The purpose of the EN 50131 standard is to define the requirements for alarm systems in general, as well as for each individual component, stating the required system performance specifications.
In 1986 in Great Britain, the British Standards Institution issued guidelines on the grading of security systems in relation to the level of security they provide. These guidelines were known as BS 4737. On 4 April 2006 the technical committee for security systems known as CENELEC TC79 drew up and issued updated guidelines, which were established as a European specification under the name EN 50131 and replaced the old British standard.
The EN 50131 standard consists of 9 parts, which are set out as follows:
EN 50131-1: General requirements for intruder and hold-up alarm systems.
EN 50131-2: Intruder detectors.
EN 50131-3: Control and indicating equipment (keypads).
EN 50131-4: Warning devices (sirens).
EN 50131-5: Interconnections (communication between detectors and the control panel).
EN 50131-6: Power supplies.
EN 50131-7: Application guidelines – installation.
EN 50131-8: Smoke systems.
EN 50131-9: Verification of genuine alarms.
The purpose of the EN 50131 standard is to define the requirements for security systems installed in buildings, using wired or wireless interconnections. These requirements also apply to the components of the security system that are usually installed outside the building (e.g. warning devices). This standard refers to the performance specifications of security systems and does not prescribe methods of design, installation, operation or maintenance.
Differences between BS 4737 and EN 50131
There are four notable differences between the old British standard and the new European standard, which make the European standard superior to the British one.
The European standard adopts the principle of grading the security level of the security system, in terms of both the security provided and its scope for expansion. It introduces 4 security levels, which are analysed below.
The performance and durability of each component must be subject to a security level. Each component will state which security level it is compatible with.
The new standard provides security system installers with application guidelines for each protection level separately. These guidelines are based on the possible points of access that each site has, which must be examined when the site survey is carried out. In addition, installers must carry out and document a risk assessment before designing the system.
Maintenance of the alarm system is more flexible under the new standard, since for levels 2 and 3, one of the two maintenance visits per year can be carried out remotely.
Risk analysis
Risk analysis is the process needed to determine the security level of an alarm system and is essential for its design. In a risk analysis, the designer and the user are asked to record certain details of the protected site, such as:
-Contents of the site
-Type – Easy to remove, attractive for burglary, attractive for robbery.
-Value.
-Size.
-History – Methods used in a previous burglary or robbery.
-Hazard – Dangerous to the environment or to people.
-Destruction – Risk of arson.
-Building infrastructure
-Construction of the building – Material of walls, floor, roof.
-Openings – Number of doors, windows, skylights.
-Use of the building – Whether it remains closed for long periods, or is open to the general public.
-Key holders – How many people have access.
-Location – Urban centres, countryside.
-Area – High or low crime rate in the area.
-Existing security infrastructure – railings, guards.
-History.
Local regulations or legislation – Fire safety regulations that affect the design of an alarm system.
The risk analysis approach should lead to a higher level of security that is proportionate to the requirements of the protected site.
Security grades
The EN 50131 standard rates security systems in 4 grades, according to the skill, means and determination that criminals may exercise at each level. This grading is based on the functional specifications of the components, without compromising the required performance and their resistance to the expected severity of attack. They concern the design of all the components of the security system, such as the control panel, detectors, interconnections, control devices, power supplies and signalling components. The final grading of the entire system cannot be higher than that of the component with the lowest security grade!
The four security grades under the EN 50131 standard are as follows:
Grade 1: Low security level. At this level the system is required to protect the site from burglars who have no knowledge of security systems. In addition, for the break-in they use basic tools of limited use.
Grade 2: Low to medium security level. At this level the system is required to protect the site from burglars who have basic knowledge of security systems. In addition, for the break-in they use general, widely available tools, as well as basic portable measuring instruments (e.g. a multimeter).
Grade 3: Medium to high security level. At this level the system is required to protect the site from burglars who are familiar with security systems. In addition, for the break-in they use a comprehensive range of tools, as well as portable electronic equipment (e.g. a laptop).
Grade 4: High security level. At this level security takes precedence over all other factors, and the burglars are assumed to have the knowledge and means to put together a complete break-in plan. They also carry equipment suitable even for replacing components of the security system.
Table 1 shows some of the requirements for the system to be rated at one of the 4 security grades:
System autonomy
Power supply systems must also fall within one of the 4 security grades, as well as one of the 4 environmental classes (section 7.6). There are three types, which describe the type of power supply and are based on the method of providing an alternative power source:
Type A: Requires a main power source (e.g. mains electricity supply) and an alternative power source that is recharged through the alarm system, for example a rechargeable battery connected to the alarm system.
Type B: Requires a main power source and an alternative power source that is not recharged through the alarm system, for example a rechargeable battery connected to an independent charger.
Type C: Requires a main power source and an alternative power source in the form of a battery of limited capacity.
Power supplies must be capable of supporting the alarm system in all conditions, even for the time needed to charge the batteries, as described in a following table. It is important to note that switching from the main to the alternative power source, and vice versa, must not create conditions that trigger the alarm system. Depending on the security grade of the system, and on the type of power supply, the table below shows the minimum time for which the power supply must support the system in full operation in the event of a main power failure.
Charging time means the time needed for the battery of a type A power supply to charge to 80% of its capacity.
Depending on the security grade, in addition to the requirement to connect the alarm system to the 24-hour alarm receiving centre, there is also a requirement concerning the maximum interval at which this communication is checked. The table below shows the communication times in relation to the security grade.
Environmental class
In addition to the security grade, the components of the alarm system must be classified in an environmental class. Depending on the class to which a system component belongs, it must operate correctly when exposed to these environmental conditions.
Environmental class I: Indoor
This refers to the environmental conditions that prevail when the temperature of the space is closely controlled (e.g. the rooms of a house). The temperature of the space may vary between +5°C and +40°C.
Environmental class II: General indoor space This refers to the environmental conditions that prevail when the temperature of the space is not as closely controlled (e.g. a stairwell). The temperature of the space may vary between -10°C and +40°C.
Environmental class III: Covered outdoor space or indoor space with extreme conditions
This refers to the environmental conditions that prevail in an outdoor space that is nevertheless sheltered from the weather (e.g. a shed). The temperature of the space may vary between -25°C and +50°C, with humidity of 75% without condensation. For 30 days a year the average humidity may vary between 85% and 95% without condensation.
Environmental class IV: Outdoor space
This refers to the environmental conditions that prevail in an outdoor space that is exposed to the weather (e.g. open country). The temperature of the space may vary between -25°C and +60°C, with humidity of 75% without condensation. For 30 days a year the average humidity may vary between 85% and 95% without condensation.
Access levels & Use of the system
Certain functions of the alarm system, depending on its security grade, must be permitted or prohibited for certain users. The rights of each user of the alarm system are defined by the access levels:
Level 1: Access by anyone.
Level 2: User access.
Level 3: Installer access.
Level 4: Manufacturer access.
Access to level 3 and 4 functions will be permitted only if approval has been given by the level 2 user, while for level 4 approval must previously have been given by the level 3 user.
In addition to the functions that are or are not permitted depending on the user’s access level, the EN 50131 standard also specifies under what conditions activation of the alarm system is permitted.
Maintenance
Depending on the security grade, certain maintenance tasks must be carried out on the system, both locally and remotely, so that the system is maintained at the security level for which it was designed. Maintenance carried out locally must include:
-Checking the arming – disarming procedure.
-Checking the entry and exit procedure for the protected site.
-Any wear or damage to the interconnections.
-The power supplies and the battery.
-The operation of the detectors, magnetic contacts, panic buttons, etc.
-The operation of the warning devices.
-Communication with the 24-hour receiving centre.
-Particular attention must be paid to returning the system to its original state after each check. As regards maintenance carried out remotely:
-The end user must be informed and have agreed in writing.
-Remote access must be recorded in the panel’s event log.
-It must be limited in duration.
-It must not create conditions that trigger the alarm.
-Problems identified during the remote maintenance procedure must be reported to the end user, and the corrective actions must be immediate.