Strathand Fire & Security

System Monitoring

Image 1

DD243: Doing It Right!!

All new monitored alarm systems that require a Police response must use a method of alarm confirmation.   Alarm confirmation methods are used to reduce the possibility of false alarms and thus reduce the time wasted by the Police in attending systems which have false alarm activations.
The British Standard DD243 details what methods of confirmation may be used and how the system must be configured.   In particular it details how a system may be armed and disarmed in order to reduce the likelihood of false activation by the system user.   It applies to monitored systems installed throughout England, Wales, Northern Ireland and Scotland and is a requirement of both ACPO and ACPOS security systems policy.
The standard was originally published in January 2002 and became effective in July 2002.   A revised version was released with some minor changes in December 2004.
Under DD243 there are 3 methods of alarm confirmation which may be used:
  • Sequential
  • Video
  • Audio
In addition to the above methods, confirmation of an alarm activation also extends to the alarm signaling system where dual path transmission is installed.   If any of the following incidents occurs an alarm is deemed to be confirmed and the Police called:
  • Alarm signal transmission followed by a transmission path cut*
  • A signal transmission path cut followed by an alarm signal transmission
  • Cuts on both signal transmission paths
*Note: Single path signaling systems can only provide line cut alarm confirmation in the event of incident 1 occurring.   Strathand recommends for high risk premises dual path signaling should be installed.
Sequentially Confirmed Activation
This requires two independent detectors to activate within a 30 minute timeframe.   The 30 minute timeframe will be programmed at the control unit.   For installation of movement detectors providing sequential confirmation the following applies:
  • Different technologies (may overlap)
  • Same technologies (may not overlap) except Dual Technology Detectors
  • Other detectors must not be triggered by the same “event”, for example 2 door contacts installed on same door.
  • Examples of permitted overlapping configurations:
    Passive and dual technology detectors
  • 2 dual technology detectors
 Examples of sequential configuration:
  • 1 movement detector (as above) and
  • vibration detector
  • breaking glass detector
  • foil-on-glass detector
  • door contacts
An alarm condition from the first detector should generate an unconfirmed activation.   If there is a subsequent alarm within the confirmation time then an unambiguous sequentially confirmed activation should be signaled.   If a separate detector does not activate within the confirmation time the system should reinstate automatically. 
 Following the activation of the first detector, if a second (confirmed) detector does not activate within the confirmation period the following applies:
  • Reinstatement of the first detector if possible
  • If not isolate and signal isolation to the ARC
  • If it is a perimeter detector the ARC must initiate key holder action (This needs to be agreed with the ARC)
  • If the entry door is isolated alternative means to initiate entry must be provided. An example of this could be a PIR.
Video confirmation system requirements
 Video equipment may be triggered by:
  • Intruder Detector
  • Video Motion Detectors (VMD)
 Here certain rules apply:
  • Video coverage must match the detection coverage
  • Video confirmation cannot commence until an alarm has been signaled to the ARC.
Site identification must be provided by remote equipment before viewing begins.   When ID is achieved the following will apply:
  • Minimum of 3 images following activation
  • 1 image at time of activation
  • 2 images after activation (within 5 (s))
 It should only be possible to view the site after an activation has occurred. 
Audio confirmation systems requirements
 For audio confirmation systems the audio equipment may be triggered by an:
  • Intruder Detector
  • Audio listing device (ALD)
  If one of these methods is employed certain rules apply:
  • Audio coverage must match the detection coverage
  • Audio confirmation cannot commence until an alarm has been signaled to the ARC
 When an alarm is received at the ARC the listening periods, as a minimum, are:
  • 60 (s) for intruder detection
  • 30 (s) for audio detection
 For audio confirmation of intruder detection:
  • at least 10(s) stored audio before an activation
  • at least 15 (s) stored audio after an activation
 For audio confirmation of audio detection:
  • at least 1 (s) stored audio before activation
  • at least 15 (s) stored audio after activation 
 Audio and Video systems must also provide sequential confirmation.  
Disclaimer This information is given as a general guide only.  It is not intended to contain definitive legal advice.  Professional legal advice should be sought as appropriate in relation to a particular matter.