Abstract: A fuse holder adapter for use with knife-blade fuse clips used with standard 600 ampere fuses in which the adapter comprises first and second metallic plates mounted in facing, spaced relationship on an insulator plate. The first and second metallic plates have respective first and third sections which are adapted to receive fuse clips to form fuse holders of different length and further have respective second and fourth sections formed as knife-blades and extending beyond the insulator plate so as to be able to be receivable in the knife-blade fuse clips used with the standard 600 ampere fuses.