Burglar Alarm - Front Door Sensor

Discussion in 'Electricians' Talk' started by Alan Sausse, Aug 11, 2017.

  1. Rulland

    Rulland Well-Known Member

    Three wires on a biscuit, knowing where they go to the two wires for the zone.
  2. Alan Sausse

    Alan Sausse New Member

    Closer inspection - at least one of the reed switches is damaged (ie the glass housing is cracked). Seems to be permanently open, whether there's a magnet around it or not.

    Have contacted the alarm company to see if they have any of these sensors available. Also to ask their advice about the ID biscuit. It's already wired up to the sensor so I'm hoping they can send a replacement sensor and I'll just attached the ID biscuit to the same terminals on the new sensor. If they have any sensors in stock, that is...

    If they don't, I may try to replace the tiny reed switches myself - quick soldering job. Can I assume that the switches I need will be of the "normally closed" variety?
  3. Rulland

    Rulland Well-Known Member

    Yep, normally closed.
  4. Dr Bodgit

    Dr Bodgit Well-Known Member

    You should be able to wire the ID biscuit to a new reed switch.
  5. JP.

    JP. Screwfix Select

    Whats an ID Biscuit?
  6. Dr Bodgit

    Dr Bodgit Well-Known Member

    Small chip that attaches to the sensor and gives it an ID for the main controller to identify it by. It's the small white thing with 3 wires in it in the photo above
  7. JP.

    JP. Screwfix Select

    Thanks Doctor Bodge - must admit know next to zero about alarm systems, but at least I know what that biscuit is now.
  8. Pollowick

    Pollowick Well-Known Member

    It allows a single continuous cable run of up to 100m, uses just four cores and you have up to 30 biscuits on each.
  9. JP.

    JP. Screwfix Select

    Thanks Mr P, sounds like theirs a lot involved in alarm systems. Must admit there not my thing but if you are a good pukka installer of alarms then I would think theirs good money in fitting them.
  10. Rulland

    Rulland Well-Known Member

    Not any more!, to many companies touting, and most of them not doing a good job, unfortunately the client finds out to late, and that's when the likes of me has to step in to sort out the cack

    ID systems were great, a data bus, up to 60 devices, on a four wire line, but can be very prone to interference, if not installed carefully, nowt great at 3am call out when every device has gone into tamper due to 'external influence' lol.

    Imho ID is being swapped out as and when systems fail.
    Last edited: Aug 13, 2017

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