Noun
flashover voltage (plural flashover voltages)
(electricity) The voltage at which an electric discharge occurs between two electrodes that are separated by an insulator.
Metal grading rings are sometimes added around the disc at the high voltage end, to reduce the electric field across that disc and improve flashover voltage. Source: Internet
Most high voltage insulators are designed with a lower flashover voltage than puncture voltage, so they flash over before they puncture, to avoid damage. Source: Internet