Check the manufacturers nameplate. Most equipment will state weather or not a fuse is required. For instance, if a piece of equipment states a maximum fuse size of a specified value, you must use a fuse to protect the unit. Doing otherwise would void the listing and be a violation of 110.3(B). If it states maximum fuse or circuit breaker you could use either. You could use a breaker as protection and a non-fused disco at the unit.