Abstract: A high capacity change-over power supply fuse has an elongate fuse element holder, with fuse element mounting positions at each end. Sliding of the holder move one or the other of the fuse elements into contact with contact members mounted on the supply buses. The fuse element not in contact with the contact members is accessed through an aperture in a cover over the holder and contact members, a clip in cover fitting in the aperture. An aperture, is provided at each end of the cover for access to each fuse element when in a non-active position. Only the contact members need be silver plated, reducing the cost relative to conventional rotary change-over units.