Here you can find a selection of the industries technical questions that we have answered.

19 May 2020

This new will section use the expertise of our Technical Department to answer the pressing questions that you have asked us. Keeping the industry up to date is a key part of the FIA’s mission to increase the level of awareness and education of everyone involved in the industry; so that we can continue to strive towards becoming more competent and improving fire safety for all.

As we anticipate that this feature will continue to grow because the questions are being directly fed both calls from fire professionals to our Techincal Managers, we have tried to set it out in a common-sense format.

If you have an urgent question please call us on 020 3166 5002 and select the Technical option; or if your question is not urgent please email our technical experts on [email protected]

Our FATQ format:

Sub-sector of the fire industry

Category of question

Specific Question Asked

What training course would expand your knowledge in that area?

Fire Detection and Alarms

Power supplies

What type should the fire panel mains isolator be?

They should be situated in a position inaccessible to unauthorized persons or be protected against unauthorized operation by persons without a special tool, and lockable in both the normal and isolate positions to prevent unauthorized use. (Slot-headed screws would not be acceptable). Contrary to many callers they don’t have to be red.

BS 5839-1:2013 recommended double pole isolation. This is no longer specifically recommended in BS 5839-1:2017.

Advanced Installer
Advanced Designer

Control & indicating equipment (CIE)

Is the panel supposed to have zone LED’s?

Yes. There should be separate “light-emitting indicator” for each zone of the system, for instance, a LED matrix or illuminated mimic diagram. Any repeater panel to be used in the fire and evacuation procedures should also have this type of indication.



When commissioning a system in an office block, I found the sound level in some of the offices to be below 60 dB because the only sounders are in the corridors. Shall I just write a variation?

No. You should refer this back to the designer.

A variation is for intentional departures from a specific recommendation not for errors in design, installation or commissioning. All variations should be agreed by interested parties (e.g. User, Purchaser, Insurer, Enforcing Authority) with justifications.

Advanced Commissioner

Installation practices

Can I use plastic junction boxes or do they have to be metal?

Yes, you can use plastic junction boxes.

BS 5839-1 talks about the integrity of the terminals, not the enclosure. Terminals used to joint cables should be constructed of materials that will withstand a similar temperature and duration to that of the cable. And don’t forget to label the junction box “FIRE ALARM”.

(This doesn’t apply to joints at or within system components such as control equipment, manual call points, fire detectors and sounders.)

Advanced Installer


How often should the fire alarm system be serviced?

The period between successive inspection and servicing visits should not exceed six months. There is currently no relaxation on this. Even if it’s just one day.

Advanced Maintainer


What is the life expectancy of a fire detection & alarm system?

There is no predetermined or fixed lifetime for a fire detection and alarm system as this will depend on the technology used and the environment at the site. In general, control and indication equipment, power supplies, manual call points and heat detectors have a long life expectancy, while other forms of detection will have a limited life expectancy.

Carbon monoxide (CO) fire detectors have a set and predetermined life and should be replaced as per manufacturers’ instructions. Smoke detectors, including beam detectors and aspirating detectors, will have a variable life expectancy that largely depends on the environment at the site.

Generally, equipment manufacturers will be the best guide to an expected lifetime for a particular product in a particular environment. In most situations the expected life of a systems and its components can be extended by carrying out regular and appropriate maintenance.

Further information is available from the FIA Guidance on the life expectancy of a fire detection and alarm system.

 Read our Guidance document

Advanced Maintainer


If indication devices do not comply with EN 54-23 can they be used in a fire detection & alarm system?

Since January 2014 visual alarm devices (VAD) should meet the requirements of EN 54-23. This has led to some confusion regarding the use of combined sounder beacon devices where the beacon element does not comply with EN 54-23. The use of such devices is acceptable while understanding that the beacon element must be regarded as a supplementary visual indicating device (VID) and is not expected to provide a primary alarm warning signal for alerting or evacuating the occupants of the building.

The requirements of any fire detection and alarm system should come from the determinations of a fire risk assessment and the emergency evacuation procedures. If this risk assessment does not identify the need for a VAD then combined sounder beacon bases can provide a supplementary visual indication that will increase the awareness of people to an event. However, manufacturers should make a clear declaration that the device is not to be applied as a visual alarm device as defined by EN 54-23.

For further information refer to the FIA Guidance on the application of primary visual alarm devices and supplementary visual indication devices.


Advanced Designer 

Why do I need to test a multi-sensor detector multiple times?

The majority of multi-sensor detectors are approved to BS EN 54 – X where X is the standard for each individual sensor. i.e. an optical/heat multi sensor device will be approved to BS EN 54 – 7 and BS EN 54 – 5 and can therefore be activated by a single phenomenon, smoke or heat and CO if sensor included.

However not all FD&A systems have the functionality for the separate signals from each detector element, heat/smoke/co to be logged when a test is carried out with simultaneously presented test mediums.  It is therefore recommended in BS 5839-1 that, where the design of the detector permits, each individual detector element of a multi-sensor detector be tested separately to ensure correct functionality.

BS 5839 – 1 2017 + corrigendum 45.4 j) 3) states that each sensor should be tested individually but does allow the sensors to be tested simultaneously PROVIDED the system can annunciate in some manner that each sensor channel is operational. The test should establish that each element is detecting the applicable phenomena and that its “level” is annunciated by the system.  Due to the interaction between the sensor channels required for the detector to signal an alarm the “level” of each sensor does not necessarily have to be taken above the alarm threshold level as per individual type detectors.

Where the detector or system design is such that individual sensors cannot be tested individually, for example certain types of conventional multi-sensor detectors, the primary sensor alone may be tested.

A multi-sensor device should be tested depending upon the number of sensors it has. i.e. 2 sensors 2 tests, 3 sensors 3 tests.  It is accepted that there is no requirement for an additional test, to test the device with all test medium simultaneously, as the risk of all sensors being individually operational failing to operate as a combined alarm is minimal.  

Full guidance on testing is given in the FIA guidance note Testing Multi-sensor Detector. It must be ensured that if any parameter settings have been changed to enable testing they MUST be reinstated on completion of the testing.


What is the service life of a fire extinguisher?

There’s is no set limit in the UK standards for the service life of a fire extinguisher.

Manufacturers will give a warranty period for new extinguishers as you would expect for all new products.

In many situations (including the following) the UK’s extinguisher maintenance standard, BS 5306-3, recommends that the extinguishers are condemned, effectively ending their service lives:

  • certain types of corrosion
  • dents or gouges to the body
  • any plastics lining being split, lifted or detached
  • UV degradation of plastic components
  • the extinguisher not being able to be maintained due to parts being unobtainable

Additionally, as with all maintenance, there is always an economic decision to be made before undertaking maintenance, particularly when it requires work and/or parts that are costly in relation to the value of the equipment. For extinguishers, common examples of such occasions include the time of the extended service or overhaul. In such circumstances, replacement may be the preferred option.

Lastly, it is also worth reminding the reader that sometimes perfectly serviceable extinguishers may nonetheless need replacing as they may be entirely unsuitable for their intended use.

Service & maintenance of portable fire extinguishers


Will the CE mark replace other third-party certification marks on portable fire extinguishers?

It is important to note that the CE Mark is not a quality mark. In relation to the Pressure Equipment Regulations, it only signifies that the product meets essential safety requirements in relation to its pressurisation. The recognised quality marks e.g. the BAFE mark, BSI kitemark and the LPCB mark should continue to be recognised as the appropriate quality marks.

 F-Gas Certification

What is the purpose of the F-Gas Regulations?

EC Regulation 517/2014 is to contain, prevent and reduce emissions of Fluorinated Greenhouse Gases (F-Gases) covered by the Kyoto Protocol in order to combat climate change. This regulation replaces the original regulation EC 842/2006.

In the case of fire protection users of these systems have numerous obligations to prevent leakage of F-Gas extinguishants, especially for any equipment containing 5kg CO2 equivalent or more of agent.

There are many obligations that apply to fire protection systems suppliers and maintenance contractors, especially relating to the use of appropriately qualified personnel and certification of companies.

F-Gas Certification for individuals 

For more on F-Gas Certifications click here 


Emergency lighting FAQs

Automatic Self Testing Emergency Lighting - Can I leave site during a full duration test?

Yes, as this is the purpose of the automatic testing is to test the system. However, good practice may be considered to stay on site during a full test to enable the emergency lighting technician to witness any failures in the system and to be on hand to reinstate power if needed. It needs to be ensured that the emergency lighting light levels during the test are adequate for the duration. A risk assessment should be undertaken to determine whether leaving site would maintain a safe environment, e.g., in an unpopulated building this might be acceptable. Emergency lighting maintenance

How do I know that my emergency lighting light levels are correct?

Suitable verification in line with BS EN 60598-2-22. The key view is the quality of the product in liaison with appropriate design documentation. DIALUX / RELUX are suitable context to achieve appropriate design. Ongoing maintenance must be achieved including a likely update of annual luminaire cleaning and physical suitable calibrated cosign corrected lux meter prEN 50172 suggests 5-year physical check. BS 5266 may uplift the view to annual check.  Emergency lighting maintenance

How often do I have to change batteries on a standalone fitting and a central battery system?

The product standard requires a minimum 4-year design life for self-contained emergency light fittings and 10 years for above 500kW 3-hour Central Battery Powered systems.

However, depending on the volume of testing (charge/discharge of the batteries) best practice would be to schedule battery replacements more frequently (<4 years) and upon regular service visits.

Note: BS EN 60598-2-22 product standard and BS EN 50171 for the CPS sits with the requested life of cells. Good practise would be given to identify a scheduled process of battery replacement within a suitable timed period. Emergency lighting maintenance

When a fault is located when does it need to be repaired?

All faults should be recorded and registered in the logbook and with the maintenance provider. If alternate devices are functional and safely working, then a risk assessment may consider that the repair can wait until the next service visit. However, in a well populated / potential risk area then early fast repair is more appropriate. Emergency lighting maintenance

What type of products should we use?

Suitable compliant devices (to BS EN 60598-2-22) with the appropriate 3rd party certification such as BSI. Emergency lighting design

What minimum emergency light levels do I need to achieve at fire alarm system equipment?

The minimum light level needed at components such as manual call points and disabled refuge outstations is 5 lux. These are deemed as low difficulty as only a button needs to be pressed.

The minimum light level needed at the CIE is 15 lux. This is deemed medium difficulty as a person might be required to read text printed on the CIE and information on the zone plan. Emergency lighting design

Should a fire risk assessment specify the category of a system when requesting fire detection and alarm system to be installed?

Yes, when requiring a new or modified system. The commentary of clause 5 of BS 5839-1:2013 says “BS 5839 does not recommend which Category of system needs to be installed in any given premises.

The various system Categories need to be regarded as a “menu”, from which purchasers, users, specifiers, enforcing authorities, insurers or system designers may select a suitable system for any building. However, Annex A provides information on the Categories of systems that are typically installed in various types of premises.” When it comes to risk assessment it is the responsibility of the risk assessor to specify the category of system required to provide the coverage appropriate to the risks when requesting a new fire detection and alarm system. This is also the case when asking for any modifications to existing systems.

Unit 9: Fire risk assessment and procedures
Advanced Designer

If my premises have sprinklers do I need portable fire extinguishers?

In a nutshell yes! Sprinklers are extremely effective and reliable in controlling an established fire, so limiting the extent of fire spread and often fully extinguishing it. However, experience shows, that at an earlier stage than sprinklers operate, a small fire can often be extinguished by trained staff using portable extinguishers, so, to an even greater extent, limiting fire damage and also preventing water discharge from sprinklers. There is a requirement under UK fire safety legislation 1 for portable fire extinguishers to be provided “where necessary”. In the view of the FIA, it is rare to find situations where portable fire extinguishers are not needed

1 In England and Wales, the Regulatory Reform (Fire Safety) Order 2005. In Scotland, The Fire (Scotland) Act 2005, in combination with the Fire Safety (Scotland) Regulations 2006. In Northern Ireland,  the Fire and Rescue Services (Northern Ireland) Order 2006, in combination with the Fire Safety Regulations (Northern Ireland) 2010.

Introduction to fire in buildings


Why do I need external emergency lighting?

Short Answer: If there is no external lighting during the hours of darkness, your eyes take time to adjust to different light levels. If there is no external lighting during the hours of darkness, your eyes take time to adjust to different light levels. When moving from one light level to near darkness, i.e. exiting a building in an emergency in low light levels, the human eye takes some time to adjust to the new lower light level. Without the external lights, people would have difficulty finding their way. Previous editions of BS 5266-1 allowed the use of street lighting to illuminate the external areas. With local councils turning off street lights at certain times to save money and energy. It’s not always possible to rely on street lighting. The current edition of BS 5266-1 says that if street lighting relied on it needs to be reassessed to make sure that they will still be illuminated at all times the premises are in use.

Emergency Lighting Foundation & Design


When carrying out a fire risk assessment, should the fire risk assessors enquire about the history of false alarms?

Yes, it’s a useful snapshot of the health of the fire alarm system. The history of false alarms can provide a good indication of how well the premises are being managed. Several of the same types or causes of false alarms can indicate an underlying issue with the management of premises and activities being carried out or deficiencies in the design or maintenance of the fire alarm system. A high level of false alarms can also impact on fire safety by causing compliance of occupants in relation to the need to evacuate, identifying a high level of false alarms in the risk assessment can help the duty holder take appropriate action. Any false alarm investigation and the outcome of that investigation should be done in conjunction with the fire detection and alarm maintenance company.

In carrying out fire risk assessments, consideration should be given to the use of staff alarms in the case of buildings with a significant number of smoke detectors, so that false alarms from smoke detectors do not result in the unnecessary summoning of the fire and rescue services (and, possibility, unnecessary evacuation of the buildings). However, care should be taken to recommend the use of staff alarms only when there is a sufficient number of trained and competent staff to investigate safety, and when resulting delay in evacuation the event of a real fire would not undermine the fire strategy of the building (or any part of the building). Suitable procedures are necessary to limit the investigate period and to ensure that there are means for investigating staff to report a fire. The procedures must be such that those investigating a fire are not placed at risk.

Unit 9: Fire risk assessment and procedures


Is the building bound to satisfy the Regulatory Reform, if plans have been approved under national building regulations?


If plans have been approved under national building regulations, the building, once completed, is bound to satisfy the Regulatory Reform (Fire Safety) Order (or equivalent legislation in Scotland and Northern Ireland)?


The scope of physical fire precautions required under national building regulations throughout the UK is similar to that of the Regulatory Reform (Fire Safety) Order (or equivalent legislation in Scotland and Northern Ireland), but it is not identical. For example, national building regulations do not require the provision of portable fire extinguishers, but these are normally required under legislation after the building is completed. Also, the ongoing legislation makes numerous requirements in relation to management, which is outside the scope of national building regulations.

In England and Wales, there is a statutory requirement for the building control body to consult the fire and rescue service before approving plans for a building to which the Fire Safety Order will apply. This requirement only applies to certain classes of building in Scotland and is not replicated in Northern Ireland, where voluntary consultation normally occurs to a variable extent.

In any case, the building control officer is not obliged to accept the comments of the fire and rescue service. Moreover, there is not complete certainty that the building will be constructed in accordance with the approved design. Even a completion certificate is not conclusive evidence in this respect.

Accordingly, it is not unknown for the first (and sometimes later) fire risk assessments (or audits by the fire and rescue service) to identify breaches in fire safety legislation in a relatively new building for which plans were approved under national building regulations.


Can normal passenger lifts, under any circumstances, be used for evacuation of disabled people?

Short answer No.

Long answer:

In most circumstances, if a fire strategy incorporates the use of lifts for the evacuation of disabled people, only modern firefighters’ lifts, or properly designed evacuation lifts, conforming to the recommendations of BS 9999, should be used.  Even an old-style “fireman’s lift” would not normally be suitable as it would not, for example, incorporate the duplicate power supplies required in the case of a modern fire-fighting or firefighters’ lift.  Similarly, normal passenger lifts, which are not designed for use during a fire in a building, will not normally be suitable for evacuation of disabled people, as they will not have the duplicate power supplies and appropriate communications facilities incorporated in firefighters’ lifts and evacuation lifts.  In addition, they might be designed to return to the ground and come out of service when the fire alarm system operates.

Nevertheless, there may be circumstances in which, on the basis of a risk assessment by a competent person with a sound understanding of the relevant aspects of lift technology, a normal passenger lift might be considered for the evacuation of disabled people.  This is acknowledged in BS 9999, which provides two good examples of circumstances in which a non-evacuation lift might be used for evacuation of disabled people.

The first example is that of a building equipped with sprinklers, with significant compartmentation or smoke control.  The second example is that of a very large building, in which a non-evacuation lift, which is remote from an initial fire, might be used for evacuation of disabled people.

A possible example of the second case described in BS 9999 is that of a multi-storey shopping mall.  If there is a fire within one of the shops, it might well be the case that a normal passenger lift, located some considerable distance along the mall, would remain unaffected by the fire for a considerable period of time, so enabling disabled people evacuated from the shop of fire origin and the associated smoke control zone, to be evacuated to a lower mall, from where final exits can be reached.

The same principle might apply in, for example, sheltered housing, in which most fires will occur within flats, but these fires are unlikely to affect the power supplies to normal passenger lifts within the common parts, certainly in the early stages of the fire.  Accordingly, NFCC guidance on fire safety in specialised housing notes that, based on a careful risk assessment that takes into account the likelihood of failure of power supplies to the lift, and entry of smoke into the lift shaft, normal passenger lifts might be used for evacuation of disabled people under the supervision of staff or the fire and rescue service.


Can acoustically-actuated door release units be used in premises in which people sleep?

Short Answer: No

Long answer: Acoustically-actuated door release units are designed to hold a self-closing fire door in the open position, against the action of the self-closing device.  (The self-closing mechanism can also be swing-free so that it only becomes active when the fire alarm system operates.)  The door is caused to close by the self-closing device when the hold-open device releases the door in response to the audible signal from the building’s fire alarm system. 

The circumstances under which such devices may, or may not, be used was, at one time, a matter of controversy.  However, this was largely resolved with the publication of BS 7273-4 in 2007.  That code of practice provided some suggestions as to where “Category B” hold-open devices, which do not fail-safe in the event of a fault on the fire alarm system, might be used.  This includes acoustically-actuated door release units.

BS 7273-4 was revised in 2015.  The current, revised version sets out, in a normative annexe, which forms part of the recommendations of the code of practice, those situations in which Category B hold-open devices (now described as “standard” actuation devices) may be used.  The only restrictions on the use of these devices are the following:

In a compartment wall separating buildings;

Within the enclosures of any stairway in an hotel, boarding house, hall of residence, HMO, hostel, residential care building, a building containing apartments, a place of public entertainment or similar premises (excluding hospitals, for which BS 7273-4 refers to Department of Health and NHS Scotland guidance);

Within the enclosures of a stairway that is the only stairway serving a building (or part of a building) which has more than one storey above or below the ground storey (other than in dwellings).

Accordingly, the use of acoustically-actuated hold-open devices would be acceptable for holding open, for example, cross-corridor doors and bedroom doors in care homes and cross-corridor doors in hotels.

In England and Wales, Approved Document B under the Building Regulations recommends compliance with all parts of BS 7273 that apply to actuation of other systems.  In Scotland, the Technical Handbooks that support the Building (Scotland) Regulations impose certain restrictions on the use of any hold-open devices on fire doors in certain locations, including doors opening into fire-fighting shafts.

BS 7273-4 CPD (We are not running this CPD Session currently)

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