Four sensors in one. The smartest entry contact.
A wireless door and window sensor that combines opening detection, shock detection, tilt detection, and magnetic-masking protection in a single compact device. Detects forced entry, sustained vibration, door-tilt, and magnetic interference — replacing what would normally need three separate devices.
Free site survey · Fixed-price quote · Same-week installation across London. No-obligation, no high-pressure sales — just a certified Ajax engineer assessing your property and recommending the right system.
Takes 60 seconds. No obligation.
Traditional door contacts only detect opening. DoorProtect G3 detects four different intrusion methods — including sophisticated tampering attempts that would defeat standard sensors. One device, comprehensive protection.
Magnetic reed switch detects the exact moment a door or window is opened. Standard reliable functionality, the foundation of any intruder alarm.
Built-in accelerometer detects sustained vibration from forced-entry attempts: kicks, prying, drilling. Sensitivity adjustable per installation.
Detects when a door is being tilted off its hinges or a window forced from a closed-but-not-opened state. Catches bypass methods other sensors miss.
Detects attempts to defeat the contact by holding a strong magnet near it (a known burglar tactic). Generates a tamper alert immediately.
Lithium battery powers all four functions for up to 7 years. Battery health reported to the Hub — you'll know months before replacement is needed.
Wired input terminal lets you connect a third-party detector (panic button, glass break, smoke) into the Ajax system through DoorProtect G3.
DoorProtect G3 is the standard entry-point sensor for most Ajax installations. We typically fit one on every external door and window plus key internal doors that protect valuables.
Primary protection at every exterior door. Detects opening, vibration from kicks, and tilt from forced bypass attempts.
Casement, sash, and sliding windows. Compact size suits all window types. Discrete white or black finish.
Internal protection for high-value rooms. Restrict access during specific hours, alert on out-of-hours opening.
1.6km wireless range reaches outbuildings. Weatherproof variants available for exposed locations.
Complete technical specifications. Specs may be updated by Ajax through firmware revisions — confirm latest at site survey.
| Detection | |
|---|---|
| Sensors | Magnetic reed + accelerometer + tilt sensor + magnetic-masking detector |
| Detection types | Opening, shock, tilt, magnetic masking |
| Magnet detection range | Up to 100mm contact gap |
| Tamper protection | Wall-removal and case-open switches |
| Communication | |
| Wireless protocol | Jeweller (encrypted, frequency-hopping) |
| Range to Hub | Up to 1,600m line of sight |
| Encryption | AES with floating key |
| Signal interval | Configurable, typical 36s |
| Power | |
| Battery type | 1× CR123A lithium (included) |
| Battery life | Up to 7 years (typical use) |
| Low-battery alert | Reported to Hub well in advance of failure |
| Environment & Compliance | |
| Operating temperature | -10°C to +40°C indoor / -25°C to +50°C outdoor variants |
| Humidity | Up to 75% |
| Security grade | EN 50131 Grade 3 |
| UK compliance | PD 6662:2017 |
| Physical | |
| Dimensions | 100 × 25 × 15 mm (sensor body) |
| Magnet body | Smaller paired magnet |
| Colour options | White, Black, Brown (and outdoor variants) |
| Mounting | Adhesive or screw fix |
Indicative installed pricing based on typical UK market conditions. Final price confirmed at survey.
Per-unit installed price. Most homes use 4-8 DoorProtect G3 sensors. Volume pricing applies on larger installations. Final cost confirmed at survey based on quantity and mounting.
Get Exact QuoteDoorProtect G3 is the latest generation, adding magnetic-masking detection (older versions don't have this). G3 is what we recommend for new installations. The older DoorProtect Plus is still functional and supported but lacks the magnetic-masking protection.
Yes — DoorProtect G3 is designed for both wooden and metal installations. For metal doors and steel frames we use the Ajax-compatible spacer kit which prevents the magnet from being affected by the metal. We supply spacers as standard for metal doors at no extra cost.
Yes — there are configurations specifically for garage doors. For roller shutters we sometimes use a different mounting approach with a tilt-only mode. We assess at site survey and recommend the right configuration.
Yes. Strong neodymium magnets are commonly used by burglars to defeat older alarm contacts — they hold the magnet next to the sensor while opening the door, fooling it into thinking the door is closed. DoorProtect G3 detects abnormal magnetic fields and triggers a tamper alarm. This single feature stops a known bypass technique.
DoorProtect G3 itself is silent — it's a sensor, not a siren. Alerts sound through the system's siren (typically StreetSiren Plus G3 outdoors and HomeSiren indoors). Configure which sirens trigger and when in the Ajax app.
Shock detection sensitivity is adjustable. We tune it during installation to your specific door — sensitive enough to detect kicking attempts, not so sensitive that strong wind gusts trigger it. We also test extensively before signing off the installation.
Products typically installed alongside DoorProtect G3 in a complete Ajax system.
Most break-ins enter through doors and windows. Comprehensive entry-point protection is the foundation of any Ajax system. Free survey to design your coverage.
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