Zigbee door sensor
Zigbee Door Sensor – alternate view
Zigbee Door Sensor – detail view
Zigbee Door Sensor – close-up

Zigbee Door & Window Sensor UK – Magnetic Contact (Home Assistant)

(274 customer reviews)

£9.99

A Zigbee magnetic contact sensor for UK doors and windows. Reports open / closed state instantly to your hub – no polling, no delay.

  • Magnetic contact sensor – reports door / window open / closed state instantly to your hub
  • Native Zigbee 3.0 – pairs with Home Assistant (Z2M, ZHA), SmartThings, Hubitat and other Zigbee 3.0 hubs
  • Fully local control – no polling, no cloud delay
  • CR2032 coin-cell powered with well over a year of battery life
  • Slim profile and 3M adhesive mounting – no drilling required

In stock

SKU: ZM-CG205 Categories: , Tags: , , , ,

Description

A Zigbee 3.0 magnetic contact sensor (model ZM-CG205) that detects whether a door or window is open or closed. Reports state changes to your hub within 200ms of the magnet separating from the sensor body, so automations can fire instantly – not after a 30-second polling interval like cloud-based sensors.

Two-piece design: the main sensor body mounts to the door or window frame, the small magnet mounts on the moving leaf. When the leaf opens, the magnet moves away, the reed switch inside the sensor opens, and the sensor sends a Zigbee message to your hub. No app polling, no internet round-trip, no delay.

Practical uses

  • Front-door arrival notifications – send a phone notification or trigger a light scene when the front door opens.
  • Back-door security – if a back door opens after midnight, sound a siren or turn on all the lights.
  • Window-open heating control – pause underfloor heating or radiator TRVs automatically when a window is opened.
  • Garage / shed monitoring – know when the garage door opens, even if you’re not at home.
  • Drawer / cupboard alerts – useful on medicine cabinets, drinks cupboards, or any drawer holding valuables.
  • Fridge / freezer left-open alerts – mount on the freezer door, get a notification if it’s been open for more than 2 minutes.

Hub compatibility

Generic Zigbee 3.0 device using the IAS Zone cluster (the standard for contact sensors). Works with any Zigbee 3.0 coordinator:

  • Home Assistant (Zigbee2MQTT or ZHA) – fully local, recognised as a generic contact sensor with open/closed binary entity.
  • Philips Hue Bridge – paired as a third-party Zigbee 3.0 device. Appears in the Hue app for routines.
  • SmartThings – paired via the Generic Zigbee Contact Sensor driver.
  • Hubitat – built-in contact-sensor driver, works locally.
  • Aqara Hub M2 / G3 – works as a third-party Zigbee device.

Battery life

The CR2032 coin-cell included in the box lasts well over a year in typical use (10-30 events per day). Heavy use (50+ events per day, e.g. front door of a family home) reduces this to around 9-12 months. The sensor reports battery percentage to your hub, so you can set an automation to notify you when it falls below 20%.

Installation

  1. Peel the protective tab from the included CR2032 battery to activate the sensor (some shipments require manually inserting the battery – check the packaging).
  2. Put your Zigbee hub into pairing mode.
  3. Press the small button on the sensor body for 5 seconds; the LED blinks rapidly to indicate pairing.
  4. Once joined to the hub, mount the sensor body and magnet using the included 3M adhesive pads. Maximum recommended gap between the two pieces: 15mm.
  5. Rename in your hub app, assign a room.

Specifications

Specification Detail
Model ZM-CG205
Protocol Zigbee 3.0 (ZHA / Zigbee2MQTT compatible)
Detection Magnetic reed switch
Max gap 15mm between sensor and magnet
Battery CR2032 coin cell (included)
Battery life 12-18 months typical
Mounting 3M adhesive (included)
Hub required Yes (any Zigbee 3.0 hub)
Cloud dependency None (fully local)
Certification CE, UKCA, RoHS

What’s in the box

  • 1 × Zigbee door / window contact sensor
  • 1 × Magnet
  • 1 × CR2032 battery (pre-installed)
  • 2 × 3M adhesive pads
  • Quick-start guide

Additional information

Type

SM300Z, SM312Z
Brand

Samotech

Frequently Asked Questions

What does the Samotech Zigbee Door Sensor do?

The Zigbee Door Sensor is a compact two-piece contact sensor that detects when a door, window, drawer, or cabinet is opened or closed. It instantly notifies your Zigbee hub, which can push real-time alerts to your phone or trigger automations such as turning on lights, sounding a siren, or sending notifications.

What’s the detection gap on the Zigbee Door Sensor?

The sensor has a detection gap of 5mm — meaning the two parts of the sensor must be within 5mm of each other to register as "closed". Anything wider than that triggers an "open" event.

What battery does the sensor use, and how long does it last?

The sensor runs on a single CR2032 coin cell battery (included), with battery life that lasts well over a year under typical use.

Which platforms is the Zigbee Door Sensor compatible with?

The sensor (Tuya TS0203 family) works with Zigbee2MQTT (Z2M), ZHA (Home Assistant), and Tuya — paired through any Zigbee 3.0 hub.

Where can I install the Door Sensor?

Install the sensor on doors, windows, drawers, cabinets, mailboxes, or any other moveable component you want to monitor. The compact 50 × 25 × 11 mm form factor blends discreetly into most door frames.

How do I install the Door Sensor?

The package includes 3M adhesive stickers — clean both surfaces, peel and stick the two pieces of the sensor in alignment (one on the moving part, one on the fixed frame), pair with your Zigbee hub, and you’re done.

What automations can I trigger with the Door Sensor?

Through your Zigbee hub, contact events can trigger any automation your platform supports — lights on when a door opens, alerts when the front door opens after midnight, fridge/freezer open notifications, garage door status, and any combination.

Manual

Technical Data

Zigbee Contact Sensor

274 reviews for Zigbee Door & Window Sensor UK – Magnetic Contact (Home Assistant)

4.5
Based on 274 reviews
5 star
66
66%
4 star
21
21%
3 star
11
11%
2 star
0%
1 star
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1-10 of 274 reviews
  1. Stephen T.
    Verified owner
    (0) (0)
  2. Anonymous
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    (0) (0)
  3. Sohan W.
    Verified owner

    Worth it

    (0) (0)
  4. Anonymous
    Verified owner
    (0) (0)
  5. Ajay O.
    Verified owner

    An average choice

    (0) (0)
  6. Karthik Z.
    Verified owner
    (0) (0)
  7. Tarun B.
    Verified owner
    (0) (0)
  8. Pradeep D.
    Verified owner

    Does what it claims

    (0) (0)
  9. R. Isaiah
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    (0) (0)
  10. Martin F.
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    (0) (0)
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