Winnie ia a wire chewer around here and has tried teaching the others. PVC pipe works but my computer has paper towel and toilet paper tubes over the cords. If you have things with those big box plugs, they paper tubes can be cut, fit around them and taped back shut. They've worked for me and even gave my cable guy a laugh when he gave me a new modem. (it was worn out not destroyed by kitty teeth)
Good luck!!!

Oh, on my refrigerator in the kitchen, I got some plastic wire covering from Walmart. It is slit down the side but curls closed and they can't open it. It was pretty expensive to do the entire house with it. That's why I went with the paper tubes. They are cheap and easy to replace and should at least slow him down.