Bearing insulation failure is a leading cause of motor bearing failures in electric motors. Sufficient amounts of bearing insulation, and having the right kind of insulation, is important for preventing electrical damage. Insulated bearings can help avoid premature bearing failure that can be caused by stray electrical currents. Insulating just one bearing can stop unwanted electrical currents from traveling through the bearing and ground. Seized bearing and mechanical binding are signs of bearing insulation failure. Hearing rasping or scraping noises and feeling resistance when the shaft rotates are other indications that the electric motor’s bearing insulation may be failing.