Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 44 replies
  • Subscribers 32 subscribers
  • Views 3784 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

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.
Parents
  • 0
    The actual electrics of the modern panel alarm is pretty trivial. Either there are 4 wires to the panel per zone (sounders and detectors 2 wires each) or two wires (sounders reverse polarity on the same pair as the sensors - so red may be negative?). The end may need termination resistor(s).

    More complex ones are still 2 wires to each point, but have a unique address per sensor so the reporting can be selective - fire in flat six kitchen is more help than fire in one of a dozen rooms.


    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.


    For installation, knowing if the sensors are the right type, and properly located is a different matter. When is a rate of rise thermal sensor preferred to an absolute temperature one etc... Do you need one in the cieling cavity etc etc.

    Then there is knowing about the correct sort of joint box, and all the attendant stuff. It is not totally trivial.

    The system in something like a block of flats should be looked at once a year by someone who understands all this, but often that may well not include sensor test in individual flats or operating all call points, it may not be practical to get to those on the wrong side of locked front doors.

    M.
Reply
  • 0
    The actual electrics of the modern panel alarm is pretty trivial. Either there are 4 wires to the panel per zone (sounders and detectors 2 wires each) or two wires (sounders reverse polarity on the same pair as the sensors - so red may be negative?). The end may need termination resistor(s).

    More complex ones are still 2 wires to each point, but have a unique address per sensor so the reporting can be selective - fire in flat six kitchen is more help than fire in one of a dozen rooms.


    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.


    For installation, knowing if the sensors are the right type, and properly located is a different matter. When is a rate of rise thermal sensor preferred to an absolute temperature one etc... Do you need one in the cieling cavity etc etc.

    Then there is knowing about the correct sort of joint box, and all the attendant stuff. It is not totally trivial.

    The system in something like a block of flats should be looked at once a year by someone who understands all this, but often that may well not include sensor test in individual flats or operating all call points, it may not be practical to get to those on the wrong side of locked front doors.

    M.
Children
No Data

Community Rules & Guidelines