Each of the dinosaur paddocks in Jurassic Park is surrounded by a large electric fence on a dedicated power circuit that is controlled from the Central Control Room. The fences have regular signage warning of danger…

…and large lamps at the top of many towers with amber and blue lights indicating the status of the fence.

When the power is active, both lights are lit. When Dr. Saddler is rebooting the system, the blue light turns on first, with a loud, deep klaxon, meant to signal a “system active, but power is not feeding to the fence yet” status. Although the transition isn’t shown, presumably the amber light turns on as soon as power flows into the fence.

Even though Dr. Grant and the kids weren’t introduced to the light system when they arrived on the island, they were suitably worried when the klaxon sounded and the blue light began blinking. This had the advantage of warning them that the fence was about to activate, but the disadvantage that it set off such a strong fear response in Timmy that he froze in place while still on the fence. Drama is good for an audience, bad for Timmy.

Fence Activation

We see in Nedry’s escape scene that he shuts off the power because the main gates out of Jurassic Park cannot be opened while the power is active. However, in the intro scene (pictured above) we see that the gate can be opened without shutting off power to the entire fence system. This implies that Jurassic Park has fairly detailed control over various parts of the fence system. This is confirmed when we get a glimpse of labels on a circuit board later in the film:

The good

• The major systems are each on dedicated circuits that are individually controlled. That’s useful for managing complex scenarios in the park.
• Automated alert systems are quickly understandable. That’s useful for keeping employees and visitors safe.
• “Blue” and “Orange” are colors that are easily differentiable even with color-blind users. It’s a good choice for alerts.
• There is an unmistakable and unavoidable audio backup to the visual signal.

The deadly

Let’s not forget that this is a system with potentially deadly consequences. It’s worth making sure it does its job of keeping the bad thing controlled, while not frying people.

“Danger” signage on the T-rex pen is too high for good viewing. A person would interact with the fence closer to the concrete barrier, and would almost certainly not look up. Better is to repeat the signage frequently, repeatedly along its length, and at several heights.

The light system is a 4-bit signal. It takes some interpretation. “Wait. What did blinking blue and off orange mean?” That’s pretty poor for emergency situations, where a few seconds of delay can mean the difference between safety and becoming a jurassic kebab.

Better would be an unmistakable binary signal. Light on = power on. Light off = power off. Make it a big, blood-colored red. That’s much simpler and doesn’t require referencing a manual. Color blind folks won’t need to distinguish light colors at all, they can just see the on-or-off.

What about powering up? That blinking is clearly meaningful, but it’s still more ambiguous than it needs to be.

Ideally you’d have some sort of human-detection system so that the fence itself keeps humans safe, but if that’s not doable or reliable, you’d need some other warning signal. I think there are three ways we can convey that shit is getting real…

Visual

I’d recommend a progress bar, like the Eko traffic light concept by Damjan Stanković. Surround the red light with the progress bar, combining with audible and tactile signals, as below. Put these in the pillars that support the cables, and either near or around the hole through which the cables pass, so it’s clear that these lights have something to do with these cables.

Audible

You need the audible warning to catch attention regardless of whether or not a person is looking in the direction of the light. The klaxon is awesome at getting attention and signalling dangers. But again, it’s an ambiguous as The Robot shouting, “Danger, Will Robinson!” If we modified it so that the sound started low and raised in pitch, it would help convey that something is coming on line. You could just use a “blinking” Shepard Tone.

Tactile

And of course, there’s the power itself. It shouldn’t just come on all at once. We should raise the power level over some span of time, so Timmy starts feeling greater and greater discomfort and he has a building pressure to get off the fence, rather than being thrown back immediately. Even a blind, deaf, or panicked person wouldn’t be able to ignore it and be forced to take action without the risk of blunt force electrocution.