Does anyone know of Zigbee Smoke detectors that you can Interlink in HA? If one goes in alarm, I want all my smoke alarms to sound the alarm. Is that possible?
Any advice in brand/type is welcome
I am using a skyconnect/ZBT-1
You can add them all to groups in ZHA or Zigbee2MQTT
or just use HA Groups
Actually, it is very good question. If you have big house, interconnected smoke sensors make sense and they should work without any layer of software, like ikea bulbs and switches works. Or phillips hue.
This brings more security, because if is central system down for some reason, people still will be warned.
Here in the UK it is mandatory to have interlinked smoke detectors, not using software, either wired or wireless
I think Nest alarms use a combination of BLE and wireless. Not sure how reliable Zigbee would be - I imagine the coordinator would have to be working. Simply binding the alarms like lights and switches might be a tall order.
Mine are triggers in Alarmo, so if one goes off the whole alarm system chimes in to make sure you know there’s an issue 
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I assume that’s new builds? My house was built in 1662 and doesn’t have anything standard in it (no 2 doors are the same size!) - we use Zigbee smoke detectors.
Yes, I think so:
England and Wales – Building Regulations Document B (Volume 1)
These regulations cover new builds, materially altered dwellings, loft conversions and certain building extensions for standard dwellings.
All dwellings should be provided with an alarm system to at least Grade D1/D2, Category LD3 – this means the installation of mains powered alarms with an integral back-up power supply within the escape routes of the property (i.e. hallways and landings). In addition, the Regulations also require a heat alarm to be installed in any kitchen areas where the kitchen is not separated from the circulation space or stairway by a door.
The Regulations state that optical smoke alarms are generally more suitable for installation in circulation areas (hallways and landings) adjacent to kitchens. Heat alarms are recommended for kitchens.
All alarms should be interconnected to ensure audibility throughout the property in event of an alarm being triggered.
The Regulations also reference the British Standard BS 5839-6:2019 and recommend that an alarm system is installed in-line with this Standard.
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Greetings Evert,
I see this out there.
You might be able to find more with a search.
Tips on Searching for Answers & Duplicate Topics in the Forum.
Would such a thing exist for ZHA?
Or are there any other zigbee smoke detectors that have multi device grouping without another hub?
These use 868 MHz RF for the interlink. The RF link is automatically configured when the detectors are added to a z2m (or any other supported coordinator) network. The interlink is otherwise completely independent of zigbee and will work just fine even if the coordinator is down. I assume this fulfils the “not using software” requirement for interlinked detectors.
Not sure if that is an answer to the original question? There is no way to trigger an alarm using zigbee, so they can’t be “interlinked in HA”. The interlinking is fully automatic and independent of both z2m and HA after the initial interview is finished.
The detectors expose a few sensors via zigbee which can be used for automations/monitoring in HA: smoke, tamper, test, temperature, battery. The “smoke” sensor can probably be used to trigger external actions in HA, like calling an alarm number or similar.
Note that the temperature sensor is primarily for detecting fires. Both resolution and update frequency are too low to be useful under normal condtions.
There’s also a 230V version: Schneider Electric W599501 control via MQTT | Zigbee2MQTT
I have no experience with that one. One interesting fact to be aware of tis that it is physically larger than the battery powered detector
Reading about those, I think they need a hub too.
No, the zigbee hub is optional. You can interlink them manually if you want to. But that doesn’t make much sense IMHO.
And the hub is never required for interlinked operation, even when it was used to link the the detectors. I have tested that by stopping zigbee2mqtt, disconnect the zigbee dongle, and then push the test button on one detector until they all chimed. Worked as expected.