The voltage over and above the voltage predicted from standard tables of reduction potentials that must be applied before an electrochemical reaction occurs at the expected rate.

The difference between the actual potential of electro-chemical reaction and the theoretical value at which the reaction becomes balanced.

An increase in voltage outside the normal tolerance lasting greater than one minute. Also known as swell.

By definition, a voltage that is at least 10% above normal. (See Spike and Surge.)