Fire Alarm Systems

[PerpetualLeakingRoof]

Hi,

I'm currently rewiring our house and while I have all the floors up etc etc i was thinking I would install a fire alarm system as the house currently has very poor protection.

I know that you can get smoke detectors that can be wired together but I was thinking the system we need to provide what I would consider an adequate level of protection is probably too complex for this system. The house is three story with a cellar (which will be a work shop so I would like a detector down there as well).

The way I see it that makes for 5 detectors - one on each floor and one in the kitchen. Does this sound reasonable?

I was thinking of going for a system like this http://www.sdfirealarms.co.uk/shop/4zonetwinflexplusfirealarmkit-p-444.html?cPath=27_86 which supports four zones of which I would probably use three: kitchen, main house, work shop. I assume that you can chain detectors like you loop lights?

Many thanks for any help or recommendations.

 

[breezer]

its up to you.

to be a true fire alarm are you aware it should be wired in heat resistant cable, it will need testing in its life time (every 3 months if its for insurance, but its not)

so i ask you this.

is it worth you spending that much when you could install as you said interlinked smoke detectors wired in 3 core and earth

 

[Steve]

I dont think that panel is meant for a house. It would consume more energy anyway, and you dont want that. Four interconnected mains + batt backup alarms would be sufficient.

Besides that panel is about £400.

 

[RF Lighting]

You can buy additional sounders for normal domestic smoke alarm systems if you think the sound levels will be insufficient.

 

[PerpetualLeakingRoof]

Sounds like the consenus is that it's not really worth it.

The cheapest centrally controlled system I can find is this http://www.discountfiresupplies.co.uk/product/125/145/Premier-Elite-2-Zone-Fire-Alarm-Kit at about £220 but then I would need to add about another £70 for the cable as if I installed this system I would wire it in fire resistant cable.

Simple interconnected fire alarms are going to set me back about £100 + cable (assuming I go for heat and smoke detectors). Is there a limit to the length of the interconnects between this type of smoke detector as I could easily be approaching 100m of cable in the system?

Thanks for the help and making me see sense gently

 

[mattylad]

Some security alarm panels also have a fire circuit & can AFAIK sound differently if the fire circuits goes off.

You may also consider replacing your security alarm with a panel/sounders that do do that.

As for heatproof cables, personally once a fire has been detected in a house & it's gone off I don't see the need for it, you are generally aware of it before the cable gets near a fire.
(Mind you I'll be wiring mine in FP200 (ish) because I have loads - lol)

 

[RF Lighting]

You only have to use fire resistant cable (which is different to heatproof cable) for the sounder circuit on a 'proper' fire alarm system.

You can wire the detectors in twin and earth if you like. Although it is generally accepted as good practice to use fire resistant cable throughout.

 

[scott1980]

You only have to use fire resistant cable (which is different to heatproof cable) for the sounder circuit on a 'proper' fire alarm system.

You can wire the detectors in twin and earth if you like. Although it is generally accepted as good practice to use fire resistant cable throughout.

All has to be FP now, both sounder and detection circuits.

 

[mattylad]

DOes that include domestic properties to though?

 

[breezer]

wouldnt think that matters, its the alarm that needs to be installed to regs, not where its installed (In this debate of FP200)

 

[RF Lighting]

You only have to use fire resistant cable (which is different to heatproof cable) for the sounder circuit on a 'proper' fire alarm system.

You can wire the detectors in twin and earth if you like. Although it is generally accepted as good practice to use fire resistant cable throughout.

All has to be FP now, both sounder and detection circuits.

When did this change?

 

[scott1980]

Came in with BS5839: 2002.

Includes mains supplies to the system aswell.

As for domestic properties, if the system has to comply to 5839: 2002 then yes, it should be wired in FP as per the above.

 

[tim west]

You only have to use fire resistant cable (which is different to heatproof cable) for the sounder circuit on a 'proper' fire alarm system.

You can wire the detectors in twin and earth if you like. Although it is generally accepted as good practice to use fire resistant cable throughout.

Thats true as when we did a job for a house conversion into flats when you were still able to do so before being certified as fire alarm engineers we went the whole hog and wired it all in FP200 only to be told by the fire officer who came round to certificate the job that we could have done it as above

 

[scott1980]

Perhaps you should refer the fire officer to section 26.1 of BS5839:2002:

"It is not normally possible to predict, with any accuracy, those areas of a building in which fire can or cannot occur. At the design stage, the exact route that cables may follow may also be unknown. Therefore to ensure that cables used for the critical signal path (see 3.13) remain operational for an adequate duration, cables with an inherent ability to resist attack by fire need to be used throughout such critical signal paths"

Section 3.13

"Critical Signal Path:

All components and interconnections between every fire alarm initiation point (manual call points or automatic fire detector) and the input terminals on, or within, each fire alarm device"

Statements to the effect of those above are repeated on a few occasions throughout the standard...

 

[RF Lighting]

Thanks for that. Interesting stuff.