I'm assuming you don't mean he's electrified your fence, merely that he's run an insulated cable along it to provide some power to his shed, or a garage or whatever. If that's the case, then he's probably within his rights, but it would certainly have been polite to have asked you first. He may even think it's his - I certainly wouldn't know without checking which of my fences I own.
If, on the other hand, you mean he has actually electrified your fence, is there anybody you don't much like you could ask to come round and give you a hand with a small gardening project?