As we have ''Security'' brothers within our group company this is always cropping up. This is from one we prepared earlier:SHARED FIRE AND SECURITY SIGNALLING
VARITIONS TO BRITISH STANDARD BS5839 Part 1:2002
............... has a reputation of providing the highest standards of quality and service in the industry. In order to maintain these standards, we wish to draw to your attention the implications of transmitting fire and security signals on a common communication path.
The prime motivation for combining both fire and security signalling is cost saving. This is achieved by sharing one transmitter and one telephone line, therefore reducing installation costs and recurring rental charges. It is often the case that the communicator is incorporated into an existing security system and that the national security standards require the transmitting device to be contained within the security system tamperproof housing. It is at this point where the fire and security standards differ; the fire standards being much more onerous.
The fire standard generally referred to is BS5839 Part1:2002 “Fire detection and fire alarm systems for buildings – Part 1: Code of practice for systems design, installation, commissioning and maintenance”. The fire alarm system must remain operational and be capable of signalling a fire signal (and fault signal) 24 hours a day 365 days a year, therefore, BS5839 lays down stringent requirements for the power supplies, wiring, monitoring and protection of signalling paths and equipment. In summation the security system will not generally comply with the standard and will have one or more of the following variations:
1. No fire rated and mechanically protected interconnecting cables (power and signalling).
2. Signalling cable path not run through areas of low fire risk.
3. Signalling path not protected by automatic detection / extinguishing.
4. No open and short circuit monitoring of the interconnecting cables.
5. No appropriate and correctly labelled 240V ac power supply and isolator.
6. No minimum of 24 hour battery standby in the event of a 240V ac mains supply failure.
7. No remote indication of a 240V ac mains supply fault to the fire panel.
8. No remote indication of a communication path failure to the fire panel.
9. Security panel does not comply with requirements of BS5839 Part 1 2002 (EN54 -2 & 4)
Apart from the differences in standards there may also be operational difficulties when combining fire and security signalling, in particular, when two separate maintenance contractors are involved. Should a “fault” occur with the communications it may not be obvious as to which maintenance contractor to call out. A security engineer might disconnect the communicator whilst working on the security system without informing the appointed fire “responsible person” who would not then know that the fire signalling capability was inoperable. It is also often the case that the security engineer is not able to test the fire alarm system in order to prove that element of the security communicator nor has the fire engineer access to the security communicator due to it being in a tamperproof housing.
The cost savings made by combining fire and security signalling need to be considered against the reduced integrity of the fire signalling path. If the fire brigade link is an insurance requirement then your insurers should be consulted for their approval. Similarly if the attendance of the fire brigade forms an integral part of your evacuation plan then the method of signalling should be considered in this light.
It should be noted, however, that the British Standard is all embracing and often there is a requirement to vary from it for a given application. A major requirement of the British Standard is that these variations are discussed amongst all interested parties, agreed and then documented for inclusion in the certification record. If the signalling equipment is being installed by a third party then the above variations to the standards should be discussed, agreed and documented with all concerned.
(To enable you to consider fully all aspects of combined communications we will supply on request a copy of the relevant sections of BS 5839 Part1:2002).
We stopped at this point because we are in danger of allowing non techies to drift off. From an insurance point of view when you have shared signalling, the fire engineer will put the system on 999 with the central station during his service visits. They will by default ignore all signals from the premises during this period. Hopefully nobody will need to press the panic alarms for an armed raid.................. All to save a few pennies.
There was an incident ( not one of ours) in the south (Portsmouth area I think) When shared signalling failed leading to significant loss. It was well reported with costs flying around in all directions from the man in the wig. I do not have a copy now. I can try to get one if anybody is interested.
Sorry for delay and I hope we answered the original question and raised awareness !!!
Dave
