EN 50131: intruder alarm grades and classes, explained
EN 50131 is the European standard series for intrusion and hold-up alarm systems. It grades a system by how capable an intruder it has to stop, and classes each device by where it can be mounted. Insurers and specifications quote both, so the design starts there.
Security grades 1 to 4
Each grade assumes a more capable intruder. The grade is chosen from the risk at the site, then every component has to meet it.
| Grade | Risk | The intruder it assumes | Typical use |
|---|---|---|---|
| Grade 1 | Low | Little knowledge of alarm systems and a limited range of easily available tools. | Rarely specified; insurers usually ask for more. |
| Grade 2 | Low to medium | Limited knowledge of alarm systems, a general range of tools and portable instruments such as a multimeter. | Most homes, small shops and offices. |
| Grade 3 | Medium to high | Knows alarm systems well and carries a comprehensive range of tools and portable electronic equipment. | Commercial premises with valuable stock, cash or drugs on site. |
| Grade 4 | High | Plans in detail and has a full range of equipment, including the means to substitute components. | Sites where security comes before every other factor. |
The weakest part sets the grade. The grade of the whole system is the lowest grade of any component in it, so one Grade 2 detector in a Grade 3 design makes the system Grade 2.
From Grade 2 to Grade 3
- Anti-masking. Movement detectors must report when someone covers or sprays them.
- Tamper resistance. Detectors, panels and sirens must withstand and report more ways of being opened or removed.
- Alarm transmission. Signalling to the receiving centre has to meet a higher category, and a failed path must be noticed sooner.
- Every device at Grade 3. Panel, keypads, detectors, sirens, wireless links and power supply all carry the grade.
Environmental classes I to IV
The class says where a device may be installed. A Class II detector belongs indoors; a siren on an outside wall needs Class IV.
| Class | Where | Operating temperature |
|---|---|---|
| Class I | Indoor | +5 to +40 °C |
| Class II | Indoor, general | −10 to +40 °C |
| Class III | Outdoor sheltered, or indoor with extreme conditions | −25 to +50 °C |
| Class IV | Outdoor, general | −25 to +60 °C |
The parts of EN 50131
- EN 50131-1
- System requirements: grades, classes and what the whole system must do
- EN 50131-2-2 to 2-8
- Detectors: PIR, microwave, dual technology, opening contacts, glass break and shock
- EN 50131-3
- Control and indicating equipment (the panel)
- EN 50131-4
- Warning devices (sirens and sounders)
- EN 50131-5-3
- Wireless interconnections
- EN 50131-6
- Power supplies
- EN 50131-7
- Application guidelines for planning and installation
- EN 50131-10
- Supervised premises transceivers for alarm transmission
Designing an EN 50131 system in CCTVplanner
- Alarm panels, detectors and sirens in the catalog show their EN 50131 grade from the datasheet, so a Grade 2 part in a Grade 3 design is visible before it is ordered.
- Detector coverage is drawn on the plan and cut by the walls, the same way camera coverage is.
- The alarm zones calculator sizes the panel and the PIR calculator spaces the detectors.
- Intrusion, cameras and access control share one plan, one cable schedule and one bill of materials. See intrusion detection design.
EN 50131 questions
What is EN 50131?
EN 50131 is the European standard series for intrusion and hold-up alarm systems. Part 1 sets the system requirements, including four security grades and four environmental classes, and the other parts cover detectors, control panels, sirens, wireless links and power supplies.
What grade does a home or a small business need?
Usually Grade 2. Grade 3 is common for commercial premises with valuable stock, cash or drugs on site. The insurer or the specification decides, so check it before choosing equipment.
What is the difference between Grade 2 and Grade 3?
Grade 3 assumes an intruder who knows alarm systems and carries electronic tools. Movement detectors must detect masking, components must resist more tampering, and the requirements for signalling the alarm off site are stricter.
What grade is a system with mixed components?
The grade of the system is the lowest grade of any component in it. One Grade 2 detector in a Grade 3 design makes the whole system Grade 2.
What is BS EN 50131?
The British adoption of the same European standard. In the UK it is applied through PD 6662, which police response policy and most insurers refer to.
Summary of EN 50131-1 and the EN 50131 series published by CENELEC.