Fire alarm feed

[supasparxs]

Hi Guys,
Is there a reg stating that a Fire alarm must be supplied with a fire proof cable?

I did a EICR today and the building has a sub main in 2.5 T&E in a metal trunking to a fuse isolator then MICC from the isoator to the local spur (10 meters away) which was local to the panel

I have looked in Ch 35 and 560.10 but can't find an actual reg

Richard

 

[telectrix]

nothing in 7671. it has been common practice for a few years to mains feed fire alarm panels in MICC or FP200. but any reg. on this will be in the fire alarm BS5839, might have forgot the number . DOH.

 

[Darkwood]

Reading 351 note 1 explains you need to follow statutory authorities requirements, as well as this check 560.5.2 this suggests the safety source (battery back-up for example) needs to maintain supply for adequate duration in fire conditions, most times they are in the fire panel but if external then cable needs to be fire rated, now the normal source (public supply) dosn't have this requirement, as your safety source can take over in case of fault or fire damage to supply cable, if you are using a 230v system then common sense would denote it requires all to be wired in fire rated cables but this system by its nature may not comply to local fire regulations.
Also as Teletrix says its the BS 5839 that you need to have at hand as that will give deeper insight to requirements.

 

[supasparxs]

Thanks guys,
I don't have a copy of BS 5839, but the refferences for the 351 note 1 and 560.5.2 should be enough

Richard

 

[Guest123]

BS 5839-1 states as a minimum "standard fire resisting cables are to be used for all final circuits to the fire system".

 

[telectrix]

but what is a final circuit re. a fire alarm.? is it the alarm detector and sounder circuits, or the supply circuit to the panel?

 

[Guest123]

but what is a final circuit re. a fire alarm.? is it the alarm detector and sounder circuits, or the supply circuit to the panel?

The alarm & sounder circuits are classed as "critical signal paths".

I take "final circuits" to mean just that, a final circuit supplying the alarm system from the LV mains.

 

[telectrix]

can't disagree, lenny. just was not sure of the definition.

 

[Darkwood]

Now here's the issue i have; as Lenny states it is a requirement in the Bs 5839-1 but the OP is doing an inspection under the scope of the 17th BS 7671 which dosn't give a written requirement for the query he has brought up but agree in the green book it has been ammended to express that the BS 5839-1 should be complied to in 560.8.1 / note1-(i), im on the thinking here that the OP should make the Fire Alarm circuit an exclusion from his inspection and should come under the scope of a Fire Alarm inspection cert.

A large majority of the sparkies i know dont carry or have ever used a copy of the BS5839 so only have the 17th and are unlikely to get a copy so this will mean they can't or shouldn't be doing a inspection on the supply to such a system and either make it an exclusion from the cert' or buy the BS 5839-1 and thus have the knowledge to properly inspect it.

Opinions please as this is the way i see it, im up for debate as thats the learning curve of life.

 

[sedgy34]

we wired fire alarm and from the lanlords DB to the panel its all fp (good practise) if its not a reg

 

[Darkwood]

In response to the final circuit definition under discussion, surely if it meant the supply from public source to panel then they would have included a regulation in the 17th to cover this simple point with regards to its need to be fire rated.

 

[Guest123]

I have a PDF but it's too large to uplaod here.

That does state categorically that under the current issue of BS 5839-1, both main supply cables and detection/sounder circuits should be fire resisting cables.


WRT the EICR, I would agree that an addendum to the report could be added excluding the fire alrm system from the scope of the EICR. Ordinarily a specialist contractor is responsible for the maintenence & testing of a fire alarm system so the supply circuit would fall under their scope.

 

[Darkwood]

Wasn't doubting you Len it was just the ambiguous wording of final circuit and because i dont either have a copy i cant cross reference the context it was written in so just asked but im also with teletrix in that i cant disagree really as it been a requirement, but just strange that they do cover all the other cables regarding the install in the 17th but dont mention the supply cable as a seperate reg' nor would it take up alot of space to include in existing reg's.

It does bring up an interesting point that you have agreed with me on that the supply cables are been routinely tested and inspected under the scope of the 17th by electricians who dont have the BS5839-1
Maybe worth its own thread to bring this point across to other members and see if they do indeed as i suspect test it under the 17th only.

 

[Guest123]

It is a bit of a grey area.

It is perhaps something that could be agreed in the 'limitations' with the client at the initial discussion stage. In the larger complex buildings, it may not be possible to isolate the supply circuit for testing purposes for a number of reasons.

Where possible I would include the circuit in my testing, I/R, R2, Zs etc, but, if it was found to be installed incorrectly then I would raise the point in my report, referring to the relevant standards, if the system was not under the wing of a specialist contractor.

 

[supasparxs]

Cheers Lenny,
by the sound of things the wiring is correct.
They have a 2.5 T&E supplying the isolator which then is wired in MICC to the spur and panel.

oh well never mind

however I have snagged them on discrimination
5 amp MCB in the DB and a BS1361 15amp fuse in the Isolator



has anyone else used the 2012 Amtec software?

 

[tazz]

Bs5839 changed in 2002, Mains feed to fire alarm panels must be wired in enhanced fire proof cable, this can be enhanced fp200 or piro. Mains feed can be off db now or essential supply db. A lockable double pole switched fused spur must used to feed the control panel located near by. Usual 17th regs apply to cabling such as protection by rbo/rcd etc where the control panel must have battery backup and warning incase of mains failure. A lot better than the old days of comming straight off the incoming with a BS88 fuse

 

[hillbillie]

I flagged up a non compliant fire alarm power supply in a PIR I did last year. The power to the fire alarm board came from a bit of 1.5mm wrapped around a screw on the blue phase busbar in a TP&N d/b! The busbar was fused at 200A if I remember correctly!

I replaced the supply cable with fp200 and took it back to a d/b in the switch room, thinking that I should ensure as much of the supply circuit as possible had added fire protection. I also used a metal enclosure and a porcelain jb to connect it to the fp200 the fire alarm company had put in place.

I saw the technicians from the fire alarm company the firm used and pointed out the problem and they just shrugged their shoulders and said they just connected it up to what was already there.

 

[supasparxs]

hmmmmmmmmmmm

some thing never surprise me

 

[tazz]

Hillbillie, can well believe some of the installations, seen them so many times. But this proves a good point were both BS standards do run together, and even before the days of rcds and rbos. The installation was fused as near to the incoming as possible, and correctly fused at the rate for the cable used.

Personally we always insist on a niciee contractor to supply all power to our fused spurs with full testing certs, as with any circuit

 

[Charlieelec]

The Majority of fire alarm engineers (istall and service) are not qualified sparks and such all companies that i know have it in there t&c's that the customer is to supply a spur (this now should be a double pole secret key fuze)

For the company that i work for any alterations to the mains needs a Zs reading to prove safe, this was done with the niceic.

and all feeds need to be dedicated from fuze board and now run in fire rated cable. Replacement does not need to be but spur should be replaced.

- - - Updated - - -

The Majority of fire alarm engineers (istall and service) are not qualified sparks and such all companies that i know have it in there t&c's that the customer is to supply a spur (this now should be a double pole secret key fuze)

For the company that i work for any alterations to the mains needs a Zs reading to prove safe, this was done with the niceic.

and all feeds need to be dedicated from fuze board and now run in fire rated cable. Replacement does not need to be but spur should be replaced.

 

[jaresquire]

Section 26.2 of BS5839-1:2002 with A2:2008 gives the recommendations for cabling. Generally standard fire resisting cables should be used for the mains supply, with enhanced required in some circumstances.
On the large commercial sites I attend a separate supply is made straight from the busbar, but quite often is still wired in singles from there !

 

[mgibson212]

Hi Guest123, you say you have a PDF of this could you send me it