People would be very surprised what wildlife will do when hungry or feeding their young. A few years ago we set up 4 test pens/coups. We observed a bobcat jump and clear a 10' run to land inside. This was after he was zapped with 4000 volts. We tried different fencers and it took about 8000 volts to make him hi-tail it and run. I haven't seen him or any other since then. Just a couple of years ago, a coon peeled the plywood off the corner of the house to get into the attic to raise her young.
Wildlife will find a way if there's a way. For those with electric fences, remember that animals tend to have a thicker coat in the winter. A fencer that is quite effective in the summer, may not even be a deterrent in the wintertime. Some say I am overboard with the fencer voltages that I run, however the smaller fencers can lead to a false sense of security with what I've seen. I have to do what is right in my heart to protect the very animals that I accept responsibility for. As long as the fencer is UL approved, it is quite safe for human, livestock, and is fire safety approved.(provided it is correctly installed) Just last week I was reading in the news that all 100 counties of N.C. now have coyotes. I hope I never see one of these.