Wednesday, July 2, 2014

Pos/Neg fence tips

A normal electric fence consists of:
  1. Wire(s) connected to the fence (positive) terminal of a fence energizer.
  2. The soil’s moisture connected via metal ground (earth) stakes to the negative terminal of the fence energizer.
But the top soil moisture in many areas is too low to be a reliable conductor. In this situation, the animal may receive minimal pain even though a voltmeter touching a steel spike may register 3000 plus volts.
For these sites, one solution is to connect one or more wires in the fence to a second ground stake that is then ‘connected’ via subsoil moisture to the energizer’s ground stake. So some wires are now positive and some are negative—a Pos/Neg fence.
How does the animal receive a shock?
  • On a normal all-positive electric fence, the animal completes the circuit by standing on moist soil (which is connected to the energizer via metal stakes) and touching a hot wire. The current flows down the wire through the animal’s point of contact with the wire to his feet (which are on the soil) and back through the soil moisture to the ground stake.
  • With a Pos/Neg fence, the animal completes the circuit by touching a positive wire and a negative wire at the same time.
When is Pos/Neg wiring needed?
The simplest test is to look at the grass and soil. If the grass has been brown for 3 or more weeks and the top 3 inches of soil are very dry you need it. Second test is to lay the voltmeter’s probe on the dry ground (instead of sticking it in the soil or contacting a metal stake). If less than 2000 volts appear, revert to Pos/Neg wiring. A third test (not advised) is to wait until your animals escape.
Are some energizers better in dry soil situations with all positive fences than others?
IntelliShock & Kube units are superior – particularly the IntelliShock 31 & Kube 4000. They continue to deliver an animal stopping pulse long after traditional low-impedance units (HotShockPatriot, and most other brands) have ceased to do so.
What energizers work for Pos/Neg fences?
All do. From a safety aspect, it’s actually best not to use too large a unit.
What are the negatives of Pos/Neg fences?
  • Fences must be kept very clean. Any conductor (green weed stem or tree, metal post/wire) that touches 2 opposing wires will cause the pulse to drop from powerful to ineffective.
  • An animal or person that remains in contact with both wires (positive and negative) could be killed. That’s why, in Premier’s view, offset metal hot wires should be installed high enough to allow human contact to be broken by gravity.