Abstract: A head type current transformer having an aluminum head housing mounted on top of and supported by a porcelain insulator. The head housing and insulator together define an enclosure housing therein an, insulated, electrical component immersed in a liquid dielectric. The transformer unit is rendered explosion resistant by having a shock wave attenuator located at least partially in the liquid in the vicinity of the juncture of the housing and insulator to reduce the force of a shock wave originating in the head housing below that which would cause fracturing of the porcelain insulator. A selected area of the wall of the head housing is also patterned to facilitate its rupture in a predetermined area which is in the region of the highest voltage stress area. A filler material of felt is also used to displace a portion of the oil dielectric at the area of weakness.