where a fuse has been removed,it should be retained by the person working on the equipment until the job is finished. A check should be made that any interlocks or other safety devices are operative. Additional precautions are necessary to ensure safety when work is to be undertaken on high voltage equipment (desired to operate at a nominal system voltage in excess of lkv) The work should be carried out by or under the direct supervision of a competent person with sufficient t knowledge and a permit to work system should be operated