Electrified fencing was used in Jurassic Park in order to keep animals from leaving their respective territories and therefore protect visitors. There are different types of electrical fencing, ranging in height from rather short to very tall, but all are adorned with warning signs and lights to indicate that the fences are on.
The fencing which surrounds the Dilophosaurus pen is lower in height than the others shown on Isla Nublar, about 7 ft (2.1 m) tall, with the top line of the fence inclined to the inside of the paddock. In addition to warning signs of electrical shock, this fence also had warnings to keep the windows of vehicles rolled up to protect visitors from the Dilophosaurus‘ venomous spit.
The fence surrounding the Tyrannosaurus rex Paddock is, appropriately, much taller, 24 ft. in height and spacing of 30 ft. between posts according to the “Making Of” book. The support beams are adorned with blue and orange flashing lights, whereas the fence containing the Dilophosaurus had only orange lights. The cables are also much thicker, presumably because the Tyrannosaurus is much larger and more powerful than the other dinosaurs. There are also clear indications that 10,000 volts of electricity run through the Tyrannosaurus‘ fence.
The perimeter fence is the only one whose length is actually mentioned–approximately 50 miles (80 km) completely encircling the park. This fence also sported blue and orange flashing lights, as well as a warning buzzer which alerted those nearby to the park’s generator being activated, and therefore that it would be unsafe to approach the fence soon. Additional wiring was place in a crisscross pattern between the main cables of the fence, which may provide additional strength and support.
On Isla Sorna, these fences surrounded the InGen Workers Village, but there wasn’t a good view of it seen in film, however it does appear to be the same type of fencing that was used on Isla Nublar with the similar gate system shown that protected the Helipad compound.
In 2001 we see a different kind of fencing system on Isla Sorna that looks heavier in construction. The fences separated Eric Kirby and Dr. Alan Grant from Eric’s parents and Dr. Grant’s field assistant, Billy Brennan when they had come to the island to rescue Eric, but found themselves also stranded. As stated before these fences seemed to be stronger built than the ones in Jurassic Park and surrounded the Aviary Compound, but was still easily breached by the Spinosaurus. Whether it was due to rust or not is up to speculation.