The changing world of burglar alarms

In 2001 the ACPO POLICY was introduced as a permanent set of rules that have to be followed if a police response is needed for your burglar alarm system.áá

On 1st July 2002 an additional set of rules, DD243:2002, was adopted, which radically changed the way that burglar alarm systems must operate in order to satisfy the police.

áThese rules apply only to systems that are monitored and have police response when an activation occurs.á They do not apply retrospectively to systems installed before the policy or directive were formally adopted, but will be enforced, if police response is withdrawn on such a system, before that response can be reinstated.

DD 243 : 2002 & the Installer

Some police forces around the country gave a period of grace before starting to implement this new regulation but this is now at an end. This means that all new or reinstated communication systems that require a police URN in England, Wales and Northern Ireland will need to conform to DD243 : 2002. The aim of this amended policy is to reduce the number of false alarms from security systems that the police attend.

The official DD243 : 2002 document is available from the British Standards Institute.

The main areas that have been changed apply to the way that alarm conformation signals (Alarm B) are handled with specific changes to alarm conformation signals during entry to the protected premises once the entry time has been started.

Below are the key points of the DD243 policy. This is not a definitive list and should not be seen as the limit of an installation company's responsibilities, this is just a guide to some of the main issues.


Section 4 Primary design and configuration considerations:

4.1 Design Objectives
4.3 Transmission Fault Signals

Section 5 Design, installation and configuration of intruder alarm systems:

5.4.1 Criteria for sequentially confirmed alarm conditions
5.4.2 Configuration of movement detectors that may offer a sequentially confirmed alarm
5.4.3 Configurations not regarded as offering a sequentially confirmed alarm condition

Section 6 Other means of minimizing false alarms:

6.2 Alarm Filtering
6.3 Means of Completion of setting
6.4 Means of unsetting

Section 4 Primary design and configuration considerations

4.1 Design Objectives
IASs (Intruder Alarm Systems) should be designed, installed and configured:
a) á áto provide effective confirmation facility; and
b) á áto minimise the likelihood of false alarms.

Emphasis is placed on the design of the system for compliance with the policy requirements. This requires proper risk assessment including detailed discussion with the client and taking into account the insurance requirements.

4.3 Transmission Fault Signals
DD243 recognises that there are two circumstances where there may be high confidence that there is a genuine intrusion or attempted intrusion.
a) á áif 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;
b) á áif an ARC receives two transmission fault signals from the same protected premises, one from each of two transmission paths of different technologies (e.g. cable and radio)

The ARC and the police will treat either of the above circumstances in the same way as confirmed alarm messages.

The Provision of two transmission paths is optional - and the provision of two transmission paths does not equate, of itself, to the system being fitted with confirmation technology.

Section 5 Design, installation and configuration of intruder alarm systems incorporating alarm confirmation technology

5.4.1 Criteria for sequentially confirmed alarm conditions
The general criteria for the way an IAS is configured for an alarm condition to be sequentially confirmed is as follows:

a) á áAt least two separate alarm conditions are reported, each originating from an independent detector, within the confirmation time; and
b) á áThe two detectors must be:
EITHER of different technologies

OR (if they are of the same technology) the two detectors must not have overlapping areas of coverage.

The detectors must have separate outputs and be connected to separate zones in the control panel. Although two separate zones must be used, the detectors can be in the same area, or room.

The 'confirmation time' is the term used for the period of time after the first activation, during which a second, or confirmed, activation can be reported. The confirmation time must not be less than 30 minutes and must not be more than 60 minutes.

Two detectors of different technologies are allowed. Two detectors of the same technology are also allowed provided that those detectors do not have overlapping areas of coverage.

Where both detectors are movement detectors further rules apply under the following section:

5.4.2 Configuration of movement detectors that may offer a sequentially confirmed alarm In simple terms, the key points from this section are as follows;

Where any two movement sensors are used (single technology or dual technology) and they do not have overlapping areas of coverage, they should be located far enough apart to minimise the possibility of false alarms. (NSI suggests 2.5m)

In the case of two movement detectors, with any overlapping areas of coverage, at least one must be a dual-technology detector. The overlapping areas of coverage should be at the far end of the field of view, to minimise the overlapping coverage areas and thus, the likelihood of false alarms. Again these detectors should be mounted 'some distance apart'.

Two separate dual-technology movement detectors with overlapping areas of coverage are allowed, providing the above criteria is met.

5.4.3 Configurations not regarded as offering a sequentially confirmed alarm condition This section describes other configurations that are not acceptable under the DD243 policy.

These are basically as follows:

A 'double knock' configuration
A 'dual-technology' detector
Two (or more) detectors or devises of the same type with overlapping areas of coverage including: -

Two vibration sensors
Two glass break sensors
Two foil-on-glass detectors
Two door contacts (or similar)
Two audio monitoring devices
Two video motion detection devices
Two or more detectors responding to changes in atmospheric pressure

Section 6 Other means of minimizing false alarms

6.2 Alarm Filtering
All IASs must EITHER:

a) á áhave the means to indicate to the ARC whether the IAS is set or unset;
á á á áOR
B) á ábe capable of generating a secondary signal identifiable at the ARC as a mis-operation signal.

These requirements remain the same as under the NACP 14 and the previous DD243: 1999 document.

The filtering period (maximum 120 seconds as recommended in BS5979) will apply from the first, unconfirmed activation and will continue to run even in the event of a second, confirmed activation during the filtering period.

There are a series of conditions that mean that alarm filtering can be over-ridden. All four must apply and these would only ever be effectively possible on some commercial systems. The four conditions are:

1) á áSet/Unset monitoring in use
2) á áAlarm at least 30 minutes after latest agreed setting time á á
3) á áAlarm at least 30 minutes before earliest agreed unsetting time
4) á áSystem set at least 15 minutes before alarm occurs

6.3 Means of Completion of setting

The six permitted options for completion of setting IASs are as follows:

a) á áKey operated shunt lock fitted to final exit door
B) á áPush button switch mounted outside the protected premises
c) á áProtective switch (ie door contact) fitted to the final exit door
d) á áPortable ACE
e) á áIn conjunction with an ARC
f) á áIn the case of systems installed to comply with BS EN 50131, other means.

The traditional timed exit method of setting is now not allowed under DD243 unless the set period is completed by the means of a push-to-set button or final door set using door contacts.

Other methods are now acceptable including completion of setting using portable ACE (ancillary control equipment).

It is worth noting that means of COMPLETION of setting is not the same as means of setting. For example a traditional end user code entered into a Remote Keypad is acceptable, provided the completion of the setting procedure is by a push-to-set button or by door contacts on the final exit door.

Where systems are installed to EN 50131, setting from outside the protected premises is permitted.

Whatever method is chosen, there should be a time-limited indication to the user that the setting has been completed. This may be audible i.e. the cessation of the exit tone.

6.4 Means of unsetting
There are five options for means of unsetting under the DD243 policy.

a) á áUnlocking the initial entry door unsets the IAS
B) á áUnlocking the initial entry door disables all means of confirmation
c) á áOpening the initial entry door disables all means of confirmation
d) á áCompletion of unsetting is achieved using portable ACE
e) á áUnsetting is carried out in conjunction with an ARC

This section is possibly the one that will have the biggest impact on many installation companies.

The traditional timed entry route, with the end user entering their code at a remote keypad, is no longer acceptable.

Options (a) and (b) require an electrical connection between the lock and the IAS. For example an electric lock or a shunt lock may be used. Electronic access control liked to the IAS is also acceptable.

Option (c) is obviously the one that leaves greatest risk as a forced entry through the entry door would disable confirmation! It is unlikely that this method of unsetting will be acceptable to insurers for all risks. Furthermore, if this method is adopted the installation company must advise the customer in writing that all confirmation is disabled when the entry door is opened. They must also obtain, from the customer, in writing; that this is acceptable.

Option (d) will allow the use of an entry timer in conjunction with portable ACE. The portable ACE can be self-powered or can be in the form of a proximity tag or card. It must be a single action device to unset the system (such as presenting a tag or card to a proximity reader) and must offer security of no less than that provided by a key switch of 1,000,000 differs.

Where a portable ACE is used however, there are points worth noting with regard to confirmed alarms involving the entry route.

If the entry time expires without the IAS being unset, an unconfirmed alarm will be signalled to the ARC. At that point the ARC will apply the alarm filtering delay.

If a detector off the entry route subsequently activates a further unconfirmed alarm will be signalled to the ARC. Only on activation of a second, independent detector will a confirmed alarm signal be able to be sent to the ARC.

Where detectors off the entry route activate during the entry time, it is considered likely to be due to user error and these will not signal an alarm to ARC, but would cause a local alarm.

Questions & Answers

Q. I have many older systems installed will they comply.
A. Existing systems are exempt. Only new systems or systems that are being reinstated after response has been withdrawn are affected.

Q. What is a confirmed alarm
A. A confirmed alarm is an alarm that has been generated from two independent detectors that are not on an entry or access route within 30 to 60 minutes.

Q. DD243 states that unconfirmed alarms should start a 30 to 60 minute time window.
A. New DD243 Compliant Alarm control panels allow you to program a Confirm Window Time within the stated perimeter.

Q. I've heard that I am not allowed to send confirmed alarms if the entry timer has been started, is this true.
A. No. On a standard type of system you are not allowed to send confirmed alarms once the entry timer has been started. You are however able to use ACE and still send confirmed alarms for non entry/access type zones. ACE simplifies the unsetting procedure for the system and reduces the possibility of false alarms through user error.

Q. What is an unconfirmed alarm.
A. An alarm from any single detector or from two detectors of the same technology that have an overlapping area.

Q. How does an unconfirmed alarm become confirmed.
A. By a second independent detector not on an entry or access route being triggered.

Q. Am I allowed to use door locks with integrated switches.
A. Yes. But confirmation will be disabled if the door is unlocked when entering the premises. If however the door is forced (therefore not operating the switch) alarm conformation will remain active.

Q. If I use more than one detector in a room are they allowed to have overlapping areas of detection.
A. You may use for example two PIRs in the same room but the detection areas are not allowed to overlap. If you are likely to have overlapping areas of detection then it would be permissible to use one PIR and one Dual Technology Detector.

Q. I am concerned about a key holder attending an unconfirmed alarm may not be aware that on his way to the premises the alarm has now become confirmed as this may be a Health & Safety Issue.
A. Setting the bell as unconfirmed will indicate the unconfirmed alarm and setting the strobe as confirmed will show the key holder that the alarm has now been confirmed before he enters the premises. Another alternative would be to connect an output programmed for Status to an indicator (i.e LED) that can been seen from outside

WARNING - Take care that your burglar alarm quotation includes all of the new measures.

Of course, we understand and implement all of the above rules. Trust us to do the job properly.

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