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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Technical Advice => Topic started by: Davro on January 29, 2008, 08:11:23 PM
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I have just installed extra detection in a building and found that some of the old detection was not wired in!!! I know it was installed 2 years ago by another company but for some reason not connectd into loop.(firedex 3000).Question is the all cables are in pyro and fitted correctly so i did the same with my fp cable and then connected the detectors that were not on the system all was o.k but am i at fault now because they just slung their cables in and i connected it,making me the last person to deal with it and will it comply with fire regs.
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no your not at fault so long as whatever work you have done complies with BS5839-1 regardless of the state that you find it in.
issue a modification certificate that only holds you responsible for the work that you have done.
in this case fit detectors not the state of the existing wiring.
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This should have been spotted before now, as each detector should have been tested at least annually!
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Yes your right they should have been spotted by service guys but i think the fault was did not have the software to introduce them on the loop.Major big company if you know what i mean and if they cant do it who can i thought.
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I have been looking at a new alarm system in a large office building. draka Firetuf soft skin cable has been used, it hangs vertically in 5m high pipe ducts without any support, lies across none fire resisting false ceilings without any support (thats easy specifically covered in BS5839) and where there is no false ceiling metal loop strips have been screwed to the underside of the floor slab above through which the cable loops every 4m or so. A group of 6 cables descend 3m to the panel from the ceiling and have no support except they are tied together with plastic tie wraps and swing freely when pushed. I think the plastic tie wraps are also supporting the cables- and again that is clearly wrong.
I have raised it as unsatisfactory in the risk assessment but the installer is challenging this.
I have referred to the cable manufacturers website but little positive help, looked at BS5939 and BS7671 and "Modern Wiring Practice" hoping to find something specific on spacing for cable supports in concealed and exposed surfaces.
Modern Wiring Practice refers to standard PVC - clip every 250mm horizontal /400mm vertical for exposed and 4m horizontal / 5m vertical in concealed places for unsupported PVC.
Any comments or guidance please?
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Prof., I presume you are now only asking about the distances between fixings since the other problems are covered by 5839.
The standards won't recommend a general fixing distance because such figures might only be applicable to some versions of cable. It is up to each cable manufacturer to advise specific maximum fixing distances for their product to achieve the fire resistance required in BS.
I've had a quick look on Draka Firetuf website but can find no reference. You might need to phone their technical support to find out more.
It would have be better if 5839 had said something like the cable fire resistance capability must be based on fixings at a maximum of 600mm horizontally and 900mm vertically, for example.
You could always turn the tables on the contractor and ask him to provide written evidence of the cable fixing spacings required for that type of cable before you will amend your risk assessment!
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Kurnal ,
Same old story the holy bible was written and soft skinned cables were not really allocated much attention as when I started on the 14th edition mineral was still the one to use.
I know the 17th is up now and it needs an amendment since soft skin cables have basically taken over.
To my mind there should be a commercial element to this regs , and in particular fire alarms should be separate entity as well.
I would look at the mineral section as this will only give you the possible ammo you need.
You could also see installation spec requirements the cable company has , might be able to achieve not installed as per manufacturer's guide for performance.
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Thanks for your replies. It really goes back to similar arguments to those Thomas Brookes was making in the thread on recognising the technical details of heat and smoke detectors during a fire risk assessment.
I dont particularly want to go nit picking during a fire risk assessment and ought to have confidence in the certificates presented to me and put a tick in my box. But if the installation and commissioning engineers have not done their job right and left something as blatantly obvious miles of cable just resting on the top of the false ceiling matrix bearers awaiting the tiles being put in, and every alarm cable just tied together descending several metres to the panel swaying gently in the breeze then something has gone wrong.
Then when you point it out engineers go apopleptic and defensive and make it worse by saying they always do it like that and if fire officers, BCOs and landlords dont complain who the hell are you to criticise and what qualiications have you got? Tel me whats wrong with this and show me where it says so?
Well its easy to shoot them down in some cases where there is a spefific breach of BS5839 ( false ceilings and plastic cable ties) but the unsupported cables appears to be a nightmare because each manufacturer has different rules based on their own products fire tests.
I would be grateful for any general guidance on this for soft skins- a bit like we have for mineral and pvc - to use as a rule of thumb to indicate when I should blow the whistle.
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Could we not now use Artcile 38? The new version of 5839 discusses firefighters getting tangled in cables following the Harrow Court incident. The current and latest edition of the fire detection and alarm standard is
BS 5839-1: 2002+A2: 2008. The following clauses relate to the changes made as a result of the Harrow Court recommendations:
26.1(A2)Commentary: Unless cables are supported in such a manner that they remain supported for the duration similar to that for which the cable itself can survive a fire, early failure of the circuit might occur because of strain on terminations as a result of collapsing cables.
26.2 Recommendations, (f) Note 9 (A2): Experience has shown that collapse of cables, supported only by plastic cable trunking, can create a serious hazard to firefighters, who could become entangled in cables.
46.2(b)(5): Note 2 (A2): Serious shortcomings in cable support that could result in collapse of a significant length of cable in the event of fire should also be regarded as a major non-compliance.
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.......Then when you point it out engineers go apopleptic and defensive and make it worse by saying they always do it like that and if fire officers, BCOs and landlords dont complain who the hell are you to criticise and what qualiications have you got? Tel me whats wrong with this and show me where it says so?........
This is a common problem. One way to deal with it is to only deal with your own customer. i.e. don't answer questions from anyone other than the person paying your bill for the report.
If your customer passes your report to, say, the installers, then that is between your customer and the
installers. Don't get involved.
If you start talking with the installer then you are left with only one option i.e. to prove everything you've put in the report. This only gives you more work and him/her free training!!
If you are confident in what you have put in your report then there is no problem. If someone disagrees with something in your report it is up to them prove it wrong.
Playing the good guy and just trying to help some people, doesn't always work.
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Thanks Dr Wiz. Good advice, though often the client puts all of us in the same jar at a pre handover meeting and shakes the jar up. He is only interested in what comes out at the end.
Jokar- the only problem I have with the new clauses in BS5839 is that my risk assessment is under the RRO, firefighters are not relevant persons under the order ???
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Yes I know, but if they are sent in to save relevant people then that is a subtle change. In addition the facilities, the FA system, is there for the use of firefighters, zoning etc, therefore you could apply A 38.
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I looked into this a while back and found that the cable fixings distances are down to vibrations as measured by the HSE, in a normal enviroment it is recommended that the cables are fixed every 300mm and 450mm, if the property is next to a railway line they may need to be closer etc.
As for ownership due to being the last person to work onthe system, doesnt 5839 say you may not add to the non compliance of an existing system, makes your case a bit more difficult, where the cables part of the system but just linked through, if so you have not introduced a non compliancy, if not then I would say you have.
Also should they have not been found when the site was inspected for the first time and the owners informed?
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Greg,
Surely vibration resistance is not the only criteria. We are talking about fire resistance and surely the spacing of fixings is relevant for this.
I was once told by a cable manufacturer that when a soft skinned fire resistant cable is attacked by flames a chemical reaction causes the skin to 'carbonize' in some way which then provides a fire resistant, but brittle, covering on the cable. However this brittle skin is then very susceptible to cracking open (and losing fire resistance) if it is moved too much.
If the above is correct, then surely the manufacturers have done tests to confirm the maximum fixing distances to ensure the cable does not move and crack open in a fire?
I can understand that vibration could make the 'cracking open' problem worse but surely the cable has to be properly fixed for fire resistance purposes in the first place?
I was also told that the original soft skin fire resistant cables were only tested for fire resistance when affixed to a solid wall because some of the heat generated in a fire would be absorbed by the wall and not the cable. Evidently they didn't tell anyone this. It was subsequently found that cables in fires where flames could 'lick' all around the cable couldn't meet the fire resistance required. Evidently the manufacturer eventually rectified this problem.
Manufacturers are selling fire resistant cable with no clear instructions as to how it should be used. Why do they do this? Have they got something to hide? If a cable fails in a serious fire will they look for ways of getting out of liability and blame the method of installation?
I believe installers should contact their cable suppliers and insist on being given a full set of installation criteria for that cable that will ensure it meets it's fire resistance in a fire.
Is there any other product sold in the fire industry without any installation instructions?
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http://www.uk.prysmian.com/en_GB/cables_systems/energy/catalogue_pdf/lv_pdf/fp200_gold.pdf;jsessionid=EE1D3CYLY4LQBFYKJO4SFEY
300mm Horizontal, 400mm vertical for FP200, I doubt the others will be a lot different.
Paul
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Thanks goodsparks that is really useful practical advice. And to everyone else who has assisted with my query. If I can find out how to attach pics I will post a couple of real eye openers I have come across this week.
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Good work, Good Sparks!
It does disappoint me that in the example you have found, that the note for fixing distances really only relates to using the LSOH clip because the 'note' relates to this. It doesn't confirm if there are any differences in using any other method of fixing. The manufacturers should be aware of all the typical methods of installing their cables and provide advice according to each method.
I agree with your thoughts that it is likely that other cable types would recommend similar fixing distances and it is likely that a similar fixing distance would apply to alternative fixings for this type of cable. But how can anyone be sure? I feel It should be made clear in black and white for such a critical application
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Thanks goodsparks that is really useful practical advice. And to everyone else who has assisted with my query. If I can find out how to attach pics I will post a couple of real eye openers I have come across this week.
Open a free account at Photobucket and upload your pictures to there. It will then give the you correct [img] tag to insert the photo on a post on here - just copy & paste it, thats how I do it
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Im lucky in that the contractor that we use for installation runs horizontals' in 20mm metal conduit with metal saddles because it saves labour hours.
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The installation of the cables will fall under BS 7671 - several parts.
Reg 560.8.1 requires that cables installed for "safety services" to be mounted to maintain circuit integrity in fire conditions for as long as possible - that suggests firmly clipped to me so the when BS 5839 takes over and mandates metal cored clips then you still need to meet the requirements of BS 7671.
Examination of the whole of regulation group 522.8 - other mechanical stresses suggests in several regs that cables should be adequately supported both horizontally and vertically and that minimum bending radii are abserved. It does not stipulate minimum's as these would depend on the cable size.
Reference to Guidance Note 1 (Selection and Erection) shows in Table G2 that for cables exceeding 9mm and not exceeding 15mm diameter (typical soft skinned) then horizontal clipping distance is 300mm and vertical distance is 400mm.
So there appear to be lots of reasons why loose laid soft skinned fire alarm circuits don't comply with either BS 7671 or BS 5839
Regards
Owen
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Initially, It doesn't matter what any general purpose regulations might say, or what instructions for similar products might say, I would not be happy until the manufacturer of the cable I was using, provided clear, concise, written instructions as to how to use their product properly, and specifically what the maximum fixings distances are for my method of fixings to achieve the stated fire resistance. I would only then consider any general purpose recommendations and, if necessary, modify the manufacturer's instructions if the general purpose recommendations required closer/more effective fixings. It is incumbent on a product manufacturer to provide the instructions for use required.
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Owen, loose laid I would take it means laid on joists or inaccessable areas, such as closed in ceilings, it would be safe to assume that the joists/inaccessable areas would support the cable at least as well as a cable clipped to the underside of the joist or closed ceilings, even following all the guidence.
But Wiz, how are the cable manufacturers expected to know of every possible installation, they can only give guidence based on their controlled lab tests, all an installer can then do is prove he followed the guidence and requirements of BS5839, even then if he hasnt taken into account all the potential risks he may still be at fault and up in front of the judge.
I think the term "as far as reasonably practical" comes into use here, in old languange "common sense"
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The BS recommends fire resisting cables should be used, with enhanced protection required in some circumstances. Where enhanced fire resistance is required it is usually due to phased evacuation or in a building with different alarm zones. In these cases all alarm cabling is critical and installation standards must be upheld to the highest standard.
But how important is it in a simpler building with conventional evacuation strategy? What do we achieve by enforcing the highest standards of installation? I would like to explore why and what this achieves. What is the liklihood of a poorly installed soft skin cable with inadequate support burning through or failing as a result of exposure to a fire before the alarm has been raised and evacuation complete? If the cable serves sounders as well as detectors then it appears to me to be particularly critical- and most do nowadays. In the old days I remember higher standards were applied to sounder circuits than detector circuits. Now everything is on the same loop but the loop and the isolators make this arrangement more resilient. Could a burn though affect more than the immediate vicinity of the fire?
Owen, loose laid I would take it means laid on joists or inaccessable areas, such as closed in ceilings, it would be safe to assume that the joists/inaccessable areas would support the cable at least as well as a cable clipped to the underside of the joist or closed ceilings, even following all the guidence.
Yes you could argue that in the situation you describe we have a detector protecting the area beneath a ceiling with the cables laid on top of the ceiling. If the ceiling offers fire resistance, it will protect the cable. But presumably there will also be a risk of fire and other devices in the ceiling void as well, and ifwe could take account of the fire ressitance of the ceiling the BS would state this
But Wiz, how are the cable manufacturers expected to know of every possible installation, they can only give guidence based on their controlled lab tests, all an installer can then do is prove he followed the guidence and requirements of BS5839, even then if he hasnt taken into account all the potential risks he may still be at fault and up in front of the judge.
I think the term "as far as reasonably practical" comes into use here, in old languange "common sense"
Every day I see alarm systems installed by engineers I respect that do not come anywhere near the 300mm/450mm guidance for FP200 cables. Usually I turn a blind eye because poor standards are indeed the norm and I only rock the boat if something is strikingly bad. But I am starting to wonder if the industry needs to get its act together a bit more and the Trade associations, Building Inspectors and Fire Authorities ought to look a little bit closer too.
Thanks to the responses to this thread we already have an understanding of the underlying reasons for the poor standards.
BS5839 is far too vague
Manufacturers do not give clear instructions on how their cable should be installed
BS7671 is not specific as to whether its guidance applies to fire alarm cables and does not reflect the development of soft skin cables
There is a lack of understanding in the Industry
Commisssioning engineers do not have to look at cable workmanship as part of the commissioning process.
How much does it matter though?
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But Wiz, how are the cable manufacturers expected to know of every possible installation, they can only give guidence based on their controlled lab tests, all an installer can then do is prove he followed the guidence and requirements of BS5839, even then if he hasnt taken into account all the potential risks he may still be at fault and up in front of the judge.
I think the term "as far as reasonably practical" comes into use here, in old languange "common sense"
Greg, I don't mean every variation possible.
I would suggest it would be something like:
a) When the cable is affixed to any fire resistant surface that is anything other than horizontal, fixings should be every (say) 500mm.
b) When the cable is laid on or under a horizontal surface that partly exhibits less fire resistance than the cable itself, it must be affixed to a structure of at least equal fire resistance as the cable every (say) 400mm.
See, that wasn't difficult! Why don't the cabl;e manufacturers say something similar? I think they are hiding something!
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The BS recommends fire resisting cables should be used, with enhanced protection required in some circumstances. Where enhanced fire resistance is required it is usually due to phased evacuation or in a building with different alarm zones. In these cases all alarm cabling is critical and installation standards must be upheld to the highest standard.
But how important is it in a simpler building with conventional evacuation strategy? What do we achieve by enforcing the highest standards of installation? I would like to explore why and what this achieves. What is the liklihood of a poorly installed soft skin cable with inadequate support burning through or failing as a result of exposure to a fire before the alarm has been raised and evacuation complete? If the cable serves sounders as well as detectors then it appears to me to be particularly critical- and most do nowadays. In the old days I remember higher standards were applied to sounder circuits than detector circuits. Now everything is on the same loop but the loop and the isolators make this arrangement more resilient. Could a burn though affect more than the immediate vicinity of the fire?
Owen, loose laid I would take it means laid on joists or inaccessable areas, such as closed in ceilings, it would be safe to assume that the joists/inaccessable areas would support the cable at least as well as a cable clipped to the underside of the joist or closed ceilings, even following all the guidence.
Yes you could argue that in the situation you describe we have a detector protecting the area beneath a ceiling with the cables laid on top of the ceiling. If the ceiling offers fire resistance, it will protect the cable. But presumably there will also be a risk of fire and other devices in the ceiling void as well, and ifwe could take account of the fire ressitance of the ceiling the BS would state this
But Wiz, how are the cable manufacturers expected to know of every possible installation, they can only give guidence based on their controlled lab tests, all an installer can then do is prove he followed the guidence and requirements of BS5839, even then if he hasnt taken into account all the potential risks he may still be at fault and up in front of the judge.
I think the term "as far as reasonably practical" comes into use here, in old languange "common sense"
Every day I see alarm systems installed by engineers I respect that do not come anywhere near the 300mm/450mm guidance for FP200 cables. Usually I turn a blind eye because poor standards are indeed the norm and I only rock the boat if something is strikingly bad. But I am starting to wonder if the industry needs to get its act together a bit more and the Trade associations, Building Inspectors and Fire Authorities ought to look a little bit closer too.
Thanks to the responses to this thread we already have an understanding of the underlying reasons for the poor standards.
BS5839 is far too vague
Manufacturers do not give clear instructions on how their cable should be installed
BS7671 is not specific as to whether its guidance applies to fire alarm cables and does not reflect the development of soft skin cables
There is a lack of understanding in the Industry
Commisssioning engineers do not have to look at cable workmanship as part of the commissioning process.
How much does it matter though?
Hear, hear, Prof. I'm with you on all of the above,
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I saw a new variation yesterday in a posh shopping centre. One of my clients has just completed their fit out to a stringent spec from the landlord. The landlords common areas fire alarm cables are clipped to the UNDERSIDE??? of a galvanised 300mm wide metal cable tray that is used for security and data traffic. Hundreds of metres of enhanced protection cables fastened onto the bottom of the tray with plastic tie wraps.
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Sounds like a case of :
' Physician heal thyself'
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quick blast through the ammended standards today and noticed that any cable unsupported over a significant length should be regarded as a major non compliance.
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Any idaea of what a significant length may be?
If carrying out a 6 monthly service on an old installation pre 1988 with PVC T&E for the detector circuits and soft skin for the sounder circuits how many of you guys would see this as a problem and bring it to the attention of the client? Would you ever upgrade it without the panel falling over first? If the panel did fall over and you replaced it would you replace the detector circuits at the same time or leave the PVC in situ??
No trick questions just trying to identify a consensus. Seen a new panel installed recently on horribly substandard wiring and no comment on commissioning cert.
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Personally , I would advise them of the actual facts of what they have got , based upon a reasonable system .
I would advise them to make budget allocations for the future to bring it in line within the requirements at present which we hope are the best at this present time .
However there seems to be a trend outside the fire companies to bash the owner of the installation with 'It don't comply to 2002 standards'.
If you are realistic and honest with people they seem to take it on-board .
If you have advised on matters and they only want to change the panel , fine then the panel is changed and correct paperwork is issued , I have been to some jobs after a so called upgrade and the original installation and kit was better than the cr*p that has replaced it.
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Do we all agree then that it is bad practice to rely on plastic cable ties as the sole means of securing and supporting soft skin fire alarm cables?
Since these are used in 90% of new installations that I see- including buildings with phased evacuation policies- should the fire industry as a whole be doing something about it?
Does anybody else comment on it or is it me being far too picky? And how could we tackle the problem?
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If my engineers only used plastic tie wraps only they would be made to go back and redo with metal ones.
Not wanting to point the finger but it is mainly electrical contractors that use plastic, they dont know any better and rely on the fact that there never will be a fire and if there is they will be long gone or blame the next poor sod who connects in a few detectors to help out a client ...
Easy way to tackle the problem would be for the cable manufacturers to mark the cable at 300 and 450 intervals and print on the cable the required P clip or metal wrap part no.
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Do we all agree then that it is bad practice to rely on plastic cable ties as the sole means of securing and supporting soft skin fire alarm cables?
Since these are used in 90% of new installations that I see- including buildings with phased evacuation policies- should the fire industry as a whole be doing something about it?
Does anybody else comment on it or is it me being far too picky? And how could we tackle the problem?
It doesn't comply with the recommendations as providing a fixing of equal fire resistance as the cable itself, so it is obviously bad practice. No argument.
You are not being picky, you are doing your job correctly. I would highlight it very strongly on any commissioning I carried out.
By highlighting it, the problem will be tackled.
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....Easy way to tackle the problem would be for the cable manufacturers to mark the cable at 300 and 450 intervals and print on the cable the required P clip or metal wrap part no.
I like it Greg. Maybe the marking could be a V for vertical fixing spacing and a H for horizontal fixing spacing.
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....Easy way to tackle the problem would be for the cable manufacturers to mark the cable at 300 and 450 intervals and print on the cable the required P clip or metal wrap part no.
I like it Greg. Maybe the marking could be a V for vertical fixing spacing and a H for horizontal fixing spacing.
Only if you live in Milton Keynes ?
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....Easy way to tackle the problem would be for the cable manufacturers to mark the cable at 300 and 450 intervals and print on the cable the required P clip or metal wrap part no.
I like it Greg. Maybe the marking could be a V for vertical fixing spacing and a H for horizontal fixing spacing.
good idea but gives them another excuse to whack the price of a drum of cable up more..high enough already..