Quick google search on "rabbits chewing cables"(no quotes) turned up: [link|http://www.beal-net.com/laluna/chew.html|Chewing and Rabbit Proofing]
Very young rabbits may not be problem chewers because their teeth are still developing. However, when they hit adolescence, as young as three months, most rabbits begin to chew like there's no tomorrow. They attack carpet, ... and electrical wires (among other things). Maturity, and spaying and neutering, will help ease this hormonal rage, but chewing is a life long issue that must be addressed.