Shrouded jaws for hook-on type instruments

A pair of relatively movable, shrouded jaws are provided for a hook-on type measuring instrument to insulate the conductive ends of the jaws from contact with high voltage electrical conductors on which the instrument is periodically clamped during its normal application. The shrouded ends of the jaws are characterized by incorporating cup-shaped insulated recesses within which the uninsulated ends of the soft iron magnetic ends of the jaws are disposed substantially below the outwardly extending lips of the recesses thereby to prevent the iron from being inadvertently placed in contact with a high voltage conductor when the jaws are opened to either place them around such a conductor or to remove them therefrom.