A patience trying horse gave Bill Gallagher the idea of electrifying objects and led to the development of electric fences.

Anyone who has ever put their hand on a farm fence to find it sends a bewildering pulse of electricity up their arm will appreciate the effectiveness of farmer Bill Gallagher's invention to keep a horse away from his car. An invention that paved the way for the invention of electric fences.

Bill Gallagher lived in the Waikato in the 1930s and was bothered by a horse named Joe who had a love for scratching its flank on the family car; but Joe was in for a shock. Mr Gallagher, while watching the old horse rocking the car, put his inventive mind into action and came up with a solution to stop it from happening. He electrified his car. Every time the horse rocked the car as it scratched itself, a triggering device sent a current through the car and consequently Joe. Joe quickly learnt the old Essex car was not such a great backscratcher after all.

Bill Gallagher quickly realised the use of electricity need not be restricted to cars and horses, in fact it has probably never been used for this purpose since, and by 1938 his experiments with electrifying fences became the basis for the Gallagher Power Fencing company.

Bill Gallagher had never really enjoyed the day in day out routine of dairy farming and was only too pleased to be working doing what he loved instead - finding practical solutions to problems and making things.

The electric fence was an invention which not only became a successful business worldwide but which also changed the nature of pasture management practices in farming. New Zealand is famous for inventing new ways of becoming more efficient and making gains in the agricultural area. Collectively all of these gains have made New Zealand farmers the best in the world. The electric fence was one of those inventions that increased the country's competitiveness as well as earning money through international sales.

To begin with, Bill Gallagher linked about a mile of fencing on his dairy farm to the mains power supply. Though this worked well it was illegal to use the mains power supply in this way and he was ordered to disconnect it by the authorities. Next he developed electric fences powered by a battery and the electric coil from a car. A system which worked well once he had worked round the problem of it short-circuiting by wrapping the coil with heavier wire.

Bill Gallagher knew by 1940 there was a market for his electric fences. "The neighbours wanted these things, so I made them some.... I'd make half a dozen and go out on the road, sell them, leave them on a month's trial.... and people would mostly pay for them," he said.

One of the earlier electric fences worked mechanically with a mercury switch as part of the timing device. A motor rocked a horizontal tube of mercury side to side, which had electrical contacts at each end, so that whenever the tube was flat the mercury connected them. Mercury is a liquid, and because it is also a metal it is a very good conductor of electricity and was ideal for this ingenuous system for regulating the pulse through an electric fence.

Nowadays the fences are all electronic and work with transistors, capacitors and computer chips, which are more efficient and effective even though the old mercury model is still operational today at the Gallagher premises in Hamilton.

By 1964 the company had made over 20,000 electric fence units and the agricultural research station at Ruakura in the Waikato strongly supported the use of the fences by farmers.

Indeed the use of electric fences led to new farming practices especially in the dairy and beef industry that the Waikato is famous for. It gave farmers much greater control over their pastures.

Because the fences were light and portable they could easily fence off an area of a paddock and put the cows in there, thus carefully measuring how much feed they could eat as well as leaving other areas of the paddock to grow.

During the 1950s and 60s the range and effectiveness of electric fences was increased and in 1961 the law was changed making it legal to run electric fence energizers off the mains electricity supply. This allowed an improvement on the old battery models which could not deliver a high power pulse beyond a limited distance. Also the powerful charge pulsing through these new fences meant that they were virtually unshortable, any vegetation that touched them was literally burnt off. It was very important for the fences to be reliable, especially the portable ones, as they partly work because cows learn it is not a good idea to touch them. If they decided to walk over an electric fence, all at once, it would simply fall down. If the cows do not get a shock every time they touch the fence they will not learn never to go too close to one.

With a reputation for quality products the company decided to expand overseas. Inspired in the 1970s, Bill's two sons William and John realising the company was years ahead of electric fence makers in Europe and the US, they decided to exploit the advantage and began looking for markets overseas.

Today the company, which grew from humble backyard beginnings, is a world leader in agricultural electric fencing and exports to all four corners of the globe and employs over 300 people in New Zealand alone.