An overvoltage protection device includes first (120) and second (130) electrically conductive electrode members and a varistor member (110) formed of a varistor material and electrically connected with each of the first and second electrode members. The overvoltage protection device includes both: an integral first fail-safe mechanism (161) configured to electrically short circuit the first and second electrode members about the varistor member when triggered by a first set of operating conditions; and an integral second fail-safe mechanism (141) configured to electrically short circuit the first and second electrode members about the varistor member when triggered by a second set of operating conditions different from the first set of operating conditions.