An electric fence consists of one or more strands of bare steel wire charged to deliver a convincing (but short-lived) electric shock when touched. You can rig anything from a one-strand rabbit barrier around the carrot patch to a “Down Under” multistrand, high-tension fence that carries enough voltage to keep a whole county of winter-hungry deer from your young fruit orchard. I’ll tell you how to design, install, and maintain the electric fencing that’s best for your place . . . or your places. That’s another advantage of electric fencing: Country people do move from time to time, and electric fence is the only form of barrier that is readily transportable.

The Fencer

The heart of an electric fence is the charger, or fencer (Figure 1)., which combines an electrical transformer with a timing mechanism to develop those short, sharp shocks. The current can come from a 6- or 12-volt DC battery, a small photovoltaic system, or from (greatly modified) 110-volt AC household current. The most persuasive chargers are the low-impedance “Energizers” used to electrify sheep fence by the hundred-mile leg in the Australian outback. These turn 110-volt AC power into pulses of 3,000 volts at 30 amps-almost a hundred thousand watts of power and enough to turn a whole herd of sheep into shish kebab were each pulse not limited to a few ten-thousandths of a second. The typical domestic line-powered charger develops only about 4,000 volts at half an amp. This two thousand watts is also a potentially dangerous charge, but each pulse (they come on 50 to 60 times a minute) lasts less than a thousandth of a second. Battery — powered fencers have less oomph behind them, so they release longer pulses — lasting about a half-second each — at a fraction of an AC unit’s voltage.

Output energy (in joules):

This is the maximum energy of a pulse supplied by the energiser to the fence. The higher the output energy, the stronger the electrical pulse to the animal, and the more easily vegetation is destroyed.

• Energisers     with low pulse energy (less than 0.5 joules) are suitable for easily     herded animal species and short fences with no or light grass growth.
• Energisers     with medium pulse energy (1 to 5 joules) are suitable for hard-to-herd     animals and especially for fences with normal grass growth.
• Energisers     with high pulse energy (over 5 joules) are specially designed for long     fences with heavy grass growth.
• Energisers     with MaxiPuls technology provide a powerful pulse for maximum energy to     the end of the fence and consistent performance in extreme fencing     conditions.