If you’ve been quoted for an intruder alarm, you’ve probably seen the word “grade” attached to it — Grade 2, Grade 3, sometimes Grade 4. It’s one of the most important decisions in the whole system, and one of the least explained. Here’s what it actually means, in plain English.
What alarm grades are
Intruder alarm grades come from the European standard EN 50131. They describe how much effort and knowledge an intruder would need to defeat the system. The higher the grade, the more sophisticated the attacker the system is built to resist — and the more robust the detection, tamper protection and signalling have to be.
The four grades, briefly
- Grade 1 — low risk. Basic protection for premises where an intruder is expected to have little knowledge and to use simple tools. Rarely sufficient for commercial sites.
- Grade 2 — low to medium risk. Suited to most shops, offices and smaller commercial premises, where an intruder might have some knowledge and use basic tools.
- Grade 3 — medium to high risk. The common standard for higher-value commercial and industrial sites, where an intruder may be experienced, have a good understanding of alarm systems and carry specialist tools.
- Grade 4 — high risk. For the highest-risk sites, where intruders are expected to plan thoroughly and have the resources to do so. Typical of high-value, critical or heavily targeted premises.
Why your insurer cares
This is where grades become more than a technical detail. Many commercial insurers specify a minimum alarm grade as a condition of cover — and if the installed system doesn’t meet it, a claim can be reduced or refused. Before specifying anything, it’s worth checking what your policy actually requires, because the grade you need may be set for you.
How to choose the right grade
The honest answer is that it depends on the site, what you’re protecting, and what your insurer requires — not on a one-size-fits-all rule. Over-specify and you pay for resilience you don’t need; under-specify and you risk both a break-in and a rejected claim. The right grade sits where the genuine risk is.
That’s the assessment we carry out on every intruder alarm system we design: we look at the site, the assets, the way it’s used and any insurance conditions, then specify detection that matches the real risk rather than over- or under-doing it. An alarm is also far more useful as part of one joined-up system — tied in with CCTV so activations can be verified, and access control so the whole site is easier to manage.
If you’re not sure what grade you need — or what your insurer expects — request a site survey and we’ll give you a clear, practical recommendation with no jargon.