Solving ‘coastal click’

March 2016 Residential Estate (Industry), Perimeter Security, Alarms & Intruder Detection

Coastal click, a phenomena experienced predominantly on electric fence installations along coastal areas, but which can also occur in very dusty areas, is caused by salt or dirt build-up on insulators. This results when there is a dew or light mist in current tracking across the now salty or dirty conductive surface of an insulator and arcing onto a support post. The resultant ‘click, click’, or worse, ‘klack, klack’, aside from being annoying can lead to false alarms being triggered.

Until the 1980s the maximum output voltage of an electric fence energiser was capped at 5000 volts. With the advent of solid state electronics and improved, safer circuity, this cap was later lifted to 10 000 volts. The problem, however, is that insulator design did not keep pace with energiser power output and when steel supports are used, as is the case with most electric security fences, tracking becomes a problem.

The solutions to this problem to date have been to periodically wash down the insulators, which is time consuming, or alternatively to resort to large, bulky, agricultural type insulators which are not attractive around a prestigious estate. Bi-polar fencing is proving to be an attractive solution to this irritating problem and is being increasingly used by many of the country’s top installers.

Bi-polar fencing

The wiring configuration of a conventional electric security fence is generally configured with alternate live and earth return wires. This is done because an intruder wearing rubber soled shoes will be insulated from the ground and thus will not receive a good deterrent shock. It is in fact necessary for an intruder to touch both the live and earth return wires to receive a shock.

So what is bi-polar fencing? On a bi-polar fence a positive pulse is transmitted along one wire and a negative pulse along the next wire. This means that every wire on the fence, with the exception of one true earth wire, is now live and, just as with a conventional electric fence, when both wires are touched the intruder receives the full shock.

The big difference, however, between a bi-polar and a conventional electric fence is that voltage on the wires on a bi-polar fence is half that of the single live wire configuration and this reduction in voltage, while in no way reducing the security provided by the fence, eliminates the tracking and annoying clicking and false alarms.

Nobody can tell the difference between touching the live and earth on a conventional electric fence and the live and earth on a bi-polar fence because the shock is exactly the same. So the net advantage of bi-polar fencing is improved security with all wires being live, all wires being monitored and no annoying coastal click.

Finally, the use of JVA bi-polar energisers, in conjunction with a JVA Windows compatible Perimeter Patrol electric fence software management package, with its optional High Level Integration program (HLI) has become the electric fence management tool of choice among many of the country’s professional fence installers. JVA bi-polar energisers and Perimeter Patrol software can use either hard-wiring, fibre optics, GSM or Wi-Fi for information transmission giving the end-user peace of mind and a comprehensive solution to their perimeter security challenges.

For more information contact Ndlovu Fencing t/a Stafix Electric Fence Centre, +27 (0)33 342 6727, ndlovu@stafix.co.za, www.stafix.co.za


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