Help please with fine print on location of smoke alarms

[neverwas]

I am fitting new, linked smoke (or heat in kitchen) alarms. After reading the words of wisdom here and elsewhere I am (famous last words) fairly confident about wiring them. But I thought I might as well also meet the current regs on their *location* and that has me stumped.

Approved document B1 looks easy peasy for a small Victorian terrace: interlinked detectors on each storey within 7.5m of each room.

On the other hand lots of other documents (eg the 2002 Onsite Guide) say there should be an alarm within 3 metres of any bedroom door. That's a bit tougher in a typically long, thin house. But, thinks I, it's not a problem in practice as I was always planning on a detector in the small bedroom at the back of the house (because it doubles as study with assorted PCs often left on unattended). But hang on: does it count if it is *within* the bedroom rather than in the circulation space outside? I'd be very grateful for pointers to the answer to that question.

On the third hand, if I put a detector outside the door to that bedroom but within 3 metres it will be less than 3 metres from the bathroom door and several guidance documents say that is a no-no. Can anyone point me to the source of that rule and/or whether it trumps the "3 metres from the bedroom" rule please?

I guess the underlying principles in this are: you need alarms in enough places to detect fires, and near enough to people to wake them, but not where false alarms will lead people to disable them. But the way it is articulated in the guidance has defeated me. And while there may be rules for the pros which avoid the Catch 22, there's no way I'm giving the BSI £180 for BS 5839-6:2004. (So much for making the law accessible!)

[TheScullster]

"neverwas" wrote

snip...

I bought AICO alarms who had an obliging technical department. Might be worthwhile trying the manufacture?

Phil

[Owain]

IMO no, as if inside a bedroom the sound would have to travel through two bedroom doors to be audible at the bedhead in an adjacent bedroom.

Near bathroom doors may give rise to false triggering from shower steam.

Personally I would put a detector/sounder in every bedroom (a) to ensure adequate volume at the bedhead, (b) to provide the earliest possible alarm from someone smoking in bed. Unless you have a *very* long thin house with a windy corridor or beams across the ceilings you /probably/ then only require one above the stairwell in the corridor.

IANAfiresafetyofficer.

Owain

[Dave]

Fire brigade came out this week to change our smoke detectors and we got a detailed talking to. If I was in your position, I wouldn't put a smoke detector in a room. The one we have on the landing can be triggered by me opening the bathroom door, as others have said, I have even set off the one downstairs by making some well browned toast. If you have a long landing, there is nothing wrong with putting more detectors in it.

We got told to close all doors at night etc., but the one thing they didn't mention was keeping a torch at the side of the bed. Wife was away for 3 months and I was in my hobby room when I had a power cut. You have no idea how difficult it was for me to find my way down stairs. It must have took me enough time to get unconscious from the smoke. Normally, you feel your way round, but with 2 open bedroom doors (though it was dark, I don't tend to close the doors until bedtime, for airing reasons), I was totally lost.

Put another sensor up. As I said above.

Believe me, unless you are severely deaf, you will hear them through a door. And the over riding factor of having a smoke alarm is to warn you of smoke coming from somewhere else, other than the room you are in.

Dave

[neverwas]

Thanks for that good idea. Email sent to Kidde today.

[neverwas]

Thanks but I don't think that is really the issue here. The alarms have to be interconnected so if the smoke arises within the small bedroom anyone in the other 2 bedrooms will be able to hear the alarm outside (less than a metre from their doors) and another on the ceiling below. I may yet fit alarms inside those bedrooms too.

I may well do so. But even in a small house it is more than 3 metres from the bedroom door to the alarm I have fitted above the stairwell. So I'd still like to know if that meets the requirement to have one within 3 metres of the bedroom in the circulation space - if there is such a requirement - or if I am just failing to read the documents properly. (Methinks I really do need to get out more/get on with all the other jobs.)

[neverwas]

Thanks for the response. All good stuff so far as I can tell. But my head scratching is partly because I simply cannot put an alarm within 3 metres of the bedroom door which is also more than 3 metres from the bathroom door.

In the end I'll probably put one near the circulation space near the bedroom door as we get little steam from the bathroom. (But I suppose that may change if I ever get around to insulating the bathroom.)

[The Natural Philosopher]

No, its useless there by and large.

You need to talk to either the fire officer at the local fire sttaion, or a BCO.

Smoke alarms are not really there to detect fires, so much as to detect when exit routes are in danger of being blocked by fire IIRC..

That's why they are generally in CORRIDOORS. I have one in a bedroom ONLY because that has an en-suite that is only accessible via that bedroom. Could get trapped in the en-suite you see.

I have two on upper landings, and both will go off if steamy bathroom doors are left open: thats the reason for the bathroom rule: people might turn the buggers off if they false alarm too much.

Fire regs at this level are all about getting people safely out of blind alleys before they get trapped. And having window big enough to rescue people through as well.

Bsically draw lines from every room to the outside..your escape routes.

Fit alarms past the first barrier between any living space and that route, and all along the route at about 3 m intervals.

So lets say you have several bedrooms and a bathroom on a floor, and the staircase is your exit route: you put an alarm on the landing somewhere..tow if its more than 3m long, sited as far away from te bathroom as you can..then every landing down the staircase should have another one - or more, all the way to the front door/backdoor/sidedoor/garden door.

The only time you alarm a room is if it is an escape route from a room beyond.

[The Natural Philosopher]

Put it as far away from the bathrom as you can, and fit extractor fans.

[John Rumm]

For what is it worth, I had three interlinked alarms in the last house - one on each floor. The first and second floor ones were within three meters of all the rooms on that storey - including bath and shower rooms. Never had any problems with steam triggering them - even before I fitted humidistat controlled fans to the bathrooms.

Note also the ionisation and the optical ones behave differently with non smoke triggers.

[John Rumm]

Non maintained emergency lights are cheap and easy to fit these days - just feed them from the nearest suitable lighting circuit. A couple in strategic places makes a massive difference to your ability to navigate in the dark or possibly when your vision is obscured. It means you can always have light when you need it.

[Dave]

I am rapidly coming round to that idea, but it is the long days and total fulness of inertia that is stopping me. :-(

It was a real eye opener that I could not navigate my own house that shocked me though. We have only been in it since 1978 :-(

I will buy some mains backed up (charged) lighting that will come on in the event of a power cut.

Thanks

Dave

[Hugo Nebula]

On Fri, 11 Jul 2008 13:57:20 GMT, a particular chimpanzee, "neverwas" randomly hit the keyboard and produced:

BS 5839-6 says, "Most unwanted alarms occur during cooking activities. Ionization chamber smoke detectors are significantly more sensitive than optical smoke detectors to products that occur during toasting of bread, and during frying and grilling. Thus, optical smoke detectors are less likely than ionization chamber smoke detectors to respond to fumes from cooking. This makes the optical smoke detector much more suitable than ionization chamber detectors for installation in hallways and circulation spaces into which kitchens open. It is important that this information is conveyed to householders, particularly by those responsible for advising householders, including, for example, fire and rescue services.

"On the other hand, optical smoke detectors are much more prone than ionization chamber smoke detectors to produce false alarms if exposed to steam. Optical smoke detectors are also generally more likely to produce false alarms when exposed to dense tobacco smoke. Ingress of dust can also cause instability of optical smoke detectors, and result in constant false alarms. Thus, if optical smoke detectors are installed close to poorly ventilated bathrooms, shower rooms, kitchens or rooms in which people smoke heavily, false alarms might occur; in each of these cases, other than close to kitchens, ionization chamber smoke detectors would be less likely to produce false alarms. False alarms can also occur if smoke detectors are installed in dusty spaces, such as roof voids, and, in such situations, if smoke detectors are necessary, ionization chamber smoke detectors are preferable".

"Optical smoke detectors should not be sited in close proximity to rooms from which steam may issue, such as poorly ventilated bathrooms, shower rooms and certain kitchens".

'Close proximity' may be less than 3m, depending on the air flows & where the steam is likely to go. If not, then an ionising detector may be better. Or proper ventilation to the bathroom.

[neverwas]

Many thanks. That's good enough for me as an explanation of the "3 metres from a bathroom" 'rule'. I'll put an ionisation detector outside the bedroom near the bathroom (and an optical inside the bedroom as it is a potential escape route).

It leaves me feeling a bit depressed though at the compliance cost of reading the guidance. What you quote seems to me easy enough for a layman (who takes care) to construe. But I have so far not found a local library which admits to having BS 5839-6. And I have searched all the London boroughs via

[Dave]

BS. I couldn't download it or even find it on the web, so in desperation I went to my local library. They gave me a brand new library card and a pin number, but I was told that I could only download part of it and that I couldn't print out most of it. What is the point in having a British standard if you can't work to because of lack of access?

Dave

[Bob Eager]

[Fred]

Hello,

We have an optical alarm downstairs which has frightened us a couple of times in the middle of the night by going off for no apparent reason. The intervals between false alarms are some months but I'm not eagerly awaiting the next one. Is there any reason I cannot swap it for an ionisation one on the basis that the ion one will not have so many false alarms

Thanks.

[Owain]

Is it battery powered? Battery alarms tend to 'fail' in the small hours when it's coldest and the battery voltage falls.

Owain

[Fred]

No, mains.