interrupter 16 are coaxial with one another on the common axis 18 the interrupter 16 has a fixed contact arrangement 20 a movable contact assembly 22 an annular electrode 24 and an arc driving coil 26 in this embodiment the fixed contact arrangement 20 is formed directly on the end of the main conductor 14 the arrangement 20 has a contact tongue 28 integrally formed with the conductor 14 although for clarity the tongue 28 is shown extending from the conductor 14 it will be readily apparent that in other arrangements the tongue could be formed in a recess in the conductor 14 a shield 30 of insulating material is mounted on the conductor 14 adjacent the tongue 28 the arrangement 20 is terminated by a conductive tube 32 mounted on but being electrically connected via the coil 26 to the end of the conductor 14 the outer surface of the tube 32 provides an inner first arcing surface 34 which is coaxial with the common axis 18 the coil 26 is mounted within the tube 32 coaxially with the surface 34 and is electrically connected at its inner end 36 to the conductor 14 and at its outer end 38 to the tube 32 the movable contact assembly 22 consists of a pivot block 40 on which is mounted contact blades 42 for angular movement about the pivot axis 44 the blades 42 are resiliently urged together by spring device 42a connected between them and in a make position engage.