Pulse synchronisation of electric fences

July 2010 Perimeter Security, Alarms & Intruder Detection

Stafix considers the potential danger of ignorant or careless usage of perimeter electric fencing.

The introduction and proliferation of what was essentially an agricultural tool, the pulsed electric fence energiser used for animal control, into urban areas for the purposes of perimeter security, has necessitated a re-evaluation of certain safety aspects of this tool. When used in sparsely populated rural areas, the incidence of inadvertent human contact with electric fences is rare. However, since their effectiveness as a barrier against crime has been appreciated, they have become very popular in urban areas. The likelihood of inadvertent human contact with an electric security fence has therefore increased significantly.

Consider an example of an urban scenario where four houses share common boundaries and all are protected by electric security fences, as per the diagram. Assuming that the energisers installed comply with the stringent international safety standards, how then can this form of security fencing be dangerous? The answer lies in the possibility of a person making contact with more than one fence and receiving shocks from more than one energiser at the same time. This will increase the energy and/or frequency of the shock received. This, besides being illegal and contrary to international safety standards, could possibly cause injury to a person.

For example at points A,B,C,D, and E in the diagram, it is possible for an intruder or a member of the family for that matter, to make simultaneous contact with two different electric fences powered by two different energisers. And, should the four households independently fence all four sides of their properties, the possibility of unacceptably high power levels will also exist along the entire parallel sections of their common boundaries.

Despite the fact that each of the energisers installed at the respective households may be certified to the legal eight joule limit at 500 Ω, should it just so happen that they all pulse in perfect synchronisation with each other, a person making contact with the fences at any of the points A to E will receive the combined shock of two energisers. This could significantly increase the power level to exceed the current legal safety limit. There is also another more likely, and possibly more dangerous scenario: when the energisers are not pulsing in sync with each other. In this case the frequency between impulses could be so close that a person receives two shocks in such close proximity to each other that the fence becomes dangerous and illegal.

Legalities aside, what are the dangers to the person making contact with the fences? The first scenario could result in cardiac arrest and the second scenario, the more likely of the two, cardiac fibrillation. While the likelihood of either of these scenarios occurring is very slim, the industry needs to take cognisance of these possibilities in urban environments.

So what can be done about it? The answer is simple. Have all the energisers on the properties pulsing in perfect synchronisation with each other at legal pulse intervals, and with a combined energy output limited so as not to exceed eight joules. This is exactly what the new, internationally approved, JVA 14 and JVA 28 Security Electric Fence Energizers can be programmed to do and which makes them the ideal choice for security applications.

Finally, to ensure that the installation meets all existing legal standards and impending codes of practice, make sure that you have a copy of the current act and of the SANS 10222 9 (Draft 6) publication.

For more information contact Maurice Williamson, Stafix, +27 (0)82 557 2780, ndlovu@stafix.co.za



Credit(s)




Share this article:
Share via emailShare via LinkedInPrint this page



Further reading:

Hikvision alarms improve protection
Residential Estate Security Handbook 2020, Hikvision South Africa , Perimeter Security, Alarms & Intruder Detection
Hikvision has created a broad portfolio of innovative alarm solutions that are sophisticated, automated, and always fit for purpose.

Read more...
Thermal cameras with artificial intelligence
Residential Estate Security Handbook 2020, Dahua Technology South Africa , Perimeter Security, Alarms & Intruder Detection
Dahua Technology showcased solutions that are important to residential estates, namely perimeter protection.

Read more...
Securing estate perimeters
Residential Estate Security Handbook 2020, Nemtek Electric Fencing Products , Perimeter Security, Alarms & Intruder Detection
Nemtek has a range of products designed to secure the perimeters of estates, however its display at the conference focused on its Network Energizer and its Dual-Action Tension Sensor.

Read more...
Take estate security seriously
Residential Estate Security Handbook 2020 , Perimeter Security, Alarms & Intruder Detection
While the growth in residential estates continues, crime syndicates continue to target lifestyle estates, more often than not using inside information to gain access.

Read more...
Catching the intruder vibes
Residential Estate Security Handbook 2020 , Perimeter Security, Alarms & Intruder Detection
While a fence or wall of some sort is still the foundation for a perimeter solution, a simple barrier is not a sufficient defence against the continual criminal onslaught against estates.

Read more...
Perimeter security decisions
Residential Estate Security Handbook 2020 , Perimeter Security, Alarms & Intruder Detection
There are many options when it comes to perimeter security; Stafix offers some advice to guide estates through the decision-making process.

Read more...
Improved perimeter security with IoT
Residential Estate Security Handbook 2020, Vox Telecom , Perimeter Security, Alarms & Intruder Detection
Vox has introduced an Internet of Things (IoT) solution that helps better protect perimeters by providing notifications when boundary fences have been cut or tampered with.

Read more...
Vehicle and driver identification
Residential Estate Security Handbook 2020, Protoclea Advanced Image Engineering , Products, CCTV, Surveillance & Remote Monitoring, Perimeter Security, Alarms & Intruder Detection
Detecta features vehicle identification (make and model), automated number plate recognition (ANPR), vehicle colour recognition, driver identification, high speed and free flow detection.

Read more...
Wide-area surveillance with early detection
Residential Estate Security Handbook 2020, Protoclea Advanced Image Engineering , Products, CCTV, Surveillance & Remote Monitoring, Perimeter Security, Alarms & Intruder Detection
Being aware of a threat beforehand allows landowners to implement the necessary steps and alert security personnel, and thereby prevent threats from reaching the property.

Read more...
Watch your perimeter
Access & Identity Management Handbook 2020 , Perimeter Security, Alarms & Intruder Detection
SqwidNet collaborated with Teqcon, a South African mechanical and electronic design company, to address the problem of perimeter security in remote locations.

Read more...