Applies to three-pole units for public and industrial distribution systems which are functional assemblies of switches including switch-disconnectors and current-limiting fuses designed so as to be capable of- breaking, at the rated recovery voltage, any current up to and including the rated short-circuit breaking current,- making, at the rated voltage, circuits to which the rated short-circuit breaking current applies.It does not apply to fuse-circuit-breakers, fuse-contactors, combinations for motor-circuits or to combinations incorporatingsingle capacitor bank switches.