm in the kitchen, all interconnected. The previous guidance was purely for a smoke alarm in the circulation areas. With 62% of all fires where fatalities were recorded starting in the living room and kitchen, mainly from smoking materials and cooking, this amendment makes good sense.

This is essentially a change from a BS 5839 Pt.6 Grade D, Category LD3 to a Grade D, Category LD2 system. It’s more stringent than building regulations for England and Wales, which disappointingly fell short when revised back in 2007.

The recommendation of optical alarms is also a step forward and good guidance. There are essentially two types of single sensor smoke alarms – ionisation and optical. They both detect smoke particles but in different ways, making them suitable for different areas of the property. Ionisation smoke alarms are particularly responsive to fast, flaming fires where there may be little visible smoke, but they are vulnerable to irritating nuisance alarms caused by cooking vapours from the kitchen, for example. Optical alarms, on the other hand, are particularly suitable for detecting smouldering fires and the dense smoke given off by foam-filled furniture or burning PVC wiring, making them ideal for a lounge. They’re also less prone to nuisance alarms from kitchen fumes.

Clearly the increasing alarm coverage in a property provides dramatically improved protection from fire, but are there any downsides and can they be avoided?

Base control diagram
A new test/hush/locate switch can be wall mounted at a convenient height

With more alarms in a property, there may be more false alarms, failures and associated call out and maintenance expenses for the customer. The obvious answer is to install only the best quality alarms, which may mean paying more. There are some major differences in the alarm build quality between manufacturers, with some doing only the minimum needed to meet the requirements of the standard. Build quality is sometimes not that obvious, so don’t be afraid to ask questions of your supplier on which product they get fewer returns. Furthermore, ensure you only choose alarms that are individually tested, not batch tested – the latter simply isn’t good enough when you’re dealing with a life saving device.

With more alarms to fit, the installation is going to take longer, is going to be more expensive and may be messy, so it’s also worth looking at whether it is simple or time consuming to fit the particular brand of alarms you are looking at.

Control and testing
With a larger alarm system there is a further concern over ‘control’ issues, as there are more alarms that will need to be tested and more that may need to be silenced. It’s also important to be able to locate the precise alarm which originally sounded the warning. Manufacturers are now addressing this. For example, using its new RC technology, Aico has recently introduced a Test/Hush/Locate switch which can be wall mounted at a convenient height. Devices such as these add a very valuable extra measure of controllability to a larger system.

Whilst sensor types are recommended, but not specified, by the Scottish building regulations (apart from heat in the kitchen), it is good to see that optical is the preferred choice in many areas, and that new technology is also addressed such as the multi-sensor fire alarm and radio-frequency (RF) interconnection – both of which make their debut in the regulations.

multi-sensor alarm
Multi-sensor (optical and heat) alarms are now addressed in the new guidance

Multi-sensor fire alarms, which contains two sensors (optical and heat), are recommended in hallways and stairwells adjacent to bathrooms or shower rooms, as they “can significantly reduce the amount of unwanted false alarms”. It should also be noted that the multi-sensor’s response to all fire types is significantly improved when compared with traditional single sensor type units, because it is capable of monitoring two very different by-products of a fire – smoke and heat. As a result, these alarms are particularly advantageous in areas where risks are undetermined or variable, as well as areas where the highest level of protection is desirable.

Radio linked interconnection between hard wired alarms is also referenced for the first time. This works by allowing alarms to be wirelessly interconnected through the use of RF signals. If one alarm on the system is triggered, RF signals are sent to cause every other alarm in the property to sound. This ensures the alarm is heard throughout the property, providing the earliest warning. However, linking systems in communal areas with individual flats is not recommended, due to the perceived risk of false alarms.

It’s good to see Scottish building regulations directly addressing these latest technological developments in fire alarm design and, indeed, embracing them. A valid concern for many installers and specifiers in adopting new technology has been whether they comply with such regulations; now it’s clear in black and white. Add this to the increased alarm coverage, and we should see a genuine impact in Scotland on fire safety in the home.

Neil Perdell is national technical manager at Aico, a wholly owned subsidiary of Ei Electronics. www.aico.co.uk
 

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stag7996
stag7996
January 23, 2016 11:14 am

hi i am a landlord in scotland are these radio linked sensors suitable for me? as i have been told that they all have to be hard wired to each other thanks

narra
narra
May 21, 2016 10:28 pm

stag7996 I also am trying to confirm this. This page would suggest that radio linked (RF) sensors are acceptable…although, I have also heard a rumor about needing to be hard wired.

NigelBrown
NigelBrown
June 7, 2016 9:23 am

stag7996 Hi I run an NICEIC registered electrical installation company in Scotland, we have been asked many times to install radio interlink units. BS5839-6 allows for detectors to be radio interlinked provided that the detector its self is supplied by 230v mains power, I hope that helps.

Moayres
Moayres
July 5, 2016 3:44 pm

Hi, can you tell a rough cost to install in a 3 bed detached bungalow to satisfy legal landlord requirements? Thanks, mo.

BeeBee
BeeBee
November 4, 2019 3:38 pm

I have a comprehensive fire alarm system which is hard wired into my intruder alarm. All the units are 12v from a mains PSU with battery backup.
It appears that none of this will comply with the new regulations.
I’m also concerned about the 10 year replacement costs as well as the waste.

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