1) Excess voltage 1) Overpotential 
When the voltage in a circuit or part of it is raised above its upper design limit, this is known as overvoltage.
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. == Explanation == Electronic and electrical devices are designed to operate ...
difference between the operating voltage and the Geiger-M?ller thresholdany voltage between one phase conductor and earth or between phase conductors having a peak value exceeding the corresponding peak of the highest voltage for equipment
The difference between the actual electrode potential when appreciable electrolysis begins and the reversible electrode potential.
excess voltage. · the amount by which the voltage applied to an ionization chamber exceeds the Geiger-Müller threshold.