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Do you install fire alarm systems?

Chris Pearson
Bit of thread drift going on elsewhere, so I have started a new one.


"Do you install fire alarm systems?" - a question which is asked on insurance renewal, but what does it mean?


IMHO, there is a world of difference between providing a mains supply with third core for linking for a couple of smoke detectors and a heat detector in the kitchen on the one hand (i.e. the minimum grade D2 LD3); and a full on panel with separate detectors and sounder etc. (grade A LD2) in a large house. I consider myself perfectly capable of providing the former, but have never attempted the latter.


So where does the threshold lie? I'd be interested in views on certification too please.
  • 0
    Nikp:
    Sparkingchip:

    Domestic smoke and heat alarms have mains voltage throughout their circuit. 


    Testing domestic smoke and heat alarms should be carried out following the manufacturers instructions,   by pressing the test button. 


    The expiry date is on a label.


     


    I don’t really do much on domestic side, but don’t they normally have a shelf life of ten years, and if peeps really wanted to test surely buy a can of smoke. 




    That's my point - it's more than the test button. I have a few Montecristos from my visits to Gibraltar. Would they do?


  • 0
    No cans of smoke, no hot air guns, follow the manufacturers instructions and press the test button.


    They have an expiration date on them.


    Anyone who cannot understand how to check smoke and heat alarms are fit for purpose should not be a letting agent, landlord or electrician.
  • 0
    There you are Andy, you can do that, but it needs to be in the limitations box, "Only test buttons pressed". Real fire alarm system tests need smoke, heat, thermometers, etc to check full functionality.
  • Former Community Member
    0 Former Community Member
    davezawadi (David Stone):

    There you are Andy, you can do that, but it needs to be in the limitations box, "Only test buttons pressed". Real fire alarm system tests need smoke, heat, thermometers, etc to check full functionality.


    You can also use bubble wrap for real fire alarms, works a treat when testing high beam detection. 


  • 0
    davezawadi (David Stone):

    You posted as I did Andy, which regulations are there specifically for smoke alarms? Is the BS listed in the appendix?


    113.1 and  113.1.1


    Z.


  • 0



    The earth is so that the panel can flag a wire to earth fault if cabling insulation is mechanically damaged- a  positive to earth fault or a negative to earth fault means the cable has been spiked, but the rest of the self test to see the terminator resistor may still pass.


     


    As I see it the earth (C.P.C.) wire and "tin foil" are used with FP200 cable just because they are  integral to the cable. The fire alarm panel will detect a fault if a nail is driven through a cable even if it is not earthed, in these cases.


    1. Broken positive conductor.


    2. Broken negative conductor.


    3. Short between the two above.


    Earth NOT needed in all three cases.


    The cable only carries 24 Volts at a tiny current. And all components are made of plastic. Earth not needed.


    Perhaps the screen protects the cables from strong magnetic fields or radio interference. I am not really sure on that.


    Z.


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    My (admittedly vague) understanding of the foil in FP200 cable is that it's not for any shielding or earthing purpose, but as a vapour barrier to stop hot and possibly corrosive gases (perhaps oxygen??) initially attacking the inner layers.
  • 0
    wallywombat:

    My (admittedly vague) understanding of the foil in FP200 cable is that it's not for any shielding or earthing purpose, but as a vapour barrier to stop hot and possibly corrosive gases (perhaps oxygen??) initially attacking the inner layers.


    Yes, this stuff.

    https://www.bing.com/videos/search?q=youtube+FP200+cable&docid=608017582824820065&mid=6D3E9BC3C569513031576D3E9BC3C56951303157&view=detail&FORM=VIRE


    Z.


  • 0
    1. Broken positive conductor.


    2. Broken negative conductor.


    3. Short between the two above.


    Earth NOT needed in all three cases.

    What about a nail through two cables running together? Shorting one say +ve conductor to the same of another circuit will likely not trip/blow anything but will likely result in mis-operation. An earthed screen on the cables allows that to be detected (OK not necessarily earthed, but at some voltage distinct from that of the cores - but earth is probably handy for that).

       - Andy.
  • 0
    The CPC and screen must be earthed. The detail is in the BS5839 suite of documents, which you need if you are doing this work. 


    Regards,


    Alan.

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