Please note that HHIC has issued a quick guide to variations in requirements across the UK nations.

There are:-

1. Carbon Monoxide Alarms –

(a) Domestic (including alarms for the deaf)

(b) Commercial and

(c) CO alarms for boats

2. Natural Gas Alarms – for the natural gas alarms please scroll down to the bottom of the page. 

1. Carbon Monoxide Alarms – (a) Domestic

For CO alarms for the deaf please see note at the bottom of the copy about domestic carbon monoxide alarms above note for commercial alarms.

As an extra safeguard, you can buy carbon monoxide (CO) alarms. We strongly recommend that you only buy CO alarms to EN 50291 bought from reputable suppliers NOT the Internet. Battery operated alarms are also available for travelling, or using in caravans, boats and tents. CO alarms can be purchased for about £20 from most DIY stores, some supermarkets or from professional merchants, engineers and energy companies.

The approval standard which now applies in the UK (and across Europe) is the

European Standard EN 50291

Main alarm requirements of all versions of BS EN 50291:

  • at 30ppm CO, the alarm must not activate (tested for at least 120 minutes)
  • at 50ppm CO, the alarm must not activate before 60 minutes but must activate before 90 minutes
  • at 100ppm CO, the alarm must not activate before 10 minutes but must activate before 40 minutes
  • at 300ppm CO, the alarm must activate within 3 minutes

From this it is obvious to see that CO alarms are very good at preventing death but are not ideal for preventing long term low level poisoning.  From our data we have found one person who died with a fully functioning alarm to EN 50291 that did sound but somehow she managed to ignore it. However, this is very, very unusual and we have not so far heard of another such death although we have heard of children sleeping through smoke alarms (similar noise see and also a man slept through a CO alarm but this luckily woke his neighbour who roused him see ).

We have come across a case where the alarm was to EN 50291 and did not alarm but the person felt ill with CO symptoms. Due to the difficulties of proof I don’t think this person was able to establish CO poisoning, which is so often the situation. However, people who are particularly vulnerable or worried should in our opinion buy a CO alarm that has a digital read out. Gas experts tell us that the only completely safe level of CO is nil.

To put this very simply, try to prevent CO being created in the first place by following prevention rules (see ) but buy a CO alarm to EN 50291 as an extra safeguard but be aware that it is more of a death alarm than an aid to health.

Note For recreational vehicle usage (caravans, motorhomes, boats) a new member of the standard family has some additional tests, this is EN 50291-2.  Camping in tents was not considered by the standards writers, as this was not a known hazard at the time of writing. Combined CO and smoke alarms There are now three fully compliant combined smoke and CO alarms on the market, Kitemarked by BSI to both EN 50291 for the CO function and EN 14604 for the smoke function. CoGDEM is the Council of Gas Detection & Environmental Monitoring, i.e. a club of manufacturers that make CO alarms etc. Reputable manufacturers such as Kidde and Sprue have models which CoGDEM has checked, and also Nest (not a CoGDEM member so not checked by CoGDEM). Up to a few years ago, it was impossible to design one combined unit that would meet both standards, but innovation has helped to change this situation. The optimum siting for a CO alarm and a smoke alarm might not always be identical. For example, in a good many homes the correct location for the CO alarm would be the kitchen if the boiler and gas cooker are both in that room. But it might not be appropriate to fit the smoke alarm there in case of multiple triggering during normal cooking processes. However, newer generations of smoke alarm use optical sensors which manufacturers claim are ‘toast-proof’. CoGDEM is still cautious about recommending combined smoke and CO alarms unless the application is for a smaller home such as a bedsit, studio apartment, open-plan home where the locations for both the smoke and CO alarm can be fitted together and usually on the ceiling. Innovations such as these are what the alarm industry does all the time, and the standards and test labs evolve to meet the innovation. Soon there will be a combined heat detector and CO alarm so that use in kitchens doesn’t cause false triggering of the fire detector (heat sensor).


CO Alarms for the Deaf




1. Carbon Monoxide Alarms – (b) Commercial  With regard to workplace CO alarms and detection, we suggest you ask CoGDEM at because it is difficult to give general advice with regard to the workplace.

1.Carbon Monoxide Alarms (c) CO Alarms for boats


safe-fire-directHelp Us – £1 Donation For Every Carbon Monoxide Alarm Sale

We have partnered with Safe Fire Direct to supply our visitors with discounted Carbon Monoxide Alarms to EN50291. These can be bought online or over the phoneTel. 0800 955 3600 and can be delivered to any address within the UK (postage charges apply).Use promotional/discount code COGAS2012 to receive 5% off your order & SAFE Fire Direct will donate £1 for every Carbon Monoxide alarm sale made using the above code.Note Please enter promotional/discount code COGAS2012 at the basket stage to receive discount.

Manufacturers (in alphabetical order) listed below sell wholesale to DIY stores and supermarkets.

AICO ( , Tel. 0870 758 40, email: ) Offers sealed powered for life units which include the Ei208W and Ei 208WD series, they can be upgraded or supplied with RF modules to provide wire free connections between the alarms, so if one alarm sounds then all in the system will sound. Plus a range of hardwired mains powered alarms with and without digital displays, such as the Ei225EN, Ei261DENRC and the Ei262 series. Some AICO alarms can provide downloadable data and monitoring. There is a new alarm the Ei3030. To learn more about the Ei3030, please visit:

All AICO alarms are certified to BS EN 50291 and available from electrical wholesalers, heat and plumbing centres, etc. Full product details online visit

BRK/Dicon ( , Tel. 01452 887570, email Using the latest electrochemical sensing technology, BRK/ Dicon carbon monoxide alarms are designed for domestic use. The comprehensive range consists of mains or battery powered alarms. The alarms are packed with features and include a sensor that automatically self-tests and has a 6 year guarantee. All are certified to BS EN 50291. For full product details online visit

Ei Electronics (, Tel. 0151 298 1588, email:  Ei Electronics  manufactures in Ireland and the company is exclusively involved in the manufacture of  residential smoke alarms, carbon monoxide alarms and allied products. Ei Electronics wide range of carbon monoxide alarms include Ei 204EN , Ei 207 and Ei207D with LCD readout which shows CO concentration from 10ppm. All models are approved to EN 50291, and available from a wide retailers such as Amazon, Sainsbury’s, Wilkinson. Full details on

FireAngel (, Tel 02476 323232, email: ) FireAngel manufactures long lasting CO alarms for the UK market. The alarms can be powered by either a replaceable battery or sealed for life power pack. The alarms not only feature the option of a 7 year life guarantee, but on some models there’s the ability to run diagnostic reports to prove if an alarm was activated, at what level and when. The digital alarm will show low level CO readings (which can be dangerous over an extended period of time). They can be bought at leading retailers such as B&Q, Tesco, Robert Dyas, Mothercare or Boots. All products are certified to BE EN 50291 For full product details and ability to purchase online visit

Firehawk Alarms (by Fireblitz) & 01322 342238.  

Fully sealed for life Carbon Monoxide alarms offering 5 years (CO5B), 7 years (CO7B) and 10 year (CO7B-10Y) as well as digital display version (CO7BD)

Firehawk alarms utilise the Figaro sensor and have sealed lithium batteries from Fuji or Ultralife, brands you can trust will power the alarms for the intended life.

The Firehawk CO range are approved to BS EN50291:2010 + A1:2012 and meet the requirements of Part J of the Building Regulations and the regulations in NI, Wales and Scotland. 

Further details including data sheets at

First Alert (, Tel. 01452 887570, email ), From the manufacturer of the world’s first smoke alarm, this concise range of CO alarms include 3 products powered by a replaceable battery. The entry product is compact and lightweight; the digital alarm shows current CO levels on screen and the combined CO and smoke alarm offers dual protection from smoke and CO poisoning. The First Alert range is available in retailers such as Robert Dyas, Makro and B&Q. All products are certified to BE EN 50291. For full product details online visit

Honeywell Analytics ( , Tel: 01202 708643, Email: ). Honeywell provides the new range of XC series carbon monoxide alarms. The XC70 has a 7 year life and guarantee while the XC100 and XC100D have a 10 year life and guarantee.

The alarm is officially approved and Kitemarked to EN50291:2010 parts 1 & 2.

For more information visit

For instruction booklet please click here.

All units benefit from a number of new features including:-

“Ventilate*” pre alarm function, low level monitoring mode,

memory function, upgradable to wireless connectivity and

completely sealed and tamperproof (IP44 rated)..

*The “Ventilate” pre alarm function, if required, needs to be manually activated by  the user when they first turn the unit on (see manual) and then will flash the blue ventilate light once 25% of the full alarm requirement is reached (time and concentration). Eg, if 43ppm CO is present the blue ventilate light will flash after 15-23 minutes. This is effectively advising people to open doors and windows to “ventilate” the area as the level of CO is higher than it should be but not enough to trigger the full alarm.

The XC100 and XC100D also benefit from the new and unique “Action Text” feature which gives a clear indication to the customer of what to do/who to call in the event of a full alarm.

Kidde manufactures a fully comprehensive range of carbon monoxide alarms for the home, all of which are fully certified by BSI to EN50291-Part 1 and guaranteed for 10 years.  Furthermore, the 7CO and 7DCO models are certified to EN50291-Part 2, meaning they are approved for use in boats or caravans as well as the home.  Our range also includes models 10LLCO and 10LLDCO which benefit from sealed-in lithium batteries that last the full 10-year life of the alarm and never need to be replaced.  Completing the Kidde range are the 4MCO and 4MDCO hard-wired, inter-connectable CO alarms – when one alarm detects CO, they all sound throughout the home.  Models 10LLDCO, 7DCO and 4MDCO include digital LCD screens that show the CO levels detected at all times.  Finally, our Lifesaver branded 5CO model, guaranteed for 7 years, is also certified by BSI to EN50291-Part 1 and offers the same level of protection at our most affordable price.  Our CO alarms can be found online and in leading independent stores as well as national retailers including Argos, Homebase, Asda, Amazon and Costco.

For full details visit us online at or call us on 01753 766392

CoGDEM  CoGDEM is a trade association – this is the professional organisation that CO alarm manufacturers are members of, so that the industry can speak with one voice and standards can be maintained.  CoGDEM also represents manufacturers of other gas measuring instruments such as flue gas analysers and workplace monitors.


We do NOT recommend cheap black spot detectors because they do NOT have an audible alarm. There is no British or European Standard for black spot detectors, they only last a few months, and they have been found to be unreliable. An audible alarm could rouse you from a CO stupor and save your life.  At around £20, an audible alarm will save you money over its lifetime (5-7 years) compared with the black spot detectors that have to be replaced every few months.
Also, Ann Brennan aged 19, a Durham student, had a black spot detector and it didn’t save here from dying from CO. An audible alarm could rouse you from a CO induced stupor and save your life, or that of a loved one!

2. Natural Gas Alarms

If you need a natural gas alarm these are available from Honeywell – contact details: Honeywell Analytics
Tel: 01202 708643

Honeywell has the HF500.
This is a main powered device and is officially approved and kitemarked to the latest European Standard, EN50194.
Cost is about £80-£85 inc. VAT.
Do visit

Due to the type of sensor that is required for flammable gas detection, currently there seem to be no approved flammable gas alarms on the market that can run effectively from only internal batteries because the sensor uses too much power and would drain these batteries relatively quickly. The unit does therefore need to be mains powered or in some cases can be run from a 12VDC power supply (such as a car battery). Recently (Jan. 2015) we have been given more reasons for the lack of a plug in natural gas alarm. From a technical perspective, natural gas is lighter than air so will fill a room from the ceiling downwards. Therefore if a detector plugged straight into a socket this would be in completely the wrong place to detect this gas as plug sockets will either be at floor level in most rooms or perhaps at chest height such as in a kitchen.

A natural gas alarm needs to be installed within 12 inches from the ceiling to provide the correct protection and the EN50194 standard also indicates this.