Part 2 of Security Insatller's close-up look at DD243:2002 and the demand for confirmed alarms ... This month: your questions anwered
DD243:2002 has now been implemented for the past two months. Over the past few weeks I have received a number of phone calls and e-mails from companies with regard to particular difficulties they are having with the interpretation and technicalities of the document. The majority of the calls have been from installers and surveyors who have not had access to training or been able to attend one of the many seminars around the United Kingdom which the SSAIB has conducted since March.

The SSAIB training courses have been very well attended and successful in providing help and support in the interpretation of DD243. As a result further courses have been requested by SSAIB members and several more are planned for the next few months.

From the training seminars that have been conducted on DD243 a number of questions that have been raised will, I'm sure, benefit others in the industry who survey, install and maintain systems. Here are some of those questions.

Do all confirmed alarm systems require dual path signalling?
No. Having said this, confirmation does extend to signalling if you install dual path transmission. DD243 recognises that there are two circumstances where there may be high confidence that there is genuine intrusion or genuine attempted intrusion ...

  • If an ARC receives a transmission fault signal followed by an alarm signal, or vice versa, from the same protected premises during the same set period.

  • If an ARC receives two transmission fault signals from the same protected premises, one from each of the two transmission paths of different technologies (e.g. cable and radio).

    A couple of points on this: 1) The provision of two transmission paths is optional and requires agreement with the customer.

    2) The connection of two transmission paths do not equate to, or constitute, equipping the alarm system with alarm confirmation technology.

    The SSAIB courses have been very successful and well attended ... as a result several more are planned over the next few months

    Can an alarm system be set using a portable device?
    Yes it can. DD243 states the setting methods which must be used are:

    • Means of completion setting the system
    • Key operated shunt lock on the final exit door
    • Push button switch outside the protected premises
    • Door contact on the final exit door of alarmed premises or area
    • Set in conjunction with the ARC
    • Portable ACE (ancillary control equipment)
    • In the case of intruder alarms systems installed to comply with BSEN 50131, other means may be used.

    If a door contact is used as the means of completion of setting, then the control indicating or ancillary control equipment should be sited near to the final exit door. This is to ensure that unsetting can be achieved promptly and, in the case of intruder alarm systems, configured to generate a secondary signal identifiable at the ARC as a mis-operation.

    Also, where the setting procedure has been satisfactorily completed, there should be an indication that the intruder alarm system is set, except for intruder alarm systems installed to grade 1 and 2 of BS EN50131 1:1997 where indication of set is optional. The set indication should be time limited and should be indicated to the user at the time the intruder alarm system is set.

    Consideration must also be given to providing extra internal audible indications prior to setting (so that people within a building know that the intruder alarm system is due to be set, and to providing additional ancillary control equipment (so that if the intruder alarm system is set there are means available locally within the protected premises to unset the intruder alarm system).

    Does DD243 allow reinstatement of intruder detectors after an unconfirmed activation?
    DD 243 identifies three issues concerning this area:
    1. Intruder alarm systems incorporating sequential confirmation technology only.

    After the intruder alarm system has been set, if one detector not on the entry route activates, an unconfirmed alarm should occur and the confirmation time should start. If a second detector does not activate within the confirmation time and the confirmation time expires the intruder alarm system should be reinstated so that, again, if one detector activates, an unconfirmed alarm occurs and the confirmation time starts. If the system is unset before expiry of the confirmation time, then reinstatement does not need to occur.

    At the time of reinstatement of the intruder alarm system, an alarm condition should not occur. To achieve this the relevant detector(s) should be isolated and a signal sent from the control indicating equipment to the ARC to indicate that the detector(s) are isolated. At this point actions to be taken by the ARC upon receipt of a signal indicating that a detector has been isolated should be agreed with the customer and the ARC.

    If there is written agreement from the customer, the ARC may isolate faulty-activating detectors

    Systems using the initial entry door for unsetting: if the initial entry door is isolated due to being open circuit at the time of reinstatement of the intruder alarm, the intruder alarm system should be configured so that notification of any alarm and initiation of the confirmation time is delayed until the overall entry time expires. If an alarm occurs as a result of the expiry of the overall entry time, the alarm system should be notified as unconfirmed.

    The process of reinstatement should not remove an alarm condition. When the intruder alarm system is unset there should be an indication at the control indicating equipment that an alarm condition has occurred and a reset required.

    If the first detector to activate during the set period activates again within the confirmation time, it is allowed to re-start the confirmation time at the time of the second activation of the first detector. It is allowed to repeat this for further activations of the first detector, provided this is agreeable by all parties. This may be possible using extended format reporting. Each activation of the first detector should cause an unconfirmed alarm to occur.

    2. Intruder alarm systems incorporating audio and/or visual confirmation technology.

    Alarm signals received by the ARC should be unconfirmed alarms until otherwise designated by the ARC as audibly or visually confirmed. If the unconfirmed alarm is not designated as confirmed, the intruder alarm system should still be able to notify further unconfirmed alarm conditions to the ARC from detectors that have activated as well as from detectors that have not activated. If there is written agreement from the customer the ARC may also isolate detectors which activate repetitively e.g. due to a fault.

    3. Intruder alarm systems incorporating sequential confirmation technology and either audio and/or visual confirmation technology.

    If an ARC interprets an unconfirmed alarm (using either audio or visual information) and does not designate the unconfirmed alarm as audibly confirmed, the ARC operator may reinstate the intruder alarm system before the expiry of the confirmation time provided the technology permits and there is written agreement for this from the customer.

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    Security Installer