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Fire alarm cabling


Guest RedMeerkat

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Guest RedMeerkat

Am I correct in thinking that cabling for a fire alarm should still be routed separately from that for all other services?  A client has had the cabling all installed (for aesthetic reasons I am sure!) in open cable trays with all services together and what looks like plastic cable ties clipping them in.  This isn't mentioned anywhere on the commissioning certificate as a departure from BS5839-1 (I'm not sure if that's even allowed any more!).  I'm doing the FRA and this doesn't look normal to me (though it's very pretty and must have been a nightmare for the installing electricians...).  Picture below shows a vertical cable tray open to the rest of the premises.

image.png

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It's not secured by metal clips within manufacturer's instructions (almost always 300mm/400mm depending if wall or ceiling) so that's the first major non conformity which will affect both the integrity of the system and the safety of firefighters and others

"Methods of cable support should be non-combustible and such that circuit integrity is not reduced below that afforded by the cable used, and should withstand a similar temperature and duration to that of the cable, while maintaining adequate support.
NOTE 10 In effect, this recommendation precludes the use of plastic cable clips, cable ties or trunking, where these products are the means of cable support.
NOTE 11 Experience has shown that collapse of cables, supported only by plastic cable trunking, can create a serious hazard for firefighters, who could become entangled in the cables."

As for sharing with other cables:
"To avoid the risk of mechanical damage to fire alarm cables, they should not be installed within the same conduit as the cables of other services. Where fire alarm cables share common trunking, a compartment of the trunking, separated from other compartments by a strong, rigid and continuous partition, should be reserved solely for fire alarm cables.
To avoid electromagnetic interference with fire alarm signals, any recommendations by the manufacturer of the fire alarm equipment in respect of separation of fire alarm cables from the cables of other services should be followed."

Is the cable printed with manufacture/product info - it looks a bit thin for FR cabling (its probably just the photo making it look so, but it wouldn't be the first system sneakily cabled in non-FR red PVC cable!)

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Guest RedMeerkat

Thanks Anthony, that pretty much confirms what I thought.  I didn't see anything printed on the cables.  I will certainly be following this up with the client so they can investigate with their installer.  Not impressed so far with the documentation I've been given so far for the alleged specification and installation.  The commissioning certificate doesn't even give the category of the installation (I think it's L1 but it's impossible to be certain!)

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  • 3 weeks later...
Guest RedMeerkat

Just because I like a story to have an ending (even though it's not quite the final ending yet)

The installer has now returned and fitted metal clips.  The cabling is all the correct grade.  We are still discussing whether cabling in a cable tray has to be physically separated - to be continued I suspect!

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