Stray voltage

Stray voltage is the occurrence of electrical potential between two objects that ideally should not have any voltage difference between them. Small voltages often exist between two grounded objects in separate locations by the normal current flow in the power system. Contact voltage is a better defined term when large voltage appear as a result of a fault. Contact voltage on the enclosure of electrical equipment can appear from a fault in the electrical power system, such as a failure of insulation.

A fallen power conductor from a transmission line forces current through the earth back to the source, which is connected to the earth. The resistance of the earth to current produces a voltage difference between the point of contact and distant earth. If the rate of change of voltage with distance is large, a dangerous potential may exist between the feet of a person in the area.