Physical Security
Intrusion alarm systems: EN 50131 security grades 1 to 4 explained
Grade 2 or grade 3? EN 50131 defines how resilient an intrusion alarm system must be. Here is how to find the right grade, the right detectors and a sensible transmission path.
Q-entra editorial teamPublished on 6 min read
Contents
- What EN 50131 covers and why the grade matters
- The four security grades at a glance
- Environmental classes: detectors for the right location
- Detector types: PIR, dual technology, glass break, magnetic contacts
- Setting and unsetting: arming in everyday use
- Alarm transmission under EN 50136: where does the alarm go?
- Avoiding false alarms and involving your insurer early
- Maintenance and next steps
Key takeaways
- EN 50131 divides intrusion alarm systems into four security grades, based on the risk and the expected skill of an intruder.
- Homes and many smaller offices are usually grade 2, businesses with higher values grade 3, and grade 4 is reserved for high-security areas.
- A system is only as strong as its weakest component: detectors, control panel and transmission must all match the chosen grade.
- Whether alarms go to you or to an alarm receiving centre of your choice determines the response in an emergency.
- Clarify insurer requirements in writing before planning, and have the system maintained at least once a year.
What EN 50131 covers and why the grade matters
The EN 50131 series sets out the requirements for intrusion and hold-up alarm systems in Europe. At its heart are four security grades: the higher the risk and the more skilled the expected intruder, the higher the grade. Grade 2 is usually enough for homes and many smaller offices, businesses with higher values often need grade 3, and grade 4 is intended for high-security areas.
The grade determines how well detectors and the control panel are protected against tampering, how long the backup power must last and how reliable the transmission path has to be. As a rule, the system is only as strong as its weakest component. A grade 3 control panel combined with grade 2 detectors results in a grade 2 system for the area concerned.
The four security grades at a glance
| Grade | Risk | Expected intruder | Examples |
|---|---|---|---|
| 1 | Low | Little knowledge of alarm systems, simple and readily available tools | Rare in commercial practice |
| 2 | Low to medium | Limited knowledge, common tools and simple measuring instruments | Flats, houses, small offices and practices |
| 3 | Medium to high | Familiar with alarm systems, a comprehensive set of tools and portable electronics | Shops and warehouses with valuable goods, businesses with high values |
| 4 | High | Plans in detail, has full equipment up to replacing system components | High-security areas such as vaults |
The examples are a guide, not a rule. The right grade follows from a risk assessment: what values are kept on site, how exposed is the site, and how long until someone responds? Insurers often specify a minimum grade as well.
Environmental classes: detectors for the right location
Alongside the grade, four environmental classes describe the conditions a component must withstand, such as temperature and humidity. Class I covers heated indoor rooms, class II indoor areas with fluctuating conditions such as stairwells or unheated storerooms, class III sheltered outdoor locations and class IV exposed outdoor locations. A class I indoor detector therefore has no place under a canopy or in an unheated garage.
Detector types: PIR, dual technology, glass break, magnetic contacts
Motion detectors: PIR and dual technology
Passive infrared (PIR) detectors recognise the heat radiation of a body moving through the room. They are proven and affordable, but if poorly positioned they react to radiators, direct sunlight or warm air currents. Dual technology detectors combine PIR with microwave and only trigger when both detect something, which reduces false alarms in difficult rooms. From grade 3 upwards, motion detectors must also detect when they are covered or sprayed (anti-masking).
Glass break detectors
Acoustic glass break detectors analyse the characteristic sound of breaking glass and report a break-in before anyone is inside the room. How well they work depends on the room: heavy curtains, laminated glass or window films can affect detection. Check the manufacturer's specifications for glass type and distance.
Magnetic contacts and bolt contacts
Magnetic contacts on doors and windows report when they are opened. Bolt contacts in the strike plate also show whether a door is actually locked. Higher grades use contacts that cannot easily be fooled with an external magnet.
Setting and unsetting: arming in everyday use
An alarm system only protects if it is armed reliably. Operation should fit your daily routines. These concepts have proven useful:
- Full set: all detectors are active and nobody is in the building. An alarm is reported externally.
- Part set: only the building shell is active, for example at night in a home or during late shifts. People can move freely inside.
- Areas: separate areas such as the shop floor, office and warehouse are armed independently, for example when there are several tenants.
- Enforced arming logic: the system can only be set when all monitored doors and windows are closed, and an armed area cannot be entered without unsetting it first. Known in German-speaking countries as Zwangsläufigkeit, this established principle prevents many operating errors.
- Operation: by keypad with a personal code, key fob, app or access control. Entry delays should be as short as is practical.
Alarm transmission under EN 50136: where does the alarm go?
A siren deters but triggers no response on its own. What matters is who receives the alarm. The EN 50136 series covers alarm transmission systems and divides them into categories for a single path (SP1 to SP6) and for two independent paths (DP1 to DP4). Higher categories set stricter requirements, including how quickly the failure of a transmission path is detected. The category you need depends on the grade and your insurer's requirements.
There are two basic options. You are notified by app, call or text message and respond yourself. Or the system transmits to the alarm receiving centre of a security company you choose; it is staffed around the clock and follows an agreed response plan, such as calling back, sending a patrol or notifying the police.
If you use an alarm receiving centre, look for one certified to EN 50518. A push notification is convenient, but nobody guarantees it will be read at night. In practice, transmitting over the internet and the mobile network in parallel works well.
Modern control panels are networked, so they belong in their own network segment without port forwarding. Our article on the convergence of physical and cyber security explains why security technology and IT security belong together.
Avoiding false alarms and involving your insurer early
False alarms are stressful, may lead to call-out charges and, above all, erode trust: responders called out for nothing too often take the next alarm less seriously. Typical causes are operating errors, poorly positioned detectors and poor maintenance. These measures help:
- Choose detectors to suit the room and do not point them at radiators, windows or vents.
- Brief all users and give each person their own code or key fob.
- Use enforced arming logic and short but practical delay times.
- Verify alarms, for example by confirmation from a second detector or through video verification.
- Replace wireless detector batteries and the panel's backup battery in good time.
Clarify your insurer's requirements before planning starts and get them in writing: the required grade, certification of components and installer, transmission path and category, connection to an alarm receiving centre and maintenance intervals. Checking this only after installation risks costly retrofits or, after a loss, disputes about cover.
Maintenance and next steps
An alarm system is not something you install and forget. At least once a year, and more often depending on grade and insurer, detectors should be walk-tested, sirens and batteries checked, the transmission to the receiving centre tested and the firmware updated. Just as important: delete former employees' codes and key fobs, and update the design when the building changes.
If you are planning a new system or want an existing one reviewed, Q-entra supports you with alarm systems to EN 50131, from risk assessment and installation to coordination with your chosen alarm receiving centre.
