Electric fencing

Abstract

Since 1958, when details of electrified permanent fencing tried by Massey College became known, hundreds of miles of electric subdivision fence have been erected. The key to its popularity was the great saving in costs of materials, transport and labour. It was also easier to erect, so it became possible for farm labour to construct electric fences instead of waiting for contract fencers. This reduced the amount of cash to be raised still further. Six manufacturers are selling electric fence equipment, and all have well-illustrated leaflets or booklets giving details of erection. In addition, many farmers, encouraged by Massey College, have kept costs very low by using standard bobbin insulators (Type 436) or short pieces of polythene water-pipe as insulators. The success of electric fencing depends on: (a) Careful insulation of electrified wires. (b) A continuous earth-wire running the length of the fence and connected to the earth terminal of the electric fence unit. (c) Removal of stray wires and excessive green vegetation from the fenceline. In practice thistles, grass, clover, secondary growth and tussocks gradually reach the live wires and reduce the efficiency of the fence, particularly in wet or misty weather. Sometimes insulators slip, break or become coated with dirt, so that again electric leakage becomes serious. Further, the 'wind-charger’ units available for inaccessible places sometimes fail to keep the battery fully charged. Consequently a number of electric fences have become ineffective. On the other hand a 'mains' operated unit has been used, and the fence has been checked regularly, electric subdivision fences have been very effective. In fact once the stock learn to respect an electric fence over a period of months, they do not worry it if it happens to be off for some days. Nevertheless, ineffective electric fences are so prevalent that many people hesitate to regard them as permanent, and suggest that they should be reinforced or replaced by standard fences when finance becomes available. This makes it clear that there are definite requirements to be met and limits to its use as permanent fencing.