- What are the fire alarm requirements for New – Build properties?
- What is a Grade D system?
- What do LD2 and LD3 mean?
- What are the requirements for existing properties?
- What is a Fire Risk Assessment?
- If I install an LD2 level of cover can this remove my responsibilities to conduct a Fire Risk Assessment?
- What do I need to do to address the requirements of ‘special needs’ people or groups?
- What types of sensor are available?
- How do Aico Ei Ionisation and Optical Smoke Alarms work?
- What are the advantages and disadvantages of both sensor types ?
- How do Aico Ei Heat Alarms work?
- Which Alarm should I use where?
- Where should alarms be sited?
- How many do I need?
- Where shouldn’t the Aico Smoke Alarms be sited?
- Will they always work?
Standards & Regulations for the Domestic Fire Alarm Systems
- The BS 5839: Pt.6: 2004 recommends that a new-build property consisting of no more than 3 storeys (less than 200sqm per storey) should be fitted with a Grade D, LD2 system
- The Building Regulations in England,Wales & Scotland recommend that BS 5839: Pt.6 should be followed, but as a minimum a Grade D, LD3 system should be installed.
- The Building Regulations in Northern Ireland require a Grade D, LD2 system to be installed, with smoke alarms fitted in the escape routes and the main living room and a heat alarm in the kitchen
The BS 5839: Pt.6 standard places different alarm types into Grades, simply described as follows:
- Grade A – a system of detectors and sounders with control and indicating equipment (a panel & perhaps call points)
- Grade B – a similar system to Grade A with some minor amendments.
- Grade C – detectors and sounders, or smoke alarms, with some control features.
- Grade D – mains smoke & heat alarms with a battery back-up supply.
- Grade E – mains only smoke & heat alarms
- Grade F – battery only smoke & heat alarms
This refers to the level of coverage supplied by the system to be installed. Simply put, the number of alarms to fit in the property. The BS 5839: Pt.6 standard lists three ‘Categories’ of system and these are summarised as follows:
- LD1 – alarms fitted in all rooms or areas where a fire may start.
- LD2 – alarms fitted in escape routes and high fire risk areas e.g hall, landing/s plus kitchen and main living room.
- LD3 – alarms fitted in escape routes only e.g hallway and landing/s.
The Building Regulations do not cover existing properties (unless material alterations are taking place e.g an extension). In this type of property BS 5839: Pt.6 should be followed. The minimum requirement for a 2 storey rented property would be Grade D, LD3, but the standard does recommend that a Fire Risk Assessment should be conducted to correctly determine what system should be installed.
5. What is a Fire Risk Assessment?
This is where each individual property is assessed for the fire risk present. The property itself must of course be assessed, as there may be an unusual layout, or other features that could contribute to the consequences of a fire. However, the occupier is often the greatest factor in firstly whether a fire is likely to occur, and secondly what the consequences of the fire are likely to be. The Fire Risk Assessment should be an on-going process that may require amendment at any time. Clearly, this would be very time consuming and create many problems for landlords. To overcome this many landlords are finding that it is easier and possibly cheaper in the long run to install an LD2 category of cover in all properties to minimise the need to undertake a Fire Risk Assessment on every property.
6. If I install an LD2 level of cover can this remove my responsibilities to conduct a Fire Risk Assessment?
The short answer is no! The installation of a Grade D, LD2 system will almost certainly be acceptable for general needs properties, but there may be special needs people or groups that require additional protection e.g alarms for the deaf, and these should be identified. It is likely that specific support groups have this information and may be able to assist.
This will depend entirely upon what their special needs are! Some examples are: the elderly or infirm and the deaf or hearing impaired. The elderly and/or infirm may require additional protection from fire due to the fact that they may be less mobile. Consequently, additional alarms should be considered perhaps in bedrooms. In addition, these groups cannot be expected to climb steps or chairs to test the alarm system. In these instances a Remote System Control switch could be fitted to alleviate this problem. There may also be a need to have a connection to a Warden Call system to alert them to a problem in the dwelling. This can be achieved in most systems by the addition of a relay. The deaf cannot hear a standard smoke alarm, so it may be necessary to add a strobe and vibrating pad to the smoke alarm system.
Choice of Alarm Sensor Type
- The Smoke alarms incorporating either an Ionisation or an Optical sensor are available in mains with Alkaline battery back-up, or mains with rechargeable Lithium back-up formats.
- The Heat Alarms are also available in these ranges, but these only sense heat; not smoke. A comprehensive Fire Alarm system will contain all 3 elements of detection.
- Ionisation Smoke Alarms contain a small sealed ionising source which causes a small electrical current to flow through the air in the smoke chamber. Smoke particles entering the chamber reduce the current, this is sensed by the electronics and when a pre-set threshold level is reached the alarm will sound.
- Optical Smoke Alarms send a pulsed beam of infra red light through the smoke chamber periodically. If visible smoke is present, it scatters the light on to the photodiode light receiver and this is detected by the electronics causing the alarm to sound. Aico Ei Optical Alarms are individually calibrated to ensure correct operation and to reduce the risk of nuisance alarm.
Both have a sufficiently wide range of response to different types of fire to be of general use. However: Ionisation Alarms tend to respond quicker to fast flaming fires producing small smoke particles (e.g flaming wood, petrol). This makes them particularly sensitive to the “invisible” particles produced by toasting, grilling or frying. They are also susceptible to nuisance alarm when redecoration takes place. In view of this, they should be located well away from the sources of such fumes or particles. Optical alarms tend to respond faster to slow smouldering fires producing large smoke particles (e.g smouldering wood, overheating PVC wiring). They are somewhat more susceptible to contamination from dust and fibres so they should not be installed in particularly dusty areas. Both should be removed, or fully covered when renovation work is being carried out.
11. How do Aico Ei Heat Alarms work?
These are fixed temperature alarms which incorporate a thermistor sensor. The thermistor is a heat sensitive resistor,when the ambient temperature reaches a pre-set point of 58°C, the resistance is lowered and the alarm will sound. They are designed for use in areas where due to high levels of dust or fumes, a conventional Smoke Alarm is not suitable. They are particularly suited for use in a kitchen (source of 40% of domestic fires), garages or boiler rooms. Although they are stand alone units they should be interconnected with our Smoke Alarms to provide an adequate warning system in the event of a fire. BS 5839: Pt:6 recommends the use of fixed temperature heat detectors in preference to ‘rate of rise’ types due to the reduced risk of nuisance alarm which can be caused by opening hot oven doors etc.
Both types of Smoke Alarms give good performances in a range of situations. The BS 5839: Pt.6: 2004 British Standards that deals with fire alarm systems in dwellings recommends that the choice of detector should take account of the type of fire that may be expected and the need to avoid false alarms. BS 5839: Pt.6 now strongly recommends the use of optical alarms in circulation spaces of a property, such as hallways and landings and areas in which a likely cause of ignition of furniture or bedding is by a cigarette. Ionisation alarms are considered to be more suited for use in rooms where a fast flaming fire may present a greater danger, dining rooms and bedrooms being possibilities. The standard recommends that in new build properties heat alarms should be installed in kitchens and the ‘Principal habitable room’ e.g. living room; in addition to any smoke alarms used in the escape routes.
They should be sited on the ceiling, close enough to a potential source of fire so they can respond quickly. The Building Regulations requires that the installation of self-contained mains powered with battery back-up Smoke Alarms in all new and refurbished dwelling houses should, at least, meet the following requirements:
- Within 7.5m of any door to a room where a fire is likely to start.
- On each storey of a multi-storey dwelling.
- All Smoke and Heat Alarms in the dwelling should be interconnected.
BS 5839: Pt6 broadly supports these recommendations for alarm systems in existing dwellings, adding that alarms should be sited no more than 3m from bedroom doors so that they can be more easily heard if a fire should occur during the night.We would recommend the fitting of alarms in all rooms (apart from bathrooms and shower rooms) for the earliest possible response. Very large dwelling houses may require more elaborate alarm systems and the relevant sections of BS 5839: Pt6 should be consulted for specific guidance.
One Smoke Alarm in each of the circulation spaces of a property is the minimum recommendation. This would normally mean the hallway, and the landings of any subsequent floors. However, the only way to achieve good coverage is to install an alarm in every habitable room. Building Regulations requires the installation of a heat alarm in the kitchen if there is no door separating it from the circulation spaces. Please note the circulation spaces could be a lounge or dining room in a property where there is no hallway and the stairway leads off a living area.
In summary, they should not be sited in Kitchens, Bathrooms, Shower rooms Garages or other places where there are likely to be excessive nuisance alarms from steam, fumes and high levels of airborne contamination. Heat Alarms are considered more suitable for use in Kitchens and Garages, but not Bathrooms or Shower rooms or places where the normal temperature can exceed 40°C.
The only restrictions to the correct operation of a Smoke Alarm system in a fire situation are: that there are a sufficient number of alarms in the system, sufficient smoke reaches the alarms, they are correctly installed and sited, and that they are regularly maintained and tested for correct operation. If all of these factors are right, there is a very high probability that sufficient warning will be given in life-threatening situations caused by a fire.
Go back to the Frequently Asked Questions index, or read more about the rest of the questions:
17. What cable do I need for the Aico Mains connections and where should the supply be taken from?
18. What cable do I need for the interconnect line?
19. How do I mount the Aico Alarms on the ceiling?
20. Can I fit the Aico Smoke or Heat Alarm on the wall?
21. How many Aico Smoke and Heat Alarms can I link together?
22. Can I use a relay to signal other devices?
23. Can I use the relay to connect to a 24 Volt Fire Alarm System?
24. How often should they be tested?
25. Should they be tested with smoke/heat?
26. What maintenance schedule is recommended?
27. How long will the battery last?
28. How will I know if the battery has failed?
29. How long do Aico Smoke Alarms last?
30. How do I stop nuisance alarms?
31. What is the radiation risk from Aico Ionisation Smoke Alarms?
32. How do I dispose of redundant Aico Ei alarms that contain a NiCad battery?
33. Are the Aico Ei alarms with rechargeable Lithium Cells compatible with previous models?
34. Why choose Aico Ei Professional Smoke Alarms?
To view the available domestic fire alarm systems, visit the Fire and Security section, Fire Alarms, Domestic Fire / Heat Alarms, where you can find an up-to-date selection of Aico smoke alarms, Aico Heat alarms, Aico CO alarms, etc. – buy online Aico fire alarms via SparksDirect.co.uk. This FAQ can also be found online here, here and on the sparksdirect blog..