Smoke Detection and Fire Alarm Systems

 



 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



 

 

 

 

 

 

 

 

 

 

 


We make sure your fire alarm system is correctly installed and we can also help to ensure you choose the most effective system for your home.

We can help you choose the correct device for each particular part of your home. We can install ionization smoke alarms (which respond quickly to fast flaming fires), photoelectric smoke alarms (which respond quickly to smouldering fires), and heat alarms (which are ideal for kitchens and garages).

We can install interconnectable fire alarm systems, smoke alarm systems, heat alarm systems with (up to 12 smoke and/or heat alarms) and vital secondary power source back-up (e.g. 9v alkaline batteries, 9v lithium batteries, rechargable capacitors, and rechargable lithium cells). See BS 5839 Part 6.

please call us weekdays 8am-5pm

MORE INFO: BS 5839-6:2004 Fire detection and fire alarm systems for buildings. Code of practice for the design, installation and maintenance of fire detection and fire alarm systems in dwellings

When first introduced in 1995, the BS 5839: Pt.6 Code of Practice became the most important set of recommendations ever made on fire safety in the home.

It had an immediate impact on architects, system designers, installers and landlords in the private or public sector, all of whom were required to familiarise themselves with these important recommendations. Landlords in particular needed to abide by these recommendations, as legal liability with regard to ‘duty of care’would undoubtedly become a serious issue should a fire occur in an inadequately protected property.

In short, BS 5839: Pt.6 became the essential guide to providing adequate fire protection in all dwelling types.

In September 2004, the Code of Practice was extensively revised and updated by the publication of BS 5839: Pt.6: 2004 and immediately superseded BS 5839: Pt.6: 1995, which is now withdrawn. The changes therein are important and need to be fully understood and appreciated by all those with responsibility for fire safety in domestic dwellings.

This document is intended as a guide to BS 5839: Pt.6: 2004, highlighting the changes that have come into effect with the introduction of the 2004 edition while still remaining a comprehensive guide to BS 5839 as a whole.

This guide is not intended as a substitute for reading the Code of practice itself. Instead, it’s designed to help make the implications and recommendations of BS 5839: Pt.6 more clearly understood, and to offer advice on how to design, install and maintain a system that meets the requirements, with reference to the 2004 amendments.

At the same time, this guide is designed to help answer the most commonly asked questions about fire detection; for example,‘which types of detector to use and where not to use them’, and to help dispel the myth that alarms are all the same. They are not, as the Code itself is all too anxious to point out.

This latest edition of the Guide has been produced to take on board new developments since the introduction of the Code, both in terms of fire statistics and evolving fire safety technology.

The new edition of BS 5839-6 is the key standard for fire detection in dwellings. It is written to assist the non-specialist in compliance and will help make installations easier to audit. The standard is used by enforcing authorities and contractors, and applies to a range of dwellings of all sizes.
Important new changes include:

* Special design requirements for fire detection and fire alarm systems in dwellings
* Recommendations on domestic smoke alarms
* New technologies including multi-sensor detection, carbon monoxide detection and heat detectors
* Fire warning systems for those with impaired hearing
* Recommendations for limiting false alarms by appropriate system design, system management and improved technology
* An informative annex on how to approach risk assessment and determine system design

The Document Itself

Each clause of the document is now split into 2 parts. Firstly, there is the commentary – in italics – this sets out the reasoning behind what at first sight may appear to be arbitrary recommendations. The recommendations are in normal type, so it is quite possible to simply refer to these alone. The intention is to make the document easier to use; whether it succeeds in this aim is a matter of personal perception.
BS 5839: Pt.6 - An Introduction

BS 5839: Pt.6 is not intended for householders themselves, but to provide guidance and recommendations for architects and other building professionals, enforcing authorities, contractors and others responsible for implementing fire precautions in buildings.

The Code of Practice should not be quoted as if it was a specification and the standard itself warns that particular care should be taken to ensure that claims of compliance are not misleading.

It is also pointed out that compliance with a British Standard cannot automatically confer legal immunity. However, for a landlord or installer, compliance with the latest Code is obviously the best line of defence in any claim made against them.
The Scope of BS 5839: Pt. 6

This Code of practice covers every type of fire detection ‘system’, from a simple self-contained battery smoke alarm right through to major hard wired 24V systems.

The new 2004 Code further takes into consideration “changes in technology, custom and practice, and changes in guidance that supports national building regulations” since 1995.

BS 5839: Pt.6 also covers almost every conceivable type of premises, including:
Bungalows
Multi-storey houses
Individual flats
Individual maisonettes
Mobile homes
Individual sheltered accommodation
Houses in multiple occupation (HMOs)
NHS housing in the community

Both new and existing dwellings are covered.

Communal parts of flats,maisonettes, sheltered accommodation and hostels are not included; neither are caravans.

BS 5839: Pt.6 is primarily concerned with saving lives and reducing injuries. However, it does contain within it recommendations for helping to reduce property damage too. The 2002/3 British Crime Survey, issued by the Office of the Deputy Prime Minister, notes that the mean cost of financial damage caused by a domestic fire is now estimated to be £980 – up a very significant £230 from the £750 estimated in 2001/2. Gross losses to domestic fires have increased by 24% in just one year. This has clear financial implications for the landlord. Good fire safety practice and adherence to the Code can give the best possible early warning of fire and so reduce the financial impact as well as human suffering.
The Grade System

Relates to system engineering, not level of protection.

BS 5839: Pt.6 grades fire detection systems from Grade F up to Grade A. Generally speaking, the greater the fire risk and the more demanding the application, the more comprehensive the system needs to be.

* Grade F - System of one or more battery powered smoke alarms (and heat alarms if required)
* Grade E - System of interlinked mains powered smoke alarms (and heat alarms if required) with NO stand-by supply. The interlink can be hardwired or radio-interlinked. Please note that Safelincs Ltd will not distribute Grade E alarms, as we only recommend alarms with backup batteries.
* Grade D - System incorporating one or more interlinked mains powered smoke alarms (and heat alarms if required), each with an integral stand-by supply. The interlink can be hardwired or radio-interlinked.
* Grade C - System consisting of smoke detectors and sounders (which may be smoke alarms) connected to a common power supply, comprising normal mains and stand-by supply, with central control equipment
* Grade B - Fire detection and alarm system comprising fire detectors (other than smoke alarms), fire alarm sounders and control and indicating equipment to either BS EN 54-2 (and power supply to BS EN 54-4), or to Annex C of BS 5839: Pt.6
* Grade A - Fire detection system incorporating control and indicating equipment to BS EN 54-2, and power supply to BS EN 54-4, installed to BS 5839: Pt.1 with some minor exceptions

The changes from the previous edition are relatively small: Grade A & B now refer to the latest European Standards and there are minor changes in requirements. Grade C now requires central control of the system. Grades E, D & F now have reference to heat alarms in addition to smoke alarms.

Concerned by problems with battery powered units in Grade F, the prescriptive advice in the Code now recommends a minimum five year battery life and batteries that are secured so that a special tool is required to remove them for use in tenanted single storey properties.

As the overwhelming number of residential applications in the UK will fall into the D to F categories, this is the area on which this guide will naturally focus. If you are particularly interested in unusual grades of protection, you are invited to look further at the relevant clauses of the Code.

Of course, installers and specifiers may install a system with greater safety features than laid down in the letter of the Code. For example, rather than a Grade E system landlords might think it prudent to install a Grade D system instead. This is especially true considering the many restrictions that apply to the use of Grade E systems.
Battery Operated Smoke Alarms - Grade F

BS 5839: Pt.6 acknowledges the advantages of the single, battery operated smoke alarm. They are simple to install and offer protection at very low cost. Battery operated smoke alarms conforming to BS 5446: Pt.1 are recommended. Battery operated smoke alarms are suitable for owner-occupied buildings with up to two storeys, as well as for rented bungalows and flats. However, battery operated smoke/heat alarms do have drawbacks. Occupants on a tight budget may not be able to afford to replace the batteries. A significant number of tenants have also been shown to remove the batteries to prevent false alarms or to use in other battery powered devices and then forget to replace them. For this reason, the Code recommends that these alarms should not be used to protect tenants in properties of more than one storey – and even then the batteries should be sealed-in and have a life in excess of 5 years.

As an aside, landlords have now been found liable in cases where tenants themselves have disabled an alarm. For this reason, it is unlikely that landlords will be able to trust tenants to adequately look after the alarms. The Code highlights the fact that battery powered alarms are only suitable for owner-occupied properties if the likelihood is, that batteries will be replaced within five days of a low battery signal.
Mains Powered Smoke Alarms - Grade E

The Code states that interlinked, mains powered smoke alarms are potentially more reliable and are recommended to be installed in existing dwellings occupied by people who are unlikely to be able to change a smoke alarm’s battery.

However, mains powered systems without battery backup (Grade E) have their serious drawbacks: power cuts or the termination of supply for whatever reason disables them totally. They can also be rendered useless by the tripping of a protective device, or even - in some cases - by the fire itself. Householders may also disable them at the mains all too easily if false alarms are a problem. Safelincs Ltd is therefore only offering mains-powered smoke alarms WITH backup battery.
Mains Powered Smoke Alarms with Stand-By Supply - Grade D

The problems outlined above can be overcome by using mains powered alarms that incorporate, within each alarm, a stand-by supply such as a primary or rechargeable battery.The alarms have to be interconnected either through wiring or radio-interlink.

Grade D is required for new, owner-occupied buildings of up to three storeys, two storey rented properties and existing, owner-occupied buildings of more than two storeys. Very large storeys (>200m2) might require Grade B alarm system.

A question remains for landlords - can they be sure that their tenants are paying their electricity bills? Given that many tenants may have low incomes (in many local authorities, 70% or more of all tenants are on subsidised incomes), they may well experience periods of disconnection - and yet the landlord could well be liable if the alarm fails to sound because the tenant has not paid his or her bills! Unfair or not, as the law stands, it obviously makes good commercial sense to ensure that a reliable, high quality back-up battery facility is in place.

The minimum back-up duration recommended is 72 hours, and the Code acknowledges that there could well be circumstances where a longer stand-by period is justified e.g. tenants’ inability to pay their electricity bill.
Fire Detectors supplied with Power from a common Power Supply Unit - Grade A, B, C

More expensive high specification systems can offer connection of all fire detection devices to a common power supply via low voltage transformers, or interlinked fire and security systems. Again, a minimum 72 hour back-up is recommended by the Code. Due to the complexity of A, B and C Grades, we have omitted the descriptions from this short guide.
Levels of Protection - Categories of System

This was previously referred to as ‘type’ of system. It relates to the level of protection afforded by the system.

Within the A - F grades defined earlier, the Code identifies three different categories of protection:

* LD1 - A system installed throughout the dwelling, incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling, and in all rooms and areas in which fire might start, other than toilets, bathrooms and shower rooms
* LD2 - A system incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling, and in all rooms or areas that present a high risk of fire
* LD3 - A system incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling

Apart from the change of name, there are no changes to the ‘Categories’ from the previous version of the code.

It is noted that an LD3 type system is intended to protect escape routes for those not directly involved in the fire and may not save the life of anyone in the immediate vicinity of the fire.

Only by quoting Grade and Category can a meaningful and effective alarm system be specified, e.g. Grade D, Category LD2.

 

tel: 0115 9211556Nottingham Electrician fax: 0115 212121
© 2006 - all rights reserved - 24 Hour Absolute Electric Ltd