Bs5839 1988

[JohnCunningham]

John@epl i pressume?

Ok I am a bit slow working out the initials.

Graeme I presume?

[Guest G.J.M]

Where in BS7671 does it say that? A 1982 PVC T&E electricial installation may well have smaller earth cables than a modern PVC cable but this in it's self is not reason enough to rewire an installation. The trade bodies (NICEIC etc) may well recomend this but that's their business isin't it?50 year old houses well that's going to an extreme now, that would be rubber cable which is considered dangerous so that would be good enough reason to have a fire alarm fitted! I don't think 15 year old (serviced) fire alarms are considered dangerous are they?

Luggsey-you don't really get my point so i will leave it.the rewire is somewhere and i remeber it from college . If i find it i will post a link.

Ok I am a bit slow working out the initials.Graeme I presume?

correct

[luggsey]

Luggsey-you don't really get my point so i will leave it.the rewire is somewhere and i remeber it from college . If i find it i will post a link.correct

Well if you explain the reasoning behind the arguement I might know what you were on about?

So far I have heard 15 year mentioned as needing a rewire, 20 year, 25 year and now 50 year........

Anybody have manafactuers data on the "life" of a correctly installed PVC T&E cable?

[esp-protocol]

Which again means you will recomend rewiring any installation you inspect (no matter it's age) unless it's a complete surface job as you won't be able to confirm every last bit of cable is installed to the regs, as I said earlier all inspections on installations should carry the caveat that wiring within the fabric of the building cannot be checked, thats' always been the case, things are not as simple as condeming systems due to age or inability to examine every last bit of cable, if I was the customer and you gave me a report that recomended replacing a 15 year old systems wiring simply because you couldn't visually check every last bit of cable I would show you the door and get another company in, this is the attitude most of my customers would show me if I recomended replacing expensive fire alarms with such reasoning. By all means be honest with a customer and tell them they "can" improve their system should they want to upgrade it to the latest spec but to write up a report on an older system saying it does not comply to the regulations would in my opinion be misleading a customer unless it was made clear to them they don't "have" to comply with these regulations. In my book that would be miss-selling and we all know where that leads!

Not really lugs.

Nope you cannot inspect cables buried in the fabric, but if the installation is in FP and you have no reason to think that anyone has gone to the trouble of joining and burying lengths of PVC in the fabric of the building, then apart from your caveat, which is correct, I would not suggest re-wiring the system to MI or any other cable.

At least if FP has been used throughout then you do not need to worry about diverse cable routes and routing through areas of low risk.

If on the other hand i saw an installation obviously still using PVC I would tell the client it doesn't comply and recommend re-wiring for all the reasons given above.

Unlike the FP installation, there is an increased risk the cables are not routed correctly and may contribute to a larger problem if a small fire took them all out.....

[luggsey]

Not really lugs.

Nope you cannot inspect cables buried in the fabric, but if the installation is in FP and you have no reason to think that anyone has gone to the trouble of joining and burying lengths of PVC in the fabric of the building, then apart from your caveat, which is correct, I would not suggest re-wiring the system to MI or any other cable.

At least if FP has been used throughout then you do not need to worry about diverse cable routes and routing through areas of low risk.

If on the other hand i saw an installation obviously still using PVC I would tell the client it doesn't comply and recommend re-wiring for all the reasons given above.

Unlike the FP installation, there is an increased risk the cables are not routed correctly and may contribute to a larger problem if a small fire took them all out.....

Well I do question the assumption that if the installation is in FP you have no reason to think..... Well I can honestly say that the last install I worked on done by some berk my last employer employed, he had used a link in T&E when rewiring a system with an analogue panel (It was a spur as well!). So to assume "all is well" with the type of wiring used is wrong IMO. You can no more condem a detection circuit wired in PVC T&E because it "may" have been badly installed then you can recomend rewiring an FP job because that "may" have been badly done.

As I already said if a system was installed to 5839-88 then there should be no reason to recomend replacing wiring because it "may" not have been installed correctly or was installed to an older version of the regs, unless you can demonstrate the failing of the system due to a failure of the installer to get it right then IMO you are barking up the wrong tree. Also just telling a client "it dosen't comply" is misleading without explaining what that really means, ie. the system is completly legal but I (the engineer) would "like" it to be wired to the latest spec to cover arses which don't need covering!! If the original install was ever proved to be faulty by virtue of wiring installed in the wrong way (within the fabric of the building) then the original installer is the one that would need butt protection big time!

I think we will continue to disagree on this point ESP because I don't agree with replacing/recomending replacing good (legal) wiring with new when there is no legal requriment to do so. Neither do I agree with telling clients "it dosen't comply" without a full and clear explanation of what that really means, ie. it dosent comply with the latest regs but it is a totally legal installation which you do not have to replace.

[Bill]

Don't shoot the messenger.... just explain to the judge why you know better than Mr Todd and the rest of the BSI Committee who have recommended better cables...........

Not sure that "better cables" is correct - "more appropriate cables" is nearer it.

From a purely electrical perspective, Twin and Earth has all the required performance characteristics necessary to ensure a reliable fire alarm installation. One of the primary reasons for the change in cable specs has to do with what happens in the event of a fire - e.g. the physical characteristics of the cable, rather than the electrical characteristics.

Twin and Earth cable does not have the heat resisting properties, or the toxic emmission properties required.

Really, the problem is not so much the standards changing, nor even the technology - rather our understanding of how to ensure the system remains of maximum benefit for the longest possible time in the event of a fire taking hold in a building is what drives the change.

Personally, I will always recommend upgrade to fire rated cable, because of the reasons above, and the probability that the system will operate for longer when an event occurs, and will increase the chances of sufficient warning being given - particularly in the case where a system is configured as short circuit fault, rather than the older short circuit alarm - and I've seen a lot of new detection retro fitted to old installations configured as short circuit fault (on Twin and Earth cable).

[Guest G.J.M]

one thing i am seeing more of with regards to grey twin and earth in use is that is definately more likely to be cut off by electricians if the building is having re-wiring done.

They put an inductance tester on it,get no response then proceed to strip out the cable. At least with red FP that won't happen.

As ESP has mentioned- a t+e cable could be running through a void which has no afd a has a fire. bye bye cable.

whats the point servicing a fire system if you are not prepared to point out all the non complainces to 2002?

ironically you are not complying with BS by not doing so during a maintenance.

You are leaving yourself wide open to the situation where if another company was on site(for what ever reason) or an inspectorate asking the customer why you have failed to point out all the non compliances.

At this point the customer won't thank you then for being a good guy and not telling him. It's the old no win situation-upset him telling him or upset him by not.

[luggsey]

This thread was about what to tell a client if his fire alarm is wired to BS5839-88 standards, not which sort of cable is best.

Some of the points raised are valid enough, FP is better for fire alarms then T&E, no arguement there.

What I disagree with is a blanket statement of "does not comply and needs rewiring" because it's 15 years old.

As I keep saying, make your client aware there are newer regulations which T&E cable do not comply with if you wish, or simply note on the paperwork it is a BS5839-88 system and leave it at that. It's still in full complience with the law and highly unlikely to be less safe then a newer install if installed correctly. To suggest to a client that their safety/property is at risk due to the wiring being BS5839-88 is simply scare mongering.

Just a passing thought, if a detection cable in a void that has no smoke detection is subject to a fire, the T&E will cause a fault to flag up on the panel long before the FP cable would, there are always two sides to everything......t&e cables in voids may in fact be safer then HR cables.......

Has anybody ever designed a detector cable that could be snaked all round a void or similar location to detect excess heat, hmm, have to think about that. A conductor that goes high Z when heated would fit the bill

[Bill]

This thread was about what to tell a client if his fire alarm is wired to BS5839-88 standards, not which sort of cable is best.

Some of the points raised are valid enough, FP is better for fire alarms then T&E, no arguement there.

What I disagree with is a blanket statement of "does not comply and needs rewiring" because it's 15 years old.

As I keep saying, make your client aware there are newer regulations which T&E cable do not comply with if you wish, or simply note on the paperwork it is a BS5839-88 system and leave it at that. It's still in full complience with the law and highly unlikely to be less safe then a newer install if installed correctly. To suggest to a client that their safety/property is at risk due to the wiring being BS5839-88 is simply scare mongering.

Just a passing thought, if a detection cable in a void that has no smoke detection is subject to a fire, the T&E will cause a fault to flag up on the panel long before the FP cable would, there are always two sides to everything......t&e cables in voids may in fact be safer then HR cables.......

Has anybody ever designed a detector cable that could be snaked all round a void or similar location to detect excess heat, hmm, have to think about that. A conductor that goes high Z when heated would fit the bill

Well - there is no immediate reason that a system installed for compliance with BS5839:1988 will not comply with the 2002 amendments - that's part of the point of the maintenance visit - to establish realiably whether or not there are non-compliances. The standard also states that systems should comply with the latest version of the standards in order to remain compliant (as well as have regular prescribed maintenance visits).

Fire rated cable is part of the standard - therefore Twin and Earth should not be considered suitable for any part of the system - however old - it makes the installation non compliant, is a defect, and needs notifying as such. As far as identifying systems installed using twin and earth during a maintenance or inspection goes, again, it is a defect, and needs notifying. At the risk of being cynical here, there are two aspects to the need to notify defects to clients.

One - the client needs to know that their fire alarm and detection system is lacking in some way against current standards and that they could (potentially) be leaving themselves wide open in the event the worst happens, the system fails to perform in some way, and they end up the bad guy through ignorance.

Two - and more directly relevant to most installers and maintainers is the fact that if some part of the system fails during a fire, or does not perform properly at all - AND the installer has failed to notify and record defects, it WILL be assumed that no maintenance has been carried out on the system. The installer can, and probably will, end up liable for the failure of the system. This is the original contractual clause - CYA - (Cover your //.B.W.F.//) - and would, you'd think, be the fundamental guiding principle of every installer to some extent.

As regards the cable in the void scenario - no. At least, no, not always. What happens in the situation whereby some "clever" engineer has stuck the end of lines in the panel? What if the cable goes open circuit rather than short? It happens. So, no, Twin and Earth is not safer than Fire rated cable - that's why the standard was amended.

Finally - yes there is a heat detection device like you descirbe - it's called a linear heat detector, and is essentially a run of heat sensitive "cable" connected to an analyser which can be preset to trigger at a range of temperatures. It's made by Kidde Products - www.kfp.co.uk - and they brand it as Alarmline.

Bill.

[Guest G.J.M]

Just a passing thought, if a detection cable in a void that has no smoke detection is subject to a fire, the T&E will cause a fault to flag up on the panel long before the FP cable would, there are always two sides to everything......t&e cables in voids may in fact be safer then HR cables.......

tha fault tone from the panel is not going to evacuate the buidling and how many sites do you know that tend "not to hear the fault buzzer"?

The time that a fr cable had become totally useless then the fire would have alreday burned throught the void and smoke would be hitting the nearest afd.

unlike t+e where the nearest afd from the void would now no longer be working.