A capacitor header for coupling a voltage output from a capacitor, the capacitor header characterised by: a live output plate for electrically connecting to a central live conductor of the capacitor; a ground output plate for electrically connecting to a ground conductor of the capacitor, the ground output plate comprising an aperture for allowing connection between the live output plate and the central live conductor; a first insulating member and a second insulating member each arranged at least partly within the aperture of the ground output plate, wherein each of the first insulating member and the second insulating member comprises an aperture for allowing connection between the live output plate and the central live conductor, wherein the each of the first insulating member and the second insulating member comprises a non-planar mating surface, and wherein the non-planar mating surfaces of the first insulating member and the second insulating member interleave each other to form a non-linear path between the ground output plate and the apertures in the first insulating member and the second insulating member; at least one insulating seal between the non-planar mating surfaces of the first insulating member and the second insulating member; a first set of one or more insulating sheets between the ground output plate and the second insulating member; and a second set of one or more insulating sheets between the live output plate and the second insulating member; wherein the first set of one or more insulating sheets and the second set of one or more insulating sheets extend beyond an outer perimeter of the live output plate and the ground output plate. a live output plate for electrically connecting to a central live conductor of the capacitor; a ground output plate for electrically connecting to a ground conductor of the capacitor, the ground output plate comprising an aperture for allowing connection between the live output plate and the central live conductor; a first insulating member and a second insulating member each arranged at least partly within the aperture of the ground output plate, wherein each of the first insulating member and the second insulating member comprises an aperture for allowing connection between the live output plate and the central live conductor, wherein the each of the first insulating member and the second insulating member comprises a non-planar mating surface, and wherein the non-planar mating surfaces of the first insulating member and the second insulating member interleave each other to form a non-linear path between the ground output plate and the apertures in the first insulating member and the second insulating member; at least one insulating seal between the non-planar mating surfaces of the first insulating member and the second insulating member; a first set of one or more insulating sheets between the ground output plate and the second insulating member; and a second set of one or more insulating sheets between the live output plate and the second insulating member; wherein the first set of one or more insulating sheets and the second set of one or more insulating sheets extend beyond an outer perimeter of the live output plate and the ground output plate.