Wiktionary
n. 1 (context physics English) The difference between the electric potential of an electrode or cell under the passage of a current and the thermodynamic value of the electrode or cell potential in the absence of electrolysis; overpotential. 2 The hazardous condition that occurs when the voltage in a circuit is raised above that for which it was designed.
Wikipedia
When the voltage in a circuit or part of it is raised above its upper design limit, this is known as overvoltage. The conditions may be hazardous. Depending on its duration, the overvoltage event can be transient—a voltage spike—or permanent, leading to a power surge.
Usage examples of "overvoltage".
She cleaned out hundreds of urchin nests, destroyed infestations of fireworms that had wrapped themselves around electrical cables and caused crippling overvoltages, went up against and killed makos and mantas and spinners.