On Tuesday, December 8, 2015 at 1:00:12 PM UTC+3, Eric Munk wrote:
As mentioned they are no longer mandatory in The Netherlands. They were
introduced in the 1960s I believe after a string of accidents (some fatal).
Since then fields have become a lot bigger, obstacles a lot less and air
traffic a lot busier. We opted to replace all fences around the airport by
ditches, and deleted them from our fleet to improve on look-out. Also,
modern gliders seem less prone to injure pilots compared to the older ones
where the wire would go into the gap of the canopy front (compare K8 line
of fuselage/canopy to discus and you'lle see what I mean).

From the New Zealand point of view, several things have changed:

- at the dawn of electric fencing, it was common to distribute it via a single high tensile wire quickly added to an existing fence using risers. These could often be quite high so that vehicles could pass under the electric wire at gates, and also so that risers were only needed every 5 or 10 posts.. As it was a single wire and the risers perhaps only 2x1s it was not easy to see.

- Since at least the early 70s new electric wires have been added as part of the main fence using staples over plastic insulators, and gates are traversed by routing the electric wire through a buried plastic (alkathene) pipe..

- at first, temporary fences for break-feeding (subdividing a paddock) used solid wire. Since, again, the early 70s, this has been universally replaced by stranded plastic (usually orange) with very thin aluminium filaments to carry the current. Besides being many times lighter to carry and many times easier to roll up and unroll somewhere else, it will also break before doing much damage. Many was the time, as a lad, that I rode a motorcycle through such a fence by accident.