BURGLAR ALARM BASICS AND INSURANCE

Presented by Duncan Waugh

Alarm Warranty Alarm Warranties on a policy

generally require that the burglar alarm is :

A) Properly maintained B) Armed (on) when the premises are

unoccupied. The term ‘activated’ is in respect of

the alarm being triggered during illegal intrusion.

On this basis, the Insured is given the benefit of a premium discount.

TAKING OUT THE CONFUSION

BASIC COMPONENTS The Brain

Control Panel The Nervous System

Magnetic switchesGlass break detectors

The “EYES”Passive Infra Red Detectors (PIRD’s)

The MouthRadio transmitter or tele-communicator

The Brain – Post Loss

Nervous System – Magnetic Switches

Perimeter device

Magnetic switches need their magnets…

Door contacts / magnetic switches

Magnetic alarm switches are connected in a loop, which are always closed (always in contact). They consist of electric contact switches and magnets. When a door or window is closed, the switches sensitive to magnets close the circuit and when they open, breaks the contact thus cutting the circuit. This sets off the alarm. End of line resistors are necessary to prevent effective tampering.

Glass break detectorPerimeter device

The original method used to protect glass required the application of a conductive metallic tape (foil), directly to the glass. The foil was varnished onto the glass 4-5 centimetres from the edge and glued around the perimeter of the glass. If the glass was broken, the cracks would cause the foil to break. While this was apparently a reliable method of detecting glass breakage, it was very labour intensive to install and prone to extensive service repairs from scratches and breaks in the foil.

Today almost all glass break sensors are acoustic devices, although vibration detectors are still being used. There are many advantages to using acoustic detectors. They are visually attractive, less expensive to install and maintain. It is said that current detectors are very good at tripping to only the sound of breaking glass and that ‘new’ glass break units are less prone to false alarms.

The ‘eyes’ – Passive Infra Red

The most misunderstood alarm device

Is a Passive Infra Red

Detector a motion sensor , or is it a heat

detector?

The ‘eye’ is simply a pyro-electric sensor

A Passive InfraRed sensor / detector (PIR sensor / detector) is an electronic device that measures infrared (IR) light radiating from objects in its field of view. PIR sensors are often used in the construction of PIR-based heat detectors, often confused for motion detectors. Apparent motion is detected when an infrared source with one temperature, such as a human, passes in front of an infrared source with another temperature, such as a wall.  

All objects emit what is known as black body radiation. It is usually infrared radiation that is invisible to the human eye but can be detected by electronic devices designed for such a purpose. The term passive in this instance means that the PIR device does not emit an infrared beam but merely passively accepts incoming infrared radiation. “Infra” meaning below our ability to detect it visually, and “Red” because this colour represents the lowest energy level that our eyes can sense before it becomes invisible.  Thus, infrared means below the energy level of the colour red, and applies to many sources of invisible energy. 

Infrared (IR) light is electromagnetic radiation with a wavelength between 0.7 and 300 micrometres, which equates to a frequency range between approximately 1 and 430 THz.

IR wavelengths are longer than that of visible light, but shorter than that of terahertz radiation microwaves. Bright sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level. Of this energy, 527 watts is infrared radiation, 445 watts is visible light, and 32 watts is ultraviolet radiation. Therefore, bright sunlight, being the main source of infrared light, effectively and literally ‘blinds’ external passive infrared detectors, as well as internal detectors that face into strong sunlight shining through windows.

It is no more a motion sensor than torch is an X-ray device. It gives the impression it is a motion sensor because it more often than not activates when there is apparent motion.

Except when the item moving is at the same temperature as the room, or, the heat of the room exceeds the operating temperature of the device.

The Insured could not understand why the alarm did not activate …?

Nor could this one….?

INSTALLATIONS

South African Intruder Detection Services

AssociationSAIDSA

By-law 5 and 25: Location and enclosure Where ceiling access is possible, the control

panel, radio and antenna shall be installed a minimum of 1.5m below the ceiling, in an area protected by a volumetric detector on an instant zone not visible from outside. The door of the control panel must be tamper proofed on a 24 hour zone. (July 2003)

January 2011

The control panel should not be installed near devices that may give off and electromagnetic field, or near the ceiling.

Why not install PIRD’s in the roof cavity?

A PIRD is a heat sensor……

On the installation instruction insert, the maximum operating temperature is listed, usually between 40°C to 50°C. The human body is measured at 37.98°C. The PIRD cannot detect something that is colder than itself.

What is the average temperature inside a roof cavity of a house in Durban in December?

Can a PIRD see through roof trusses?

Most PIRD’s cannot operate in a roof cavity, it is too hot.

External Active Infra Red

Active infrared is when infrared light is emitted and then detected when it bounces back off a surface. Passive infrared is the infrared given off naturally from the surface of a material.

The difference….

The Power Source

The battery is the single most important component of the burglar alarm system. The system is totally dependent on the correct power being delivered to all its components at all times. Too little power causes an unstable system, false alarms or non-activations. Too much power, on the other hand will reduce the lifetime of the battery or destroy it.

No power means that the system is running off the battery that is no longer charging. This is fine in the short term, providing that the battery in question is still 100% efficient.

Frequent power cuts, for whatever reason, have a detrimental effect on an alarm battery by reducing its lifetime bit by bit.

Many lower quality Sealed Lead Acid batteries, when fully discharged, do not always recover from a total discharge. This in effect means that thousands of burglar alarm systems in South Africa are literally running off their transformers, particularly in older systems. A good quality Sealed battery should supply a minimum of 6 hours in a standby condition. Hence a reason for an alarm warranty insisting that the system is properly maintained. 

Like PIRD’s, Sealed Lead Acid and Gel batteries do not like heat. They will ensure optimum capacity at around 20°C to provide a lifetime of between five and seven years under normal conditions. The battery life is approximately halved for each 10°C above normal temperature.  If an alarm battery is installed in an area that reaches 60°C. or higher, the lifetime can be reduced to as little as 5 months. In fact, the temperatures in a home that has a tin roof can reach well into the 80’s when the outside temperature is 35°C.

Many installers install the main panel and battery in the roof! 

Pet Alleys…Although great strides have been made in detector technology, we have yet to see a totally fool proof pet “immune” detector that does not compromise the catch performance of the detector.  A cat or small dog may look the size of a human if it gets close enough to the detector. In fact, at close range, a cat may be seen as the size of a tiger. Most pet “friendly” detectors will not detect pets, provided the pet stays on the floor.  

Memory………… All alarm control panels are basically

computer ‘mother boards’. With one or two exceptions of the

older models, all have built in ‘buffer’ memories.

The memory can normally hold up to 1000 events.

There is therefore no excuse for the average Insured not being able to prove his alarm was armed / on at the time of an intrusion.

Disabling an alarm

End of line resistors...

Anti tamper… Press stick…

DISCUSSION TIME