Working with DD243

In this penultimate article on DD243 we tackle two of the most frequently asked questions at the training seminars. Generally, one of the greatest concerns candidates have who attended the SSAIB seminars is the methods used to unset the system.

  Just about 100 per cent of the systems population have a problem when it comes to this section of DD243!

So to reiterate the methods used and provide an explanation for those readers who missed earlier parts of this eries, here they are:

Means of unsetting
Unlocking the initial entry door unsets the whole or unsets part of the system facilitating the following:
a) In part set, entry to areas to be prevented by locks
b) Unlocking the doors to set areas unsets that part of the system
c) Status of locks to be monitored at the control panel and the
d) System will be prohibited to set until all relevant doors are locked

Unlocking the initial entry door disables all means of confirmation
If the entry timer expires it will be signalled to the ARC as an unconfirmed alarm. Any deviation from entry route will be signalled as an unconfirmed alarm.

When using this option there must be written confirmation to the customer informing them that all confirmation throughout the protected premises will be disabled during entry.

  The alarm company should also obtain written acceptance and confirmation from the customer of the disabling of the means of confirmation.

Opening the initial entry door disables all means of confirmation.
If the entry timer expires it will be signalled to the ARC as an unconfirmed alarm. Any deviation from entry route will be signalled as an unconfirmed alarm.

When using this option there must be written confirmation to the customer informing them that all confirmation throughout the protected premises will be disabled during entry.

The alarm company should also obtain written acceptance and confirmation from the customer of the disabling of the means of confirmation.

Just about 100 per cent of the alarm systems population have a problem when it comes to unsetting of the system under DD243!

nb: This method of unsetting is one which insurers do not consider secure.

Completion of Unsetting Using Portable ACE
Unsetting from outside the protected area is now permitted using a portable ACE (i.e. key fob).

If this method is used the entry door must still be fitted with an entry timer. Or opening the entry door starts the entry timer and then the system is unset using a token.

If an alarm occurs during entry or as a result of the expiry of entry time the alarm should be notified to the ARC as unconfirmed.

Using this method of unsetting a confirmed alarm can occur if two or more independent detectors located off the entry route are activated after expiry of the entry time... and finally

Unsetting is carried out in conjunction with the ARC
If this option is used then its needs to be in accordance with BS4737-1 1986, 5.3.2. providing the procedures ensure that a confirmed alarm is not generated, and/or that an alarm is not designated by the ARC as confirmed, unless there is a high probability of genuine intrusion or genuine attempted intrusion.

Filter tips
Q: How does the ARC handle alarm filtering?
A: The ARC should apply alarm filtering to all unconfirmed alarms. Having said this, alarm filtering need not be applied to an unconfirmed alarm that has been preceded by a transmission fault signal installed at the same premises and in the same set period. Also alarm filtering from an unconfirmed alarm does not have to continue if the ARC receives a transmission fault signal from the same premises during the same set period after the initial alarm signal has been received. If the cancellation of a signalled alarm condition is carried out it should be individually authorised by the customer with a defined alarm filtering routine. The user or the intruder alarm system should communicate with the ARC using coded words or numbers confirming that the intruder alarm system has mis-operated and the signalled alarm should be cancelled out.

In some circumstances alarms are allowed to be held in the filtering delay for more than 120 seconds

An unconfirmed alarm should have a delay of 120 seconds. BS5759 recommends that this is the maximum time for an alarm filtering delay before an alarm call is made. This delay allows the opportunity for the alarm signal to be designated as a false alert and cancelled.

During the alarm filtering period if the ARC receives a signal that is identified as (a) mis-operation or (b) that the intruder alarm is unset, the ARC (in the absence of any contrary indications, these being, audible or visual evidence of genuine intrusion or attempted intrusion), should designate the received signal condition as false alert and treat the alarm condition as cancelled.

  Where a sequentially confirmed alarm is received during the agreed filtering delay, the alarm call should be delayed until the end of the filtering period, providing the opportunity for the sequentially confirmed alarm to be signalled as false alert.

An exception to the delay period may be made where when the four following conditions are satisfied:
1) The ARC has agreed in advance with the client to provide monitoring of the set and un-set conditions in accordance with BS5759.
2) Sequentially confirmed alarms are received at least 30 minutes before the earliest time agreed for setting.
3) Sequentially confirmed alarms are received at least 30 minutes before the earliest time agreed for unsetting.
4) The ARC has separate evidence indicating that the intruder alarm at the protected premises is in the set condition and has been set for a period of not less that 15 minutes.

Alarm companies need to advise customers in writing that where a mis-operation signal or unset signal is received by the ARC, within the specified alarm filtering delay time, the ARC will normally cancel the alarm condition regarding it as false alert. When alarm monitoring is affected at the ARC the processing of alarms by the ARC may become delayed, this is allowed for in BS5759. Under these circumstances it is allowed for alarms to be held in the alarm filtering delay for longer than 120 seconds and for the alarm to be cancelled if a mis-operation signal or an un-set signal is received during extended alarm filtering delays.

Having said this, extension to alarm filtering delays should be kept to a minimum in compliance with BS 5979. There should also be an indication at the ARC available to the supervisor of the number of alarms held in the filtering delay to facilitate optimum use of operators and the contacting of staff in reserve.