Abstract: The outer envelope of a capacitor body is provided with an insulation layer and at least the sides are surrounded in consecutive order by a first metal actuation layer, an insulation layer which is deformable or defusable under excess temperature, and a second metal actuation layer with the first metal actuation layer being connected to the first metal conductive layer and the second metal actuation layer being connected to the other metal conductive layer. The construction is such that if there is an increase in temperature in the capacitor body which, for example, may be caused by an overload or a defect, the insulation between the actuation layers will defuse or deform to the extent that the metal layers come in contact and produce a short-circuit which will be effective to throw the capacitor out of the line, such as, by a fusing action.