(We ran a feature on shock sensors and where best to use them...)
"Ask any estate agent what three factors will sell a house and he will invariably reply 'position, position, and position'. Similar criteria are true when wishing to obtain the best performance from an intruder detector. The installer may have the best detector at his disposal, but if it is installed in the wrong position it is handicapped and thus may give rise to false alarms or fail to detect when illegal entry is made. The other quote that has parallels in the security industry is that 'poachers make the best gamekeepers'. The alarm installer must try to identify any possible weakness in the building's construction that the intruder will possibly exploit, and potential external factors which may degrade the equipment's effectiveness."
Hodge's history lesson
(George Hodge – now our Technical Consultant – looked at the pros and cons of dual and single technology detectors. He started with a short history lesson...)
"Once upon a time, burglar alarm systems were constructed from simple solid components which rarely went wrong. Detectors were mechanical barrier-type detectors, such as foil and Directly Applied Continuous Wiring or a switch operated directly by door and window movements. The control unit was constructed from discrete components and an alarm caused a thumping great relay to energise. Reliability was much like an electrical installation, which is pretty high, and false alarms were rare. Then movement detectors were invented and the alarm installer's trouble began.
"Movement detectors were prone to false alarm for a variety of reasons not immediately recognised by installers. Attention had to be paid to their correct positioning, the environment had to be friendly and they had to be mounted firmly on the holding surface. All these points were slowly realised by the then small security industry and taken into account. As it grew and traditional repair by component methods changed to replacing the complete item, less skilled installers emerged and the false alarm rate rocketed – the hunt was on for a foolproof detector which would only alarm at the right time regardless of its positioning or the environment."
Faulty towers
(In a Skill School feature, contributor Bill Owens told us about 'Resolving Intermittent Faults' and listed some possible causes...)
"Mechanical damage to cable insulation is one possibility, caused perhaps by cable clip penetration during initial fixing, wear due to tightness around a corner, or wear due to the cable path under a carpet rod, and so on. Mechanical damage to components can be due to lack of care during manufacture and/or subsequent installation.
"Dry joints are the result of poor soldering techniques and/or natural ageing of the joint. Chemical action can be the result of oxidisation of twisted wires or corrosion of component leads. Unsuitable product – using a device outside its design parameters or in a marginal situation – can also cause an intermittent fault.
Most potential causes come down to just plain bad workmanship and could, with a little bit of forethought, have been avoidable."
Inspector Lynskey, I presume
(Our 'People' page carried a report on a present-day columnist...)
"A founder member of the Security Services Association (SSA), Michael Lynskey has been appointed Inspector for the North of England. He was previously running his own company, installing intruder and fire alarm systems, locks and safes as well as CCTV and door access."
Source
Security Installer
