System Listings

Fire Alarm & Detection

System Overview
Most commercial and industrial premises are nowadays required to have a fire alarm system installed. The system is better described as a fire detection & alarm system, as it's primary function is firstly to detect a fire or fire condition, and secondly to sound audible alarms in all of part of the building. 

At its simplest, the system may be operated purely by Break Glass Units (called a manual system). At it's most complex, the system may have very many different types of smoke, heat other types of detectors spread throughout the building and possibly linked with other buildings.

Is essential that the fire alarms are correctly designed, specified and installed. The system may primarily be designed to protect life (although the premises are may protected) hence reliable, long term operation is essential. 

The design and installation details of the fire alarm should always be agreed with all relevant parties including the Local Fire Office (Fire Brigade), the local District Surveyor (Council), Insurers, site Fire Officers, as well as architects, and structural engineers. All may impose specific requirements relevant to their field.

The over-riding standard for the design of the system is BS5839. This is a comprehensive document and is nearly always cited as the required standard. It includes requirements such as for the detection cabling to be fire proof (hence the common use of MICC in fire alarm systems), battery backup to be provided and a wealth of other design features.  

It is common for the fire alarm system in a building to be classified in accordance with classifications noted in BS5839. These have recently been updated and reference should also be made to BS5839:2002 in respect of the requirements

These are:-

Systems for protecting life.

• Type M - Manual System - A system that relies upon manual Break Glass Units (BGU) being operated by building occupants. If a BGU is smashed then the alarms sound.This system depends upon the presence of people.
• Type L1 - Life 1 - A system with automatic detectors installed throughout the building, including escape routes, stairs, every room, store and void. In addition, BGUs are installed on all exits and between zones. This system will operate even when people are not present.
• Type L2 - Life 2 - A system with automatic detectors installed along all escape routes as well as in high risk areas, such as plant rooms, storage facilities or any other area where a fire would cause a high risk to life. In addition, BGUs are installed on all exits and between zones. This system will operate even when people are not present.
• Type L3 - Life 3 - A system with automatic detection installed only along escape routes and in areas where free passage is essential to protect life. BGUs are also installed at exits and between zones.

Systems for protection property.

• Type P1 - Property 1  -  A system with automatic detectors installed throughout the building, including escape routes, stairs, every room, store and void. In addition, BGUs are installed on all exits and between zones. This system will operate even when people are not present.
  In most cases a P1 system can be taken as having the same cover as an L1 system.

• Type P2 - Property 2 - A system with automatic detectors installed only in high risk areas, such as plant rooms, storage facilities or any other area where there is a high risk of fire. In addition, BGUs are installed on all exits and between zones. Note that an P2 system does not necessarily cover escape routes and may not provide adequate life protection.

The type of system used will depend upon the building however the following arrangements are common. Note that the actual requirements MUST BE VERIFIED these are a guide only.

BS5839 Classification

Other classification also now exist and these are listed in the BS5839:2002

Type of System	Type of premises
M	Small office building with clear escape routes and occupants who know the building
L1	A residential care home or hotel.Or building with specific access/structural risks.
L2	A large complex office building where many people work. An older style building with many corridors and small rooms.
L3	A medium sized office building, retail premises or factory. Where large numbers of people are present, but escape is relatively easy.
P1	A large complex office building where a high risk exists throughout or where a small fire could easily spread and cause extensive damage.,
P2	A listed building or older style premises where fire damage could be expensive.

System audibility is required to be 65db or 10db above background noise. Special requirements existing for buildings housing people who are sleeping such as hotels and care homes etc. The requirements for audibility are not linked with or dependent on, the type of system installed. All areas must have sufficient audibility.

Systems Available and Applications

• Break Glass Units (BGU). A small devices (approx 100x100mm) usually mounted adjacent to fire exits and where an escape route leaves a zone. Smashing the glass will cause a circuit to be either made or broken.

• Automatic detectors. These devices all constantly monitor the surroundings and in the event of a fire condition will cause a circuit to be either made or broken.
  • Smoke Detectors.  May be either optical or ionisation type. These devices detect the actual presence of smoke in the surroundings. Strict rules exist regarding the location and siting of these devices. Very sensitive devices "Very Early Smoke Detection & Alarm ( VESDA) " exist and are used in very high risk areas.
  •  Heat Detectors. May be either fixed temperature or rate of rise devices. The devices monitor the temperature of the ambient air. If the temp rises above a fixed temp or rise too quickly, then an alarm is initiated.
  • Flame Detectors These devices monitor room or areas surfaces and initiate an alarm if a flame is detected
  • Beam Sensors   These devices rely on a infra-red beam being transmitted across a room or space at high level. A sensor picks up the beam and if the beam has been obstructed or reduced in strength (by smoke) then an alarm is initiated.

•  Sounders These devices produce a high volume sound and are located throughout the building. In the event of fire, all the sounders will be energised (unless the fire offices states otherwise) and they will continue until silenced at the panel.
  Several types of sounder exists. The most common type used to be the familiar bell but nowadays, electronic sounders are more common due to the range of types, sizes and tones available. Specific guidelines are included in BS5839 regarding the type of sound and required audibility.
•  Fire Alarm Panel The fire alarm panel is the heart of the fire alarm system. It monitors the detection wiring and devices for faults and operation. If an alarm condition is identified then the panel activates the sounders as well as any other controlled equipment such as remote communicators.The panel is fitted with various indicators and internal buzzers. The zone in which the alarm originates is shown, also with addressable systems, the actual device number and location may be given.
  The fire alarm panel may contain standby batteries (else they are located remotely). The panel may operate on an addressable or conventional basis.
  
  The fire alarm panel must always be situated in a position where the Fire Brigade can easily see and find it (normally by a front entrance). It is hence best to obtain their agreement prior to installation.
  Special arrangements may existing in large complex sites with secondary or "repeater" panels being common in areas such as security desks, second entrances and fire control points.

•  Zoning. All but the smallest building will require segregation as far as the fire alarm system is concerned. The primary purpose of zoning is to aid the identification and to  speedily locate a fire. In essence, the building should be split up into small areas (zones)  in which operation of any devices in the zone will cause a zone indication at the panel. Zone divisions are dependent upon many factors, all detailed in BS5839. However, it is common for zone divisions to be closely related to the building fire compartmentation. A zone should not exceed 2000m²

• Technology. Many, many different forms of technology exist in fire alarm systems, and all manufacturers use their own methods of monitoring and alarm. However, most systems fall into one of two categories:-
  •  Conventional systems. These systems rely on fairly old technology, with a series of radial cables running from the main alarm panel to the devices on each zone. If a device operates then the panel only indicated the appropriate zone. The actual device which operates is not indicated. Such systems are still commonly used for small buildings, or where cheap simple operation is required
  •  Addressable Systems  These systems rely on modern multiplexing technology to individually address each device in the system. When a device operates, the panel indicates both the appropriate zone and the actual device number or even room location. This considerably helps fire location and helps fire crews to get to the point of fire origin very quickly.
    Such systems are wired on by means of one or more loops with only the loop ends being connected at the panel. Obvious cable savings can be made using an addressable system.

•  Remote communication In buildings which may be unoccupied or which may be occupied but unsupervised at night, it is often the requirement of the local fire office to provide a form of remote communication, such as a signal to a central monitoring station or an autodialler which dials a telephone number and repeats a recorded message. Such systems can greatly reduce the time in which the FIre Brigade attends.  

•  Wiring. BS5839 is slightly "wooly" in regards to the type of wiring that is required. It is clear that all sounder cabling (and any other wiring that must function after a fire has been detected) must be be fireproof. However, the detection cabling can be treated differently. It is considered that detection wiring is only needed to detect the fire (ie: until the alarms sound) from then on, strictly speaking, the cabling is not needed.
  In reality however, it is generally accepted that fire resisting cabling is to be used throughout the system for both detection and alarm cabling. MICC cable is considered by some to be the best form of cabling for fire alarm applications, although other more flexible alternatives are nowadays available.

Legislation & Guidelines
The design and installation of a fire alarm system is governed by a range of regulations and legislation. However, in many situations, legislation on covers the objective of the system ie: to adequately protect.

The sure way ensure compliance is to discuss fully with the relevant authorities and to above all ensure full compliance with BS5839.  

British Standards.

Also refer to The British Standards Institution

• BS 5446:Part 1:1990 "Components of automatic fire alarm systems for residential premises". Specification for self-contained smoke alarms and point-type smoke detectors
• BS 4422:Part 3:1990 "Glossary of terms associated with fire. Fire detection and alarm" Terms used to describe the operation of fire alarms systems and specific types of fire detectors.
• BS 7671:2001 "Requirements for electrical installations". IEE Wiring Regulations. Sixteenth edition. This is the all encompassing "Bible" in relation to the design, installation and use of electrical installations and equipment in buildings.It is relevant here due to the need to segregate LV cabling (which fire alarm cables normally are), also for the installation of associated controls and equipment.
• BS 7807:1995 "Code of practice for design, installation and servicing of integrated systems incorporating fire detection and alarm systems and/or other security systems for buildings other than dwellings" Provides recommendations for the integration of a security system with other security systems for use in and around buildings.
• BS 5839:Parts 1 to 8: 2002 "Fire detection and alarm systems for buildings". Comprehensive guide to the design, installation and maintenance of Fire Alarm systems.
  This was updated in 2002 and is now greatly enhanced in its application and scope.
• BS 6387:1994 "Specification for performance requirements for cables required to maintain circuit integrity under fire conditions" Applicable to cables rated at voltages not exceeding 450/750 V and for mineral-insulated cables complying with BS 6207.

Combined Standards

• BS EN 54-1:1996 Fire detection and fire alarm systems.
• BS EN 50130-4:1996 Alarm systems. Electromagnetic compatibility. Product family standard: Immunity requirements for components of fire, intruder and social alarm systems

International Standards

See also IEC search page

• IEC 60331 (1970-01) "Fire-resisting characteristics of electric cables Performance requirements, sample and test conditions, source of heat and test procedure". Has the status of a group safety publication in accordance with IEC Guide 104.
• IEC 60332-2 (1989-03) "Tests on electric cables under fire conditions. Part 2: Test on a single small vertical insulated copper wire or cable"  Specifies a method of testing a small insulated wire under fire conditions when the method specified in IEC 332-1 is not suitable because some small conductors may melt during the application of the flame. Has the status of a group safety publication in accordance with IEC Guide 104.

Legislation

Refer also to the Her Majesty's Stationary Office (HMSO) Government Web Site for further items of legislation and literature.

• Health & Safety at Work Act 1974 - Massive item of legislation which encompasses all aspects of Health & Safety in the workplace. This has been constantly added to over the years. It now comprises and references a whole series of separate regulations and codes of practice documents.
• Fire Precautions (workplace) Regulations 1997
• Fire Precautions Act 1972. Comprehensive act covering all aspects of building construction means to avoid fire. Includes specific requirements for the application of fire alarm systems.
• Factories Act 1962. Act covering working practices, conditions and environmental requirements for the welfare of persons working in industrial environments.
• Offices, Shops & Railway Premises Act 1963. This act includes the legal requirement for premises operators to ensure fire precautions.
• Electricity Act 1989 - In the words of the official HMSO title. "An Act to provide for the appointment and functions of a Director General of Electricity Supply and of consumers' committees for the electricity supply industry; to make new provision with respect to the supply of electricity through electric lines and the generation and transmission of electricity for such supply; to abolish the Electricity Consumers' Council and the Consultative Councils established under the Electricity Act 1947; to provide for the vesting of the property, rights and liabilities of the Electricity Boards and the Electricity Council in companies nominated by the Secretary of State and the subsequent dissolution of those Boards and that Council; to provide for the giving of financial assistance in connection with the storage and reprocessing of nuclear fuel, the treatment, storage and disposal of radioactive waste and the decommissioning of nuclear installations; to amend the Rights of Entry (Gas and Electricity Boards) Act 1954 and the Local Government (Scotland) Act 1973; and for connected purposes."
• Electricity at Work Regulations 1989 - Regulations covering the whole aspect of ensuring that the workplace is safe in regards to the use of electrical equipment. (a part of the H&S at Work act)
• Construction (design & management) regulations 1994 - Another wide reaching set of regulations which cover the whole process of construction safety. It focuses on carrying out risk assessments and altering the design or management process to account for such risks. Again this forms part of the H&S at work act 1974.

Related Links

Links relating to the design and installation of fire alarm systems can be found here

Manufacturers

Most if the above illustrations have been provided by Caradon Gent Ltd to whom thanks is expressed. Other manufacturers are listed here