IEC 60269-2, IEC 60947-3. UL, CSA. The cylindrical fuse holders have been developed in terms of heat-tolerance and heat emission especially for use with SITOR fuse links and are therefore not recommended for standard applications. SITOR Cylindrical Fuse Holders. Fuse holders for cylindrical fuse links Can also be used as fuse load-break switches, fuse circuit-breakers and fuse holders