Intrusion alarm grades, marked from Grade 1 to Grade 4, describe how resistant an intrusion and hold-up alarm system is to attempts to defeat it. Understanding these grades is crucial during design, because they determine the choice of control panels, detectors and sounders, as well as compliance with insurer requirements. The classification comes from the EN 50131 standard, which organises the whole field of alarm systems in Europe and is the basis of the Polish PN-EN 50131 series.
The EN 50131 standard and where the grades come from
EN 50131 is a set of standards defining requirements for intrusion and hold-up alarm systems. It specifies parameters for control panels, detectors, transmission devices, power supplies and sounders. The four resistance grades are tied to the offender profile: the higher the grade, the more advanced the intruder the system must stop, and the harder it is to mask or bypass. The standard also describes functional requirements, such as tamper supervision, the way faults are signalled and the minimum power hold-up time.
Grade 1 to Grade 4 - characteristics
- Grade 1 - low risk. Assumes an opportunistic offender with little knowledge, using commonly available tools. Rarely used, mainly in facilities with negligible protected asset value.
- Grade 2 - low to medium risk. The offender has basic knowledge of alarm systems and simple tools. This is the typical level for flats, small shops and offices.
- Grade 3 - medium to high risk. The offender knows alarm systems, has electronic tools and can use them. Required in higher-value facilities: banks, jewellers, pharmacies, industrial sites.
- Grade 4 - high risk. Assumes an organised offender with full knowledge and advanced equipment, ready for a planned operation. Used in strategic, military and critical infrastructure facilities.
When a given grade is required
In practice the system grade is set by a risk assessment and by the requirements of an external party, most often the insurer. An insurance policy for a high-value facility often explicitly imposes a minimum grade and certification of the installed devices. For facilities subject to regulations on the protection of persons and property, the grade follows from ordinances and security plans. Before selecting equipment, agree the required grade with the investor and insurer, because installing lower-grade panels may lead to a refusal to pay compensation. In many cases it ends at Grade 2 for standard facilities and Grade 3 where asset value or regulations raise the requirements.
System components versus grade
Grade does not apply to a single device but to the whole system. Every component must meet the requirements of a given class:
- An alarm control panel with appropriate certification and number of areas.
- Detectors with tamper and masking detection - anti-masking detectors are required for higher grades.
- Sounders with backup power and tamper protection.
- Backup power with a hold-up time dependent on the grade.
- Alarm transmission to a monitoring station with line integrity supervision.
ICT access control systems integrate with intrusion modules, so a single platform manages area arming and alarm response. You will find devices in the Access control and intrusion category, while advanced automation scenarios are handled by the Protege GX platform.
Alarm transmission and event verification
As the grade rises, so do the requirements for the alarm transmission system to the monitoring station. The standard defines classes of transmission systems that account for signal delivery time and line integrity supervision. For higher grades a single transmission path is not enough: a primary and a backup path are used, for example an IP network with a cellular path as backup. Increasingly, event verification is also required, meaning confirmation of an alarm by a second independent factor, such as a camera image, to reduce the number of false interventions.
Environmental classes - a frequently overlooked parameter
Besides the resistance grade, EN 50131 also defines environmental classes (I to IV), which describe the operating conditions of a device: temperature, humidity, resistance to interference. A detector intended for indoor use (class I) will not perform outdoors. When selecting components, check both classes at once, because the reliability of the system throughout the year depends on it. Selecting outdoor devices with too low an environmental class is one of the more common causes of false alarms in winter and during precipitation.
Need help selecting a system grade for a specific facility? Write to us - we will analyse the requirements and select certified devices for the right grade.