Grade 2 vs Grade 3 Alarms Explained: PD 6662, Insurers and Ajax
An intruder alarm's grade, from 1 to 4 under BS EN 50131-1, tells you how skilled and well-equipped a burglar it is built to hold off. Grade 2 is the usual level for homes and lower-risk businesses. Grade 3 is what insurers typically look for on high-risk homes and most commercial premises. The whole system takes the grade of its lowest-graded part. Ajax's graded Baseline Jeweller devices are Grade 2, and its Superior G3 range reaches Grade 3.
Our Ajax wireless alarms page lists each device's grade; this guide explains what the grades mean and what each costs in Ajax parts.
What does an alarm grade actually tell you?
Grades come from BS EN 50131-1, the British edition of the European standard for intrusion and hold-up alarm systems (BSI lists BS EN 50131-1:2006+A3:2020 as current). Each grade assumes a different kind of intruder, and the equipment has to resist more as the grade rises.
| Grade | Intruder assumed (BS EN 50131-1) | Where insurers typically expect it (BIBA) |
|---|---|---|
| 1 | Little alarm knowledge, a few easily found tools | Generally disregarded |
| 2 | Some alarm knowledge, general tools and portable instruments such as a multimeter | Higher-risk homes and lower-risk commercial premises; unmonitored systems for lower-risk homes |
| 3 | Familiar with alarms, a full tool kit and portable electronic equipment | High-risk homes and most commercial premises |
| 4 | Plans in detail, with full equipment including means to swap components | Very rarely asked for |
One key difference is masking. At Grade 3, movement detectors must report being covered or sprayed when the system is set. BIBA's guidance, written with the insurers' body RISCAuthority, says this matters most where the public can reach detectors unnoticed, such as shops.
Why does one weak device decide the grade?
BS EN 50131-1 grades every component, and a system can only claim the lowest grade among its parts. One lower-graded door contact in a Grade 3 installation pulls the whole system down to the contact's grade, however well the rest is rated. Power supplies and range extenders count too.
Ajax makes this easy to check: most of its specification pages list the device's Security Grade, environmental class and certifying test house.
Where does PD 6662 come in?
PD 6662 is the BSI scheme that applies the European alarm standards in the UK. BSI lists PD 6662:2017 as the current release, and the NSI says it took effect on 1 June 2019. It ties together the BS EN 50131 product standards, the system rules in BS EN 50131-1 and BS 8243, which covers designing systems to produce confirmed alarms.
What do insurers and the police ask for?
Insurers set their own conditions, so your policy schedule is what counts. BIBA says grades 2 and 3 are the ones most often required, and that inspectorate-listed alarm companies must carry out a formal risk assessment, which helps set the grade.
A police response needs a Unique Reference Number (URN). The NSI says a URN can be awarded to systems certificated to PD 6662 and BS 8243 that its approved companies install, maintain and monitor. SSAIB says only installations with its Certificate of Compliance qualify. BIBA lists what a URN needs:
- a PD 6662 system at Grade 2, 3 or 4
- monitoring by an NSI or SSAIB listed alarm receiving centre
- confirmed activations, as the police only attend a confirmed intruder alarm
- at least two keyholders who can reach the premises within 20 minutes
These rules sit within the National Police Chiefs' Council (NPCC) policy on response to security systems, covering England, Wales and Northern Ireland, which the NSI reports was updated in 2025. In Scotland, ask the installer about Police Scotland's requirements.
Which Ajax devices are Grade 2 and which are Grade 3?
Ajax splits its intruder range into Baseline and Superior. Graded Baseline Jeweller devices are Grade 2. Many Superior devices share that grade; those with G3 in the name, the Superior Hub Hybrid and MegaHub panels and most wired Fibra devices are Grade 3. So check the name and specification, not just the word "Superior".
| Part | Baseline (Grade 2) | Superior G3 (Grade 3) |
|---|---|---|
| Hub | Hub 2 (2G) Jeweller, £161.53: 100 devices, 50 users, up to 15 hours on battery | Superior Hub G3 Jeweller, £391.85: 250 devices, 200 users |
| Motion detector | MotionProtect U Jeweller, £58.84 | Superior MotionProtect G3 Jeweller, £77.69, with anti-masking |
| Door contact | DoorProtect U Jeweller, £50.76 | Superior DoorProtect G3 Jeweller, £81.12, detects a second magnet used to fool it |
| Keypad | KeyPad Plus Jeweller, £116.54 | Superior KeyPad Plus G3 Jeweller, £133.66 |
| External siren | StreetSiren Jeweller, £119.99 | Superior StreetSiren Plus G3 Jeweller, £190.78 |
Prices include VAT, delivery is extra, and prices can change. Grades and figures are from Ajax's specification pages.
How is an Ajax system set up for PD 6662?
Ajax says a system can be configured to PD 6662:2017 on hubs running OS Malevich 2.10 or later, in its PRO apps (Ajax PRO and Ajax PRO Desktop), so it is an installer's job. The key settings are:
- Alarm confirmation zones, so a confirmed intrusion needs more than one detection
- Hold-up confirmation: a short and a long press on a DoubleButton, or two chosen DoubleButtons pressed within a timer of 8 to 20 hours
- Restoration after alarm, so the system cannot be set again until an authorised user or installer resets it
DoubleButton Jeweller (from £49.77) lists PD 6662:2017 among its standards, and Superior DoubleButton G3 Jeweller (£55.97) is the G3 version. The Holder that fixes either button to a surface is in our Ajax accessories and brackets.
Can a wireless alarm reach Grade 3 now?
In 2017 Ajax wrote that no wireless Grade 3 system was on the market. On 2 March 2026 Ajax announced a fully wireless range certified to EN 50131 Grade 3, built around Superior Hub G3 Jeweller. Ajax says its radio switches between 17 frequencies across four bands to resist jamming, and that the hub's two internal battery options, rated up to 16 and 60 hours, meet the grade's requirements.
The weakest-link rule applies again: Ajax says enhanced frequency hopping only works when every device on the hub uses Superior Jeweller, so use G3 devices throughout. For a wired site, Superior Hub Hybrid 2 (£410.12) is also Grade 3 and runs Fibra wired devices alongside wireless ones.
Our take
For most homes and lower-risk small businesses, a well-planned Grade 2 Ajax system does the job for noticeably less. Step up when your insurer asks, when cash or stock is within reach of the public, or when the site is high value. Ask your insurer which grade they want before you buy, then keep every device at that grade or above.
We supply Ajax equipment; we don't fit it. Depending on the job and area, we can recommend a qualified installer. For police response, that must be an NSI or SSAIB approved company.
Not sure which grade your policy means? Call us on 01902 902251, send us your policy wording and floor plan, or browse the full Ajax range. We ship nationally to England, Scotland and Wales.
Alarm grades: quick questions
Is Grade 2 enough for a house?
Usually. BIBA says insurers typically see it as suitable for higher-risk homes, with an unmonitored system enough for lower-risk ones. Your policy wording decides.
Do I need Grade 3 for a police response?
No. A PD 6662 system at Grade 2 or above can get a URN, if approved companies install, maintain and monitor it and it produces confirmed alarms.
Can I mix Baseline and G3 Ajax devices?
They can share a hub, but the system then takes the lower grade.
Can I fit a graded Ajax system myself?
A self-monitored home system with no insurance condition can be set up in the Ajax app. Police response needs an NSI or SSAIB approved company to design, fit and maintain it; if your insurer names a grade, check its installer wording. Ajax says only its accredited partners may install and maintain Superior devices.
Source: Ajax Systems blog on security grades, Ajax's wireless G3 announcement, PD 6662 set-up guide and Superior Hub G3 page. UK sources: BSI (BS EN 50131-1), BSI (PD 6662), NSI on PD 6662:2017, URNs and the 2025 NPCC policy, SSAIB, and BIBA with RISCAuthority.
