The local feed and grain stores usually carry a product that can help keep the critters from shewing your wiring. Comes under different names but "Bitter Apple" in a pint or quart spray bottle is what I bought. This stuff is so strong and bitter, they warned me not to even think about trying a tiny taste, that when spayed on your exposed wires no critter will touch them.
I think it was only $5 for so and it is easy enough to squirt it on every couple of months. It's worked pretty well here in Arizona where pack rats can be a serious problem. Good luck!
:C