Advice - UK smoke alarm sensors

Hardware
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UK legislation has over the years changed to make the requirements for types and quantities of smoke/fire alarm sensors more strict. The following link gives a reasonable background to this and refers to the current main applicable legislation BS 5839 part 6.

It should be noted that for an existing single family dwelling you should be able to get away with any level of sensor including various ‘smart’ smoke alarms.

However, if the dwelling is being rented out, or is a new build or is being extended and therefore subject to ‘building regulations’, or having significant modifications/renovations also making it subject to building regulations, it would seem highly likely these regulations will apply.

The purpose of this post is therefore to raise this issue as it would affect the possibilities for adding ‘smart’ smoke sensors.

Some aspects should be straight forward, for example for kitchens you need a heat type smoke/fire sensors and not a more common smoke particle only sensor. Other issues are more complex such as ‘non tamperable batteries’ and/or mains powered with battery backup and the biggest potential issue - interconnection of multiple sensors.

For interconnection of multiple sensors the preference is for wired connections but I believe that a wireless connection can be used if it is not WiFi and likely not Zigbee, Z-Wave or other smart home standard. The goal being that any interconnection method not be open to tampering or interference.

As such I do not believe any so called smart home smoke sensors would meet these interconnection requirements.

Since over time more properties would be new builds or have an applicable extension, then more and more people could be come subject to this legislation.

Note: As an example Amazon Nest Protect is being discontinued and was not compliant since its interconnection is WiFi based. As far as I can see it would be ok to have a ‘smart’ sensor system which used WiFi or Thread, or Zigbee for smart management and reporting if it also had a proprietary interconnection purely for triggering all of them to sound an alarm.

It seems many/most traditional security alarms that also support smoke sensors and of course traditional fire alarms would already support these requirements. This is not surprising since likely the legislation was drawn up by people from these fields.

However -

  1. What if any smart sensors are currently available that could meet these requirements? (And have they official certification?)
  2. Are any smart sensor firms in the process of making their products compliant?

Note: Whilst this legislation is UK specific, meeting these requirement would I feel also still be suitable for other countries and might also have aspects required in other countries.

Obviously my posting here is with the intent that the sensors would be viewable in HA.

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Hi,
There’s a few issues here:

  • Standards.
    Scotland is different - e.g. the old Google Nest Protect was broadly compliant in the UK, but specifically excluded from more stringent (and better IMHO…) Scottish Fire and Smoke Alarm Legislation 2022.
    Basically, Scotland believes that the risk within kitchen areas is higher requiring a sensor.

  • Market size verses risk.
    Smoke alarms are marketed to electrical contractors (cheap, quick to fit), and consumers (safe, no false alarms), neither of whom seem that interested in connected products. If you develop a clever system, it is likely to be rejected by pros (can’t be bothered, takes too long), and consumers get scared of complexity quickly.
    Worse, install a complex system incorrectly and someone could die leading to a major liability. What if a 3rd party Zigbee coordinator prevented a fire alert being signalled between sensors? You can see the urge to close systems to ensure you have control.
    So, small return, low probability but high impact risk - suggests a very specialised market, and high cost (which is exactly what commercial fire alarms are).
    The best hope I have here is Matter/ Thread increases the market size and reduces risk (as you’ll remember Thread started as Google Weave with the Nest Protect).

  • Testing.
    Real safety critical systems need to be tested. UK regs changed a couple of years ago and now commercial systems need 6-monthly professional checks, not just forging signatures on a test clipboard sheet (not that any office ever did that).
    Consumer kit seems leave this to a tamper evident battery cover (can’t refit it without a battery, although a discharged one works fine…).

I’ve seen a few products that are little more than novelty items - the Fibaro Z-Wave Smoke sensor complies with EN14604, but looked like a part fell off a philishave razor! Bought two, didn’t deploy them as they looked like toys and at the time openHAB Z-Wave ate batteries.

Fire Angel and Kiddie offer interlinked sensors, with some even offering a “hub” gateway to a cloud app. These seem expensive, not local, and useless without mains power, Internet, and all the things that fail in real fires.

There’s a few hacks using opto-couplers to monitor the interlink cable between wired alarms, but again, I didn’t deploy them due to a risk of an insurance company denying a claim.

Some voice assistants and CCTV offer alarm sound detection - e.g. Ubiquity distinguishes intruder and fire alarms as different sensors (not tested them). These have the advantage of low insurance risk, but will the detection work? How about locally with UPS and reliable alarm signalling when the fire is caused by an electrical issue?

I help manage a community facility that is required be law to have a commercial fire detection system, checked 6-monthly, and serviced with other controls like emergency lighting.

The first system was fitted by a stupid electrical contractor looking for maximum profit (optical sensors in all shower areas - guess how that went? :clown_face:), the second has been much better with one wired bus, combined addressable sensor/ sounders and UPS (Infinity ID2 Panel + Zeta sensor heads). Addressable sensors means you know in the log what happened, avoiding running about a potentially burning building with many keys checking rooms.

Even, then I’ve not got the alarm connected to HA as the relay output is required to disable a passenger lift (and as a Chartered Engineer, I’m not hacking a safety critical system even it would be easy with RS232 and RS485 ports). The best I’ve come up with is a Zeta relay output module (basically a sounder with a dry contact output) or use Unifi sound detection.

A similar product area is home care alarms, or “granny fall pendants”. I’ve experience of a housing provider still using a system based on analogue telephony which will be turned off in 2027. They will eventually move to a new platform which is much closer to HA than you’d expect. Tunstall Lifeline Digital is a hub with a 4G modem for alarm signalling, and Z-Wave 868 MHz comms for sensors. The integration is for Alarm Receiving Centres not homes!

FYI, I’ve written about care home integration before after some professional involvement…

Hope this is of interest, even if I can’t see any usable products at the moment!

If this helps, :heart: this post!

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This begs the question… In a domestic setting, why would you want smart alarms?

Off the top of my head I can only think of two possibilities:

  • Turn on lights if there is a fire during the night (how many homes have emergency lighting?)
  • Send a text/email alert to someone outside the home.

I suspect that both of these come into the “because I can” category of home automation.

I did struggle through the long, involved process of integrating my Nest Protects. The integration worked, but I abandoned it quite soon after because there didn’t seem to be much point.

If it had been able to test the alarms, that might have been useful, but the only definitive way to test a smoke alarm is to blow smoke into it - which is what they do as part of those six-monthly tests.

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Yes - I agree, and remote notification of an issue at home has been useful for me in the past. Water leak sensors spotted a problem before the ceiling was damaged badly.

One of the hopes for the HA 2025 roadmap is sensors like fire / flood can be registered in a semantic model allowing an automation to be suggested with options. Sort of auto-detect + blueprint + druid/wizard.

I’m sure we’ll think of more as the classification of entities expands (the main one will probably be suggesting lighting controls with motion sensors in the same room/area).

You can buy aerosol “smoke in a can” that works with optical sensors (don’t think ionisation, and not heat rise) but it was expensive the last time I looked (a RS smoke machine kit is >£1k), and even the cheap(er) cans need a “funnel on a stick” to direct the spray. It was easier to pay a contractor to test and certificate than buy / 3d print the kit.

It is a real shame that Alphabet / Google / Nest has such a short attention span. The Nest detectors offered something new and useful. Let’s hope others like Samsung Smartthings don’t give up so easily.

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From a domestic user’s perspective, without any regard to regulatory requirements, I can imagine these reasons for a lightly smart smoke detector:

  • alarm groups, depending on where smoke is detected, I may not hear the triggering smoke detector - so getting that relayed to all others would be nice
    • triggering other sirens (shared with burglar alarm, CO alarms or water leak detectors) would be beneficial (again I wouldn’t hear a detector in the basement, while being in the first storey)
    • relaying alarms to the smartphone when not at home
  • being able to switch off false alarms (this is something regulations frown upon) quickly and easily, without hitting it off the ceiling with a broomstick
  • having a nice and easy overview for the battery status for all detectors (early notification, not waiting for the beeps - and knowing for sure which of them is complaining about its battery)
  • and yes, enabling emergency lighting would be an added benefit
  • reasonable prices still a hard requirement (call it cheap)
  • formal certification appreciated

The smart things obviously should not get into the way of regulation compliant (I’m willing to turn a blind eye to the requirements not to disable alarms via smart features and the tamper proof battery compartment) functionality, local-only, local alarming, battery powered.

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Yes, forgot about that one. :grin:

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+1

Never done that, honest.
I use a ladder and a big hammer :hammer: ! :grin:

Commercial fire alarms make it hard to lockout sensors or zones for exactly the reasons you expect.

The best you can do quickly is cap a sensor head with a shower cap (“recycled” from hotels, natch), or use the covers supplied with them when painting or creating dust. This also means the lockout is more obvious and less likely to be forgotten.

At least centrally powered systems don’t have alkaline batteries that cool down at 3AM so the voltage saggs, and the device starts beeping randomly with just enough volume to wake but not communicate.

Kit should have a light level sensor and the smarts to beep for errors during daylight. The Nest devices flagged issues early and made it a feature.

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the reason for a connected smoke and co2 alert is simply this, 1 being alterted when not at home, 2 stop potential hazard systems. 3 cal fire department when not at home, once the alert has been received and verified. nevertheless, the system should work without the smart component…