Conventional Fire Alarm System

In a Conventional Fire Alarm System, a number of call points and detectors are wired to the Fire Alarm Control Panel in Zones. A Zone is a circuit and typically one would wire a circuit per floor or fire compartment. The Fire Alarm Control Panel has a number of Zone Lamps. The reason for having Zones is to give a rough idea as to where a fire has occurred. This is important for the fire brigade and of course for the building management. The accuracy of knowing where a fire has started is controlled by the number of Zones a Control Panel has and the number of circuits that have been wired within the building. The Control Panel is wired to a minimum of two sounder circuits which could contain bells, electronic sounders or other audible devices. Each circuit has an end of line device which is used for monitoring purposes.

Addressable Systems

The detection principle of an Addressable System is similar to a Conventional System except that the Control Panel can determine exactly which detector or call point has initiated the alarm. The detection circuit is wired as a loop and up to 99 devices may be connected to each loop. The detectors are essentially Conventional Detectors, with an address built in. The address in each detector is set by DIL switches and the Control Panel is programmed to display the information required when that particular detector is operated. Additional Field Devices are available which may be wired to the loop for detection only i.e., it is possible to detect a normally open contact closing such as sprinkler flow switch, or a normally closed contact opening. Sounders are wired in a minimum of two sounder circuits exactly as a Conventional System. Loop Isolation Modules are available for fitting on to the detection loop/loops such that the loop is sectioned in order to ensure that a short circuit, or one fault will only cause the loss of a minimal part of the system.

Analogue Addressable Fire Alarm Systems

Analogue Addressable Fire Alarm Systems are often known as Intelligent Fire Alarm Systems. There are several different types of Analogue Systems available which are determined by the type of protocol which they use. The bulk of standard Analogue Detectors available are fairly limited in functionality as the Detectors can only give output signals representing the value of detected phenomena. It is left up to the Control Unit to decide whether there is a fire, fault, pre-alarm or other. With a true Intelligent Analogue System each detector effectively incorporates its own computer which evaluates the environment around it and communicates to the Control Panel whether there is a fire, fault or if the detector head needs cleaning. Essentially Analogue Systems are far more complex and incorporate far more facilities than Conventional or Addressable Systems. Their primary purpose is to help prevent the occurrence of false alarms. With the Analogue Addressable System, up to 127 input devices i.e.: Smoke Detectors, Call Points, Heat Detectors, Contact Monitors and other interface devices may be wired to each detection loop. In addition to the 127 Input Devices, up to 32 Output Devices such as Loop Sounders, Relay Modules and Sounder Modules may be connected. Analogue Systems are available in 2, 4 and 8 loop versions which means large premises can be monitored from one single panel. Isolator units should be connected between sections of detectors as described for Addressable Systems.

Wireless Fire Alarm System

Wireless fire alarm systems are an effective alternative to traditional wired fire alarm systems for all applications. They utilise secure, licence-free radio communications to interconnect the sensors and devices (smoke detectors, call-points, etc.) with the controllers. It is a simple concept, which provides many unique benefits and is a full analogue addressable fire detection system without the need for cable.

(1) Housing Act 2004

All housing is subject to the Housing Act 2004, which introduced The Housing Health and Safety Rating System (HHSRS or the Rating System) – a risk assessment approach that identifies 29 potential hazards (including fire) to be considered in domestic accommodation. The Act is enforced by the Local Housing Authority and includes the licensing of houses in multiple occupation (HMOs), management regulations for HMOs, and home information packs.

(2)  The Regulatory Reform (fire safety) order 2005

The Fire Safety Order covers general fire safety in England and Wales, whereby fire and rescue authorities (and other enforcing authorities) have a duty to enforce fire safety in non-domestic premises, with a few exceptions. For instance, the Order applies to the common areas of houses of multiple occupation, flats, maisonettes and residential care premises.  The Order does not apply to private homes, including individual flats in a block or house,

Under the FSO, there are a number of fire safety duties placed on the “responsible person” which is typically the employer or the person either in “control of” or the owner of the premises, such as a private landlord. 

(3) The Smoke and Carbon Monoxide Alarm (England) Regulations 2015

Under this fire safety legislation, private landlords in England are required to have at least one smoke alarm on every level of their property. A working carbon monoxide alarm should also be installed in any room with a solid fuel-burning appliance (such as an open fire or wood burner). Private landlords also must make sure the alarms are working at the start of each new tenancy.

It is important to note that the 2015 legislation does fall slightly short of the recommended fire safety outlined in BS 5839 pt. 6, so it is recommended that landlords abide by the former.

(4) Building Regulations: Approved Document B Volume 1

Applies to new builds, materially altered dwellings, loft conversations and certain building extensions for standard dwellings and any other work that requires a building warrant.

Approved Document B specifies that:

“Buildings are to be designed so that there are appropriate provisions for early warning of fire, and apt means of escape in the event of fire”

In section 1 “Fire detection and fire alarm systems” it specifies that all new dwelling houses should be provided with a fire detection and fire alarm system to at least a Grade D Category LD3 standard (as outlined in BS 5839-6:2004). It also recommends that, should occupants/tenants of the dwelling house be at special risk of fire, it is more appropriate for private landlords to provide a higher standard of protection, e.g., by implementing additional detectors or an LD1 system.

The Regulatory Reform (Fire Safety) Order (RRO) 2005 provides a safety standard for all commercial buildings including offices, retail shops, factories, warehouses, and shopping centres. Specifically, section 13-1a of the regulation states that premises are “equipped with appropriate fire-fighting equipment and with fire detectors and alarms”. Any Fire Alarm & Detection Systems fitted to a commercial building must comply with British Standards 5839-1 and be installed in accordance with BS7671 17th Edition Wiring Regulations.

Current UK fire alarm regulations state that all commercial buildings must have an appropriate fire detection system in place. What this implies is that, in the event of a fire, the commercial building must be equipped to detect the threat at the earliest and warn the occupants to evacuate immediately.

According to the regulations, anyone who holds a controlling position is considered responsible for implementing fire safety and meeting the standards set out in the RRO. This may include the owner, employer, manager, occupier, or anyone who has a certain level of control over a part of the commercial building.

In the event of non-compliance, and if the issue is non-serious, the fire authority will send a formal notice and provide practical advice on improving the situation. If a genuine risk to human lives is discovered, the authorities might issue a notice prohibiting the commercial building from being used.

In serious offences where there is a complete disregard for human life, the people responsible may be fined or imprisoned. Minor penalties include a fine of up to £5,000 and major penalties range from unlimited fines to 2-year imprisonment.

A fire detection and fire alarm system, although it can do nothing to reduce the incidence of fire, can help to lessen the resultant loss in terms of injury to occupants or damage to property. However, the system needs to consider the ability of the persons it is designed to protect and their ability to react to the warning and to ensure time for escape that it is intended to give them is feasible. This is regarded as just one component of a properly engineered approach to fire safety. 

In order to maximize the cost benefit of a fire detection and fire alarm system, it is essential that the system design is appropriate to the fire risk. Importantly, the design of any fire detection and fire alarm system installed in accordance with BS 5839 needs to be based on a good understanding of fire risk within the premises. 

A high fire risk demands high reliability in the early detection of fire and warning of occupants, regardless of where the fire starts, and high reliability on the part of the system to operate correctly when required; a low fire risk might not justify the cost, complexity and extent of such a system. For example, at one extreme, the single occupant of an existing small bungalow might be adequately protected very simply if the occupier installs one battery-power smoked alarm, whereas the risk to which the families in a six-storey house in multiple occupation (HMO) are exposed to would warrant a more complex and comprehensive system.

It is therefore essential that the design of the system, particularly in respect to factors such as the number of detectors, placement of detectors and the form of power supply, considers the following probabilities: 

1. The probability of fire occurring.
2. The probability of injury or death of occupants if fire occurs.
3. The Probability of the systems operating correctly at the time of a fire.
4. The probability of early detection and warning of occupants in the event of a fire.

All fire service safety testing, maintenance or installation works should be delivered in accordance with the latest UK fire safety standards and in accordance with BS 5839, the BS EN 54 series of standards for fire detection and fire alarm systems and BS 9999.

BS 5839-6: 2019 section 25.1 states that the testing of a fire alarm does not require any specialist knowledge. However, it may be appropriate for a competent person who has knowledge of the standards and an understanding on how to apply them, to carry out testing and maintenance, especially if there is a complex system in place.

The FSO defines a competent person as follows:

“A person is to be regarded as competent for the purposes of this article where he has sufficient training and experience or knowledge and other qualities to enable him properly to assist in undertaking the preventive and protective measures. Such competent persons would be suitably trained and qualified fire alarm maintenance contractors, ideally with some form of identifiable third-party accreditation.

The periodic inspection and servicing of the system needs to be carried out by a competent person with specialist knowledge of fire detection and alarm systems. BS 5839-1 advises that this should include knowledge of the causes of false alarms. The person carrying out the work should have sufficient information regarding the system and adequate access to spares. 

BS 5839-1 states “Periodic inspection and servicing are necessary so that unrevealed faults are identified, preventive measures taken, false alarm problems identified and addressed, and that the user is made aware of any changes to the building that affect the protection afforded by the system. The last of these points is particularly important. “

BS 5839-1 recommends simply periodic inspection and testing of the system, rather than specifying an exact frequency at which this should be carried out. The code recommends that the period between successive inspection and servicing visits should be based upon a risk assessment, which accounts for the type of system installed, the environment in which it operates and other factors that may affect the long-term operation of the system. However, the code does re-commend that the period between successive inspection and servicing visits should not exceed six months. If the risk assessment shows the need for more frequent inspection and servicing visits, the code recommends that all interested parties should agree an appropriate inspection and servicing schedule. 

BS 5839-1 recommends annual testing of all manual call points and automatic fire detectors. The test recommended for each type of detector is a functional test. For example, it would not be sufficient to rely purely on measurement of digital values at the control equipment of an addressable system (although the code also recommends that these values be checked every twelve months). 

If quarterly servicing is adopted, 25% of all detectors can be tested at the time of each quarterly visit, so that all detectors are tested on an annual basis. If six monthly servicing is adopted, either all detectors will need to be tested at the time of each alternate visit, or 50% of the detectors would need to be tested at each service visit. 

The code provides recommendations on other measures that should be carried out on a twelve-month basis, including a visual inspection to confirm that all readily accessible cable fixings are secure and undamaged, and confirmation that the entire “cause and effect” program of the system is correct.

Periodic inspection and testing:

The period between visits to undertake inspection and service should be based upon a risk assessment but the maximum period between visits should not exceed six months.

• The logbook should be inspected.
• A visual inspection should be made to check whether structural or occupancy changes have been made that require changes to the fire detection and fire alarm system.
• False alarm records should be checked, and relevant action taken if necessary.
• Batteries should be checked and tested.
• Control panel functions should be checked and tested.
• Fire alarm devices should be tested.
• Facilities for automatic transmission of alarm signals to an alarm receiving centre (ARC) should be checked after advising the ARC of the proposed actions.
• All fault indicators and circuits should be tested and checked.
• Printers should be tested.
• Checks and tests recommended by the manufacturer should be carried out.
• Outstanding defects should be reported, the logbook completed and servicing certificate issued.
• The recommended period between successive inspection and servicing visits should not exceed six months.

Quarterly inspection of vented batteries:

• Vented batteries should be examined by a person with relevant competence and should be topped up if necessary.

Inspection and test of a system over a 12-month period:

• The switch mechanism of every manual call point should be tested.
• Every automatic fire detector should be examined and functionally tested. This includes, but is not limited to; smoke detectors, resettable heat detectors, optical beam smoke detectors, aspirating fire detection systems, carbon monoxide fire detectors and flame detectors.
• All fire alarm devices (both visual and audible) should be tested.
• Certain filament lamps should be replaced.
• Radio fire detection and fire alarm system signal strengths should be checked.
• Visual inspection of readily accessible cable fixings should be undertaken.
• The “cause and effect” programme should be checked.
• The standby power supply capacity should be checked.
• Other annual checks and tests recommended by the system component manufacturers should be undertaken.
• Outstanding defects should be reported, and the servicing certificate issued.
• As this is labour-intensive servicing, it is recommended that the work can be spread over two or more service visits during each twelve-month period.

Non-routine attention:

The arrangements in the above section, inspection and servicing are intended to maintain the system in operation under normal circumstances. However, from time to time, the fire alarm system is likely to require non-routine attention, including special maintenance. Non-routine maintenance includes:

• Special inspection of an existing fire alarm system when a new servicing organization takes over servicing the system.
• Repair of faults or damage.
• Modification to take account of extensions, alterations, changes in occupancy or false alarms.
• Action to address an unacceptable rate of false alarms.
• Inspection and test of the system following a fire.

BS 5839-1 recommends the appointment of a ‘responsible person’. This term is defined in the code as the person having control of the building and/or premises, whether as occupier or otherwise, or any person delegated by the person having control of the building and/or premises to be responsible for the fire alarm system and the fire procedures. The code recommends that this person be given sufficient authority to carry out the duties described in the code, and that this person should normally be the keeper of the documentation recommended in the code. The primary duty of the responsible person is to ensure that: 

• The system is tested and maintained properly. 
• Appropriate records are kept. 
• Relevant occupants in the premises are aware of their roles and responsibilities in connection with the fire alarm system. 
• Necessary steps are taken to avoid situations that are detrimental to the standard of protection afforded by the system. 
• Necessary steps are taken to ensure that the level of false alarms is minimized. 

The implications of these objectives relate to testing, maintenance, keeping of documentation and proper system management. The responsible person should also ensure that the control and indicating equipment is checked at least once every 24 hours to confirm that there are no faults on the system. It is also the responsibility of the responsible person to ensure that suitable spare parts for the system are held within the premises; the code gives guidance on the nature of these.

The user should also ensure that the system receives non-routine attention (usually by specialists) as appropriate.

Once the system is handed over to the user, there will be a need for it to be maintained, so that it continues to provide the protection that it was designed to give. This will necessitate regular testing by the user and periodic servicing by specialists. 

The routine testing recommended in BS 5839-1 is not intended to overlap significantly with the benefits afforded by system monitoring. The testing that is recommended is very basic in nature, and it can be implied from the recommendations of the code that it really only has two principal functions. 

The first of these is to ensure that the system has not suffered some form of catastrophic failure, such as total power failure or major circuit failure. In pursuit of this confirmation, the code recommends that, every week, just one manual call point should be operated. The purpose of this test is only to ensure that the control equipment is capable of processing a fire alarm signal, if one occurs, and can provide an output to fire alarm sounders. If there is a facility for transmission of fire alarm signals to an alarm receiving centre, it should also be ensured that the signal is correctly received at the alarm receiving centre. To avoid any confusion between the weekly test and a genuine fire alarm signal, the code now recommends that the duration for which fire alarm sounders should operate at the time of the weekly test should not normally exceed one minute. 

The second, but more subsidiary, objective of the weekly test is to familiarise occupants with the fire alarm signal. For this reason, the code specifically recommends that the weekly test should be carried out during normal working hours. It is also recommended in the code that the test be carried out at approximately the same time each week. In systems with staged alarms, incorporating an ‘Alert’ and an ‘Evacuate’ signal, the two signals should be operated, where practicable and sequentially in the order that they would occur at the time of a fire. This is to minimize the chance of confusion between the ‘Alert’ and ‘Evacuate’ signals. 

In some premises, certain occupants may work only at times other than that at which the fire alarm is tested. An example would be permanent night shift workers. To ensure that these employees are also made familiar with the sound of the fire alarm system, the code recommends that, in such cases, an additional test(s) be carried out at least once a month to ensure the familiarity of these employees with the fire alarm signal(s). 

While the objective of the weekly test is not to test all manual call points at any particular frequency, as a form of “bonus”, the code recommends that a different manual call point should be used at the time of every weekly test. The purpose of this is to capitalize on the test to give some opportunity to identify a defective manual call point. Since, however, this is merely something of a bonus, the code acknowledges that, for example, in a system with 150 manual call points, each manual call point will only be tested by the user every 150 weeks. To ensure the rotation in testing manual call points, the code recommends that the identity of the manual call point used in the weekly test should be recorded in the system logbook. 

If an automatically started emergency generator is used as part of the standby power supply for the fire alarm system (i.e., the relaxation in battery capacity offered by the code is adopted), there will be a need for routine testing of the generator. The code recommends that, in this case, the generator is started up once each month by simulation of failure of normal power supply and operated on-load for at least one hour, after which fuel tanks should be left filled, and oil and coolant levels should be checked and topped up as necessary. 

If vented batteries are used as a standby power supply, a monthly visual inspection of the batteries and their connections should be carried out. In particular, electrolyte levels should be checked. In practice, the use of vented batteries in fire alarm systems is now uncommon, but occasionally it occurs in premises that contain large battery banks for other purposes (e.g., some power stations).