Well, I have been looking to get an answer to the fuse sizing for my gecko 251Xs. If you look on the gecko site, FAQ, under fuse recommendations, it says that slow blow fuses may not save your drives and to select an amp rating that you don't want to exceed. Well duh? The question is how to figure that out. (they have a comment in parenthesis too... 7amp for steppers, 20amp for servos). My confusion is I thought the fuses were for the drives. The drives are rated at 3.5 amp, but that's output. Docs only list warming for exceeding voltage limits. So what are the amp limits for fuse sizing?