Although electric submersible pumps (ESPs) have been produced for almost 100 years, the actual causes of certain electrical failures are still unknown. Why do failures occur on startup or two weeks after an electrical storm? Most of the answers to these questions can be found from an analysis of traditional grounding techniques and consideration of how electrical insulation fails. ESPs are predominantly operated on ungrounded power, which can lead to arcing faults and residual charge. Frequently the wellhead is not even used as a ground. At other times cathodic protection installers insist on no other connections to the wellhead. Some ground wire connections can actually exacerbate the electrical damage done by lightning. Three-wire power systems are still quite prevalent in the oil field. Ferroresonance and lack of third-harmonic magnetizing current can produce very distorted waveforms. All these topic are investigated. A consensus seems to be building that one grounding configuration does provide superior reliability.