Electric Fence & Wire, Posts & Energizer

A solar or mains energizer sends a brief, high-voltage pulse along the fence wires. An animal touching the line gets a sharp but safe shock, learns to respect the fence, and stays away. It is a psychological barrier as much as a physical one — far cheaper than a solid wall — and it deters cattle, wild boar, nilgai, blue bull and even elephants when properly built.

Total wire length is the perimeter multiplied by the number of strands (lines) you run. The tool computes the perimeter from your field area or takes a perimeter you enter, then multiplies by the strands to give the total metres of wire to buy. More strands deter a wider range of animals but use more wire.

For a roughly square field, perimeter ≈ 4 × √area — so a one-hectare (10,000 m²) square field has a perimeter of about 4 × 100 = 400 m. The tool uses this to estimate the perimeter when you only know the area. If your plot is long and narrow, enter the actual perimeter for a more accurate result.

Energizers are rated in joules of output, and you size them to the total length of wire (and vegetation load). As a rule of thumb you allow a margin of joules per kilometre of total wire, then round up to the next available unit. The tool suggests the energizer joules for your wire length; always choose a unit a little larger than the bare minimum.

Posts are spaced along the perimeter — commonly every few metres on flat ground, closer on curves and corners. The tool divides the perimeter by a typical spacing and adds corner posts to estimate the count. Corners and gates take stronger strainer posts, so plan a few heavy-duty posts in addition to the line posts.

Grass, weeds and branches touching a live wire drain the charge to earth, weakening the shock the animal feels and running down a solar battery. Keeping a clear strip under the fence — by slashing, spraying or a clearance pass — keeps the voltage on the line high and the deterrent strong. Vegetation load is the most common reason a fence stops working.

The shock circuit is completed through the ground: the pulse travels from the energizer along the wire, through the animal, into the soil, and back to the energizer's earth stake. Poor earthing — too few stakes or dry, sandy soil — means a weak shock. Use enough galvanised earth stakes in moist ground for the fence to bite, especially in dry climates.

Yes — a compliant energizer delivers a very short, low-energy pulse that is unpleasant but not dangerous to animals or people. It is the timing and voltage, not sustained current, that deters. Always use a purpose-built fence energizer, never mains wiring direct to a fence, fit warning signs, and follow your local rules on fence construction and signage.

Properly designed electric fences are widely used to deter elephants, nilgai and wild boar from raiding crops, but large animals need a robust build — strong posts, the right strand heights, a high-joule energizer and excellent earthing. For elephants in particular, follow the designs and regulations recommended by your local forest or wildlife authority.

They are solid planning estimates. Actual wire, posts and energizer needs depend on your field's exact shape, terrain, the animals you face, strand layout and vegetation. Use the tool to budget materials and pick an energizer size, add a sensible margin, and follow local rules and good fencing practice when you build.