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Conduit requirements and cable type

Former Community Member
Former Community Member

I’m in the process of installing seven hard wired fire alarms into our property all of which have to be interlinked.



I intend to re use a now empty steel conduit that runs from right beside our consumer unit up into the loft space. The steel conduit at its point of entry into the loft terminates there presumably the rest was removed in the past. I want to run a cable from there which will have to do an up and over brickwork in the loft.



My first question, is it acceptable in compliance with electrical regulations to simply clip the cable to the brick at the mortar joints or do I have to or even if strictly not necessary should I, put the cable in PVC conduit? This area is not trafficked.



Once I have crossed the brick work and come down to the first alarm, from there I intend to run a cable down the near center of the loft adjacent to the walkway in pvc conduit parallel to the 2 existing lighting circuit conduits located above the joists. I am not going to drill through the joists. At points along the conduit there will be junctions to allow clipped cable not in conduit to be ran parallel to the joists to the relevant alarm. The conduit is going to be a straight run, so my question is having consulted a few sources that state 1.5mm flexible cable not twin and earth must be used in conduit, does it? I understand the reason for flexible cable in conduit with a lot of turns and junctions but this is a straight run.


Thanks


Parents
  • 0
    Sounds like the real risk is cooking. Heat alarms rather than smokes are the way forward to avoid false alarms.

    Anything more than 2 or 3 flats, or more than one set of stairs  is the sort of situation to use red FP type cable, and a panel system (type A) either 4 core or 2 depending if sounders and sensors share wires or have separated loops.


    Are you sure that a type D is enough -  as if not,   you will need call points all possible fire exit doors as well ?

    please, and I'm not trying to be funny, before you start, do check exactly what you are supposed to be installing or you may end up doing it twice.

    (I do realise Scottish rules are not the same as English, but I think it is similar.)


    mike

    For reference.

     

    Grade A: Fire alarm system with detectors and a central control panel. Usually with call-points (break glass units) near exits and on each landing



    Grade D: System of (usually interlinked) mains-powered smoke or heat alarms with backup batteries. The interlink can be achieved with cable or radio-interlink. In low risk properties the mains power supply for smoke alarms might be replaced with a requirement for ten year sealed battery supply (usually combined with radio-interlink).



    Note: in the 2019 update to BS 5839-6, Grade D was split into D1 (tamper-proof backup battery) and D2 (user-replaceable backup battery).



    The coverage within the building by the detection system is described with the following codes:



    LD1: Covers all circulation spaces that form part of escape routes plus all rooms in which a fire could start








Reply
  • 0
    Sounds like the real risk is cooking. Heat alarms rather than smokes are the way forward to avoid false alarms.

    Anything more than 2 or 3 flats, or more than one set of stairs  is the sort of situation to use red FP type cable, and a panel system (type A) either 4 core or 2 depending if sounders and sensors share wires or have separated loops.


    Are you sure that a type D is enough -  as if not,   you will need call points all possible fire exit doors as well ?

    please, and I'm not trying to be funny, before you start, do check exactly what you are supposed to be installing or you may end up doing it twice.

    (I do realise Scottish rules are not the same as English, but I think it is similar.)


    mike

    For reference.

     

    Grade A: Fire alarm system with detectors and a central control panel. Usually with call-points (break glass units) near exits and on each landing



    Grade D: System of (usually interlinked) mains-powered smoke or heat alarms with backup batteries. The interlink can be achieved with cable or radio-interlink. In low risk properties the mains power supply for smoke alarms might be replaced with a requirement for ten year sealed battery supply (usually combined with radio-interlink).



    Note: in the 2019 update to BS 5839-6, Grade D was split into D1 (tamper-proof backup battery) and D2 (user-replaceable backup battery).



    The coverage within the building by the detection system is described with the following codes:



    LD1: Covers all circulation spaces that form part of escape routes plus all rooms in which a fire could start








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