Applies to fuses for outdoor and indoor installations, for a.c. voltages above 1000 V. The characteristics of the fuses and requirements in respect of all tests are enumerated in detail. An application guide is provided in an appendix and a further appendix deals with standardization of time/current characteristics and dimensions; the latter appendix is intended to rationalize the large number of differing fusing characteristics and sizes of fuse links available, and gives values of preferred time/current characteristics and preferred dimensions for fuse links having rated currents in the range 1 to 400 A.