Electric Fence

The Electric Fences were used to contain the cloned dinosaurs in the park, and some areas of Site B.

On Isla Nublar
The fences were first seen in service on Isla Nublar. They were anywhere between ten to thirty feet tall! They had a minimum of 10,000v of electricity to stop the dinosaurs from attempting escape, however, this was their fatal flaw as well, because it didn't have enough to critically wound any dinosaur larger than a human (but it could still do some injury).

On Isla Sorna
On Isla Sorna there were several broken down electric fences and in there was a special type of electric fence that had metal bars and spikes on the top (for the Velociraptors because they could climb). Due to the age of the fence and lack of maintenance, the Spinosaurus crashed trough the fence easily.

Debate
The electric fences required at least 10,000 volts of voltage to contain the dinosaurs properly, this is an assumption, as mention is made about whether or not direct current or alternating current was used. Also, it should be noted that it is in fact CURRENT not VOLTAGE that kills things (at least with the Tyrannosaur). It is assumed the same voltage was used for all the other dinosaur enclosures, although too high a voltage for certain animals, it would most likely kill them depending on their size, and preventing dinosaur deaths was a big concern. The fences were electrified to discourage the dinosaurs from attempting to escape. Certainly it's okay for a Tyrannosaur to take a mild 10,000 volt shock probably along with the Triceratops and Stegosaurus due to their thick hides and size, but that type of voltage would likely kill smaller dinosaurs.

The Dilophosaurus in the park were "genetically altered" into being 3ft tall and presumably poked their heads through the fences to get a better shot when they spit their venom. The Compys roamed around in 2-3 large groups in different enclosures. If one of the compys were to hit the fence by mistake, it is certainly not likely to survive.

The Tyrannosaurus perimeter fence has 1 main design floor. You can see that the larger Fence posts have ceramic guide bolt to fix each horizontal wire onto the fence post. However between each of the larger posts are a smaller post which each electric wire makes direct contact with, sending the current straight to earth.