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BS 8519

Hello,

I understand that the standard identifies the need for a dedicated containment for the fire rated life safety circuits. I assume this is so the normal circuits (non fire rated) will not compromise the integrity of the life safety circuits in case of fire (eg normal circuits will be on fire before the fire rated circuits which will be next to them if they were installed on the same containment).

But wouldn’t the same happen with the cpcs of the life safety circuits that are not fire rated?

Furthermore, is it ok to install on the same containment a circuit with 30 mins fire survival time (eg fire alarms) along with a circuit of 1 or 2h fire survival time (eg disabled refuge)?

I was under the impression that the fire survival time of a circuit is based on its wickest component but this does not always seem to be the case since the cpc are installed in the same containment.

It would be appreciated if you could share your thoughts.

Parents

0 Former Community Member over 4 years ago

Generally, the reason for separate containment is that all and sundry messing about with non safety systems aren't likely to damage life safety cabling - although correctly you do need to consider the interaction hazard between systems.

CPC's aren't specifically a worry per se - to melt the conductor needs temperatures way beyond the fire rating of the cable - and basically a bit of copper with all the sheathing burnt off, is still an effective CPC.

There is usually no issue with BS 5839 life safety systems of differing fire resistance sharing containment - but in your example, it should raise an eyebrow as to why the fire detection and alarm is only a 30 minute system, when the refuges are a 120 minute system - one would imagine a facility needing refuge comms would also need an enhanced grade on the Part 1 system to reflect the rating on the Part 9 system.

What you shouldn't do is mix non BS 5839 systems with other systems eg, it's not appropriate to run fire and emergency lighting on the same containment (as both relevant standards advise against it for the reasons given in my first comment

Regards

OMS
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0 Former Community Member over 4 years ago

Generally, the reason for separate containment is that all and sundry messing about with non safety systems aren't likely to damage life safety cabling - although correctly you do need to consider the interaction hazard between systems.

CPC's aren't specifically a worry per se - to melt the conductor needs temperatures way beyond the fire rating of the cable - and basically a bit of copper with all the sheathing burnt off, is still an effective CPC.

There is usually no issue with BS 5839 life safety systems of differing fire resistance sharing containment - but in your example, it should raise an eyebrow as to why the fire detection and alarm is only a 30 minute system, when the refuges are a 120 minute system - one would imagine a facility needing refuge comms would also need an enhanced grade on the Part 1 system to reflect the rating on the Part 9 system.

What you shouldn't do is mix non BS 5839 systems with other systems eg, it's not appropriate to run fire and emergency lighting on the same containment (as both relevant standards advise against it for the reasons given in my first comment

Regards

OMS
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BS 8519

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