A Safari Park has a problem with monkeys escaping from a fenced area that had existing electric fencing on the chain link fencing. They were observed to be climbing up the posts placing hands and feet between the wires and so escaping from their enclosure.
The solution to this was simple and entailed creating loops of live wire around the posts standing proud about 20cm off the posts using Offset or Distance insulators to prevent the monkeys from reaching the posts to start with.
A similar problem was observed in the past where Elephants were seen to thread their trunks through the live wires to hold the post and pull it over. In this case, running a live wire down the post so preventing the animal from curling it's trunk around the post was effective.