Intruder alarm grades are a crucial consideration for all UK businesses that are serious about security. The grade of alarm system your business requires will depend on the risk level of your property. Choosing the right grade is vital for safeguarding staff and assets. It’s also likely to be something you must comply with, in order to satisfy the requirements of your insurance policy. In this guide, we’ll explain the EN50131 standard, what it is, what systems are included and what this means for your business.
The grading of security alarms fitted at UK business premises is outlined in the EN50131 European standards for intruder alarm systems. This set of guidelines also became known as BS EN50131, after it was adopted by the British Standards Institution. Through their PD6662 scheme, the BSI introduced these European guidelines to boost intruder alarm standards across the UK.
EN50131 was originally adopted back in 2005 but, after various revisions, it remains a crucial reference point for British businesses now and beyond. Crucially, the EN50131 standard now works in conjunction with BS 8243:2021 (formerly DD 243) to define the specific steps an Alarm Receiving Centre (ARC) must take to confirm an alarm is genuine before police are called. This process, known as Sequential Confirmation, is essential for meeting the latest police requirements and maintaining a Level 1 police response.
Understanding EN50131 and the subsequent security grade is inextricably linked to securing a Police Unique Reference Number (URN) for your system. The National Police Chiefs’ Council (NPCC) dictates that police in the UK will only respond to intruder alarms that are confirmed as genuine and are installed, maintained, and monitored by an approved company, such as an NSI Gold accredited provider, and possess a valid URN.
This is a critical factor for business security, as a system that does not comply with the required grade and verification process (BS 8243) will likely be classed as an unmonitored alarm for police purposes. The NPCC’s Requirements and Response to Security Systems policy outlines a strict “three-strikes” rule: if the police attend three unconfirmed false alarms within a 12-month rolling period, your URN can be temporarily withdrawn, meaning a response will cease until the system is brought back into full compliance. Therefore, choosing the correct grade and partnering with a reputable installer is a fundamental part of a robust security strategy.
All intruder alarm systems are included in the EN50131 guidelines, along with hold-up alarms (together they are referred to as I&HAS). Intruder alarms detect when somebody has broken into your property. Hold up alarm systems allow employees at a workplace to silently trigger a police response in the event of an attack on-site. They are otherwise known as duress alarms or panic alarms.
Modern commercial security systems go beyond just detecting breaches. They often integrate with CCTV monitoring services and access control systems. The EN50131 standard focuses specifically on the Intruder and Hold-Up Alarm System (I&HAS) itself, but the overall effectiveness relies on integrating these components into a cohesive solution. For example, a Grade 3 system often uses detector-activated CCTV (meeting BS 8418 standards) to provide the visual confirmation needed by an ARC to verify an alarm before contacting the police, which is essential under the latest protocols. This holistic approach is key to effective site protection.
The key element of the EN50131 standard is the system of grades it outlines. These classify the level of sophistication that is required for the alarm system installed. The higher the risk of crime to your property, the more sophisticated the system you will require and the higher the grade. There are four intruder alarm grades, which include:
Premises that require a grade 1 security system are unlikely to be targeted by criminals. The biggest security risk is from opportunistic thieves with little knowledge of alarm systems.
This type of intruder alarm system is most commonly installed at domestic properties, where the inclusion of an alarm is not required for insurance purposes. It guards against intruders who are most likely to break in and enter through a front or back door.
An EN50131 grade 2 alarm system is required for buildings that house valuable property. This could result in a higher risk of theft as the property may attract the attention of more experienced criminals.
Potential intruders may be more savvy thieves who carry tools, have knowledge of intruder alarms and consider accessing the building through windows, as well as doors. A grade 2 wireless alarm system or hard wired alternative is therefore required to defend against this.
Examples of a property where a grade 2 alarm would typically be appropriate is a low-risk commercial property with a cash register such as a bakery, florists or hairdressers. This grade is typical for many small businesses and those in the food sector that do not store substantial cash or high-value items overnight. Grade 2 systems must feature tamper protection on the main panel and detectors, and offer a minimum 12-hour battery back-up, ensuring continued protection even if the mains power is cut.
Alarms that fall under this security grade of the EN50131 need to protect against a more substantial threat of theft. The property in question contains high-value contents and this is expected to catch the attention of a more seasoned criminal. These types of thieves have experience in tampering with intruder alarm systems and carry tools and equipment to overcome them.
An EN50131 grade 3 alarm system is sophisticated enough to protect against this higher threat of crime and is usually installed at most commercial premises such as a newsagent or a department store. Grade 3 is the most common requirement for premises needing an insurer-approved, police-monitored system, including those in the retail sector, most office buildings, and premises dealing with sensitive or high-value goods. The system must include superior tamper protection on all wiring and components, and the detection devices must be more robust, often requiring dual-technology sensors to prevent false alarms. Alarm communication must use two separate paths, such as a phone line and a secure GSM network, to ensure the signal always reaches the Alarm Receiving Centre (ARC).
The rising prevalence of commercial crime, with the Office for National Statistics (ONS) reporting a 20% rise in shoplifting offences in the year ending March 2025, underscores the need for Grade 3 protection in many business environments.
Grade 4 alarm systems are the most sophisticated available. They are required to protect extremely high-risk commercial properties, which house highly valuable contents. An example of a relevant property would be a bank, art gallery, high-end jewellers or office that deals with classified information. This level of security is also often mandated for government facilities, high-security data centres, and specialised parts of the healthcare sector dealing with controlled substances.
These kinds of properties could warrant the attention of a well-organised thief, who may not be working alone. These types of criminals may well have the knowledge and equipment required to prevent detection. They may consider all possibilities when it comes to breaking and entering the property, including access via the ceiling or floor. Grade 4 demands the highest level of system resilience, requiring a 24-hour battery back-up and the use of components certified to the most rigorous standards to counter even the most sophisticated attack plans. This is about providing the ultimate security against professional, organised crime gangs.
While EN50131 focuses on the physical security of your premises, it’s important to acknowledge the modern convergence of threats. Intruders may attempt to compromise your physical security system remotely via your network, or a successful physical break-in could be a means to access critical IT infrastructure. The UK Government’s Cyber Security Breaches Survey 2025 revealed that 43% of UK businesses reported a cyber attack or breach in the last 12 months, with sophisticated phishing and ransomware attacks on the rise. This highlights the need for an integrated approach where physical security, like a Grade 3 or 4 alarm, is complemented by robust IT and smart security measures.
When reviewing your security needs, consider the integrity of your network alongside the physical integrity of your building. A security provider that understands both the EN50131 standard and the requirements of network protection, such as those discussed in our article on how to build a security-first culture, is essential for a comprehensive defence.
If you’re unsure as to the grade of alarm your business requires, the first step is to have a risk assessment carried out on your property. This is another key recommendation within the EN50131 guidelines. It will highlight all risk factors to establish the most suitable grade of system required. A qualified security surveyor will use the British Standard PD6662:2017 (which incorporates EN50131 and BS 8243) to formally determine the necessary grade based on the premises’ contents, location, construction, and existing security measures.
Each and every component within an intruder alarm system is graded. So it’s important to note that the overall grading is equal to the lowest graded component.
For example, if you have a grade 2 certified detection sensor and a grade 3 certified alarm transmission system, then the system as a whole is rated at just grade 2. This rule means that a system is only as strong as its weakest link, emphasising the need for professional intruder alarm installation by an NSI or SSAIB certified company.
Beyond the installation grade, the quality of your monitoring is vital. Alarm monitoring centres must operate to the BS EN 50518 standard (superseding BS 5979), ensuring maximum reliability and security for receiving and acting on your alarm signals. The NPCC policy makes it clear that only professionally monitored alarms with a URN will receive a police response, making the choice of security system certification crucial for both compliance and effective protection.
Our friendly team of security experts are on hand to provide advice to you and your business. Just get in contact if you have any questions. You may also be interested to read our article on what your employees should know about intruder response procedures or download the BS EN 50131-1 document from the British Standards Institution.
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