I use Premiere1's electric netting, looks equivalent to that in your link. The electricity has never injured my chickens. It has stopped ground based predators from getting in.
Electric netting is different from an electric fence. Electric fences can be set up different ways, some are to keep animals in, some are to keep animals out. If you set them up correctly to do the job you want the to do they can be extremely efficient.
The way it works is that the predator has to complete the circuit between a hot wire and a ground for the animal to be shocked. With electric netting all horizontal wires except the bottom one are hot. The soil is your ground. That means something has to be touching the ground and a hot horizontal wire at the same time to receive a shock. With electric fencing the hot wires are typically installed on insulators to insulate the hot wires while the other metal fencing, the soil, or maybe both can be a ground. Fencing is a little harder to talk about because it can be set up in different ways. I'll stick to netting since that is what I use.
One safety feature is that the electric current pulses, it is not a steady stream. You get about 50 pulses per minute. If it were a steady stream of current you or the critter would not be able to turn loose, which is extremely dangerous. Since it pulses on and off you can turn loose. The instinct for you and critters is to jump back. You don't have to think about it, it's like it knocks you off. The pulsing is what makes it safe.
A chicken's feathers, a chick's down, and an animal's fur provide insulation. With a chicken the feet, legs, beak, combs, and wattles are not insulated. I've seen chickens standing on the soil (their feet are touching the soil which is the ground) touch a hot wire with their beaks, wattles or comb when they are pecking at grass or something in the netting. They squawk, jump back and up a couple of feet, and them go back to eating. They are not injured but they do learn to not peck around that netting.
My baby chicks can go through that netting until they are about 7 to 8 weeks old. It's not so much that down or feathers insulate them but they jump up a bit to go through one of the openings. They are not touching the soil and the hot wire at the same time so they don't get shocked.
Fur covered predators have bare feet soles. Those touch the soil and provide the ground. Their noses, lips, and tongues are bare. Some of them like coyotes or some dogs could jump over that 48" high netting but they don't. They explore that netting with their tongues or noses and get shocked. Once is usually all it takes, they run away and don't come back. I had one thickheaded dog where once wasn't enough. She had to get shocked twice to learn that lesson.
That's the way it is supposed to work but I have seen some things. I've found three different turtles trapped under the netting as they tried to push their way under. They were too slow to be able to jump back. Every time the current pulses you could see them jerk. I turned the current off and got them out of the netting. Two of them eventually wandered off. The other died, it was probably there all night. I've found a couple of dead frogs that got tangled up in it. One time I found a big possum tangled in it. It was literally tangled and could not let go. It was still alive when I found it but getting shocked every time it pulsed. I killed it, the electricity didn't. A neighbor found a dead 5' long snake in her electric netting. It was headed into it and couldn't get out.
I'm not going to tell you that there is absolutely no risk, there is risk in anything you do. I've never had a chicken or chick injured by the netting and I've accidentally touched it a few times myself. I haven't lost a chicken to a ground based predator since I set up the electric netting. I consider the risks to be extremely small comparted to the benefits of predator protection.
