Number Of Smoke Detectors

[Guest Cerberus NI]

We're required to do it should it be a required system in a house. Every bedroom or sleeping area shall have a smoke inside of it, and all are required for tandem ring. The general guideline for a bedroom/sleeping area is any room that can be closed off that contains a closet inside of it.

The reason for having them inside the rooms, is imagine if little Timmy is playing inside of his room with matches or something, or a fire starts inside a closed room, the amount of time it would take for a smoke alarm to go off adjacent to that room would compromise a person's escape time, as well as property damage prior to the brigade getting there.

We're even required to put one on each end of a long hallway (10M), in addition to the regular sounders, each head of our units is required to have an 85 db or louder sounder inside of it, with an audible level of 80db or 25 db higher than the location's ambient noises. We can have a standalone fire panel, or a combination intruder/fire panel, provided it carries all the proper listings and wiring methods are maintained using proper fire resistant/low toxicity jacketing on the cables.

I just find it somewhat shocking and apalling that GB seems to be behind the times on this subject. Inform me if I'm wrong.

I can install all the CO detectors in the world into a premises to detect incomplete combustion products, but what happens should the person suffocate on the smoke or toxins produced by burining plastics and other common materials first?

Like I said, inform me if I'm off base, since I don't work in GB.

It all comes down to the mis match of standards that exist in regulations covering fire detection. With regards to private dwellings in the UK then it's mains detectors with battery backup (unless you are in Northern Ireland where back up is not required) linked together so that one goes - they all go.

BS5839 (part 6) ,which relates to residential properties as opposed to commercial, comes in 6 grades ( A to F). A is your 24 vdc fire alarn system down to F which is battery powered detectors. Intruder systems come in on grade B.It all depends on whether you are in a single family dwelling or a sheltered housing scheme as to which catagory is required.

With regards to audibility,it's 65dB in general areas,75 dB at bed heads and 5 dB above ambient noise which persists beyond 30 seconds.In an industrial situation you can use 240 VAC sirens as secondary indication but these must only run when the process is in operation.The supply to these must be interuppted when the machinery stops.Your 20 dB above ambient is quite a step up - the difference between 85dB and 95 db at one metre is painfully noticable!!

I would be with you on CO's - as a secondary detection they are spot on but not as a first and only means.

The little "Timmy" scenario is not a reason to fit detection in bedrooms (although it is a good scare technique) as the audible alarm given by little Timmy would be quicker than that of the detector installed in the room.Those who die in their beds in the event of a fire are in the (large) majority of cases killed because they had not any operational detection outside the area of the fire (kitchen/living area), and so suffer the silent death of toxic inhalition (however the installation of linked detectors throughout gives you audibilty in a bedroom with the door closed should one of the others in the area of risk activate - this would be the main aim in installing in a bedroom)).Provided you have installed and maintained the detectors installed in the escape corridors then you should have ample time to get out.With regards to property damage and the brigade,their main concern is to get anybody out then contain and finally extinguish the fire.I can assure you it doesn't matter whether it's fire or water - your dwelling is going to be in need of serious repair!

Please excuse the ramble as I'm off this week and have been sampling my Guinness and Baileys!

[ABC]

I have residential fire, which is a whole ball of wax different from commercial, and of course, I'm sure you're aware of the required vs. the nice to have systems.

Our residences seem to have a whole lot higher standards in regards to fire alarm requirements. Right now, we're required to even have all bedroom mains circuits installed on arc-fault breakers. I'm just somewhat shocked that the required and minimum systems accepted in a single residence is so lax. I'd be worried about detection times in sections of a house separated by partition walls and having doors closed (such as the guest bedroom in my place) and detection behind those doors.

The Timmy scenario wasn't meant to be a scare tactic, but the theory still applies. Have a fire start, smoulder, whatever, behind a closed door, a detector on each level alone will not detect said event until it builds, I'm sure you agree on that. Also factor in an electrical issue, electric blanket, anything in that room, even if you're sleeping in that space, a detector in that space would be of absolute benefit irregardless.

As far as our audibles, the detectors can have a minimum of 85db sounders internally, and we're critiqued to a 80db at bed level (less than a meter off the deck) and depending on the area, such as mechanincals or the like is when they pull out the 20db rule, if the 80db can't be met by the detector itself.

Of course, we have provisions for dedicated spurs and breakers for fire alarm equipment, which depending on the install, could be a dedicated fire panel, or an intruder/fire panel. For the most, the LV fire alarm smokes are held in higher regard than the mains, as to reliability and function by all the inspectorate involved with the trade here.

The only thing that is somewhat different is heat detectors, thermostats, and rate of rise devices are absolute in not being called life safety devices, and not allowed on any mandatory system, unless the area involved dictates them (again, in absolute terms).

Of course I'm not going to mention commercial, which includes multi-occupancy spaces, hotel, hospital, and other specifically mentioned spaces in the code book. Factor that with disability acts and other standards, it's a mess, but at minimum the standards are black and white, with no overlap or debate as far as the absolutes go.

Like I said, I'm just a little shocked that GB is so lax in some of these matters, as the standards that you mentioned went out of favour about 20 years ago here.

[Guest]

Must admit it does baffle me as to why a bolt on the ceiling smoke is recognised by BS and smokes added to a fully maintained NSI/SSAIB alarm are not?

*QFA.

If smokes on intruders were to BS then there would be a lot more of them installed as I know there are plenty of houses with an alarm and no smke detection. Most intruder companies wouldn't think of doing mains operated smkes for various reaons (especially since part p). Also, a smoke on the alarm is tamper protected and theoretically maintained anually by a competent engineer with the alarm system, a standard mains smoke will probably never have the test button pressed in it's entire life, never mind every month. A smoke connected to an intruder system can't just be un-noticably disconnected either.

I'm sure someone knows why, I've never looked into it tbh. If they were to BS then there would be a hell of a lot more homes with BS compliant fire detection systems installed (mine being one)!

[Adi]

QFA.

[Guest]

So really then, a decent sounder base for intruder smokes such as the Exodus and a battery built in, job done?

Suppose both have pros and cons, but only one is BS compliant so that's that anyway.

[Guest Cerberus NI]

*QFA.

If smokes on intruders were to BS then there would be a lot more of them installed as I know there are plenty of houses with an alarm and no smke detection. Most intruder companies wouldn't think of doing mains operated smkes for various reaons (especially since part p). Also, a smoke on the alarm is tamper protected and theoretically maintained anually by a competent engineer with the alarm system, a standard mains smoke will probably never have the test button pressed in it's entire life, never mind every month. A smoke connected to an intruder system can't just be un-noticably disconnected either.

I'm sure someone knows why, I've never looked into it tbh. If they were to BS then there would be a hell of a lot more homes with BS compliant fire detection systems installed (mine being one)!

To be 5839 (pt1) all the cabling would have to be in FP or equivalent.However,it would be better you utilise the intruder alarm systems to meet Grade B 5839 (pt6).As you say Stuart,it takes away the tamper element that we all know happens with the mains ones - I check bungalows for a housing scheme quarterly that have mains interlinked detectors and out of 80 detectors I can guarantee 75% of them will be off (one tenant has removed the 5 of them,polyfilled the holes and papered the ceilings in embossed paper - the mains was still live!!).

[Paul Giles]

As I understand it, it's because the stand alone jobbies have a built in sounder.

If a fire should destroy the cable between the alarm panel and a fire detector or the internal sounder, the system cannot alert occupants to the danger..... The external unit could sound but may not be audible in a rear bedroom.

I agree that the alarm powered sensors are far superior, but I can see the weakness in the system too.

At least the intruder would sound on tamper, the mains one would not make a sound.

[cdosrun]

How would the system be regarded if mains powered (battery backed) detectors were installed throughout, and then all wired back to the panel on the interlink? I have been looking at doing this for when I move to a new place; it is possible to connect the interlink from each alarm through a few components so that if one goes off, they all sound, but the burglar alarm will only display those detectors actually in alarm.

EI also do alarms with remote hush and test that could be connected to the outputs of an alarm, such that on unsetting after a fire, they could automatically hush the sensors.

Would this comply with all the relevant standards for current domestic installs?

Andrew

[Guest Cerberus NI]

Stuff it - I'm sticking to Part 1!!!This domestic stuff is messy.

[esp-protocol]

Hi.....

would just like to sneak in my first two penneth........

Intruder systems come in on grade B.

Grade B systems require fire proof cable.......

Intruder systems come under Grade C.

To meet part 6 for Grade A,B,C,D systems (systems incorporating a central power supply or independent mains detectors incorporating battery backup) the standby supply has to last for 72 hours, hence the average security system won't comply unless you install a larger battery.

In domestics you need a minimum 85dB(A) at the bedroom door, 75dB(A) at the bed head only applies in BS5839-1 - commercial/hotels/boarding houses etc.

The average three bed semi, providing it is no higher than three storeys needs a Grade D minimum system - mains powered smokes/integral batteries, all linked together, Category LD2 - installed in all circulation areas forming part of the escape route, and in all rooms/areas that present a high fire risk to occupants.

As with all things these days, everything is risk assessment based and "you" need to decide the risk areas that need protecting.

But I do agree, getting to grips with domestic system design is a complete pain in the 'arris !!