I don’t come across cable damage by mice that often but when it does crop up the damage can be costly to repair. From the few examples I have seen the damage is usually to the grey or white outer sheath of domestic cables. Not very often is it right though the insulation to the copper wire. This could be because the mice get a tiny tingle shock as they start to reduce the thickness of the inner insulation then stop biting or it could be the inner insulation layer has a different texture. In my experience I have found mouse damage when investigating alterations or other unrelated faults. Note that I wear gloves when feeling about blindly for cables under floors and in roof spaces because I don’t want to touch a live cable, a dead mouse or even a live mouse! The properties affected have been either rural locations or backing onto fields, particularly arable crop fields. I understand that Field mice for example or not considered a pest so dealing with them in a property can be problematic. In the recent example there was also damage to frost protection insulation on water pipework in a loft. To avoid expensive consequences I would recommend dealing very promptly with any signs or sounds of mice in a home, before it becomes a very expensive and disruptive repair.