I used 6A type B circuit breakers for my servos, however I've got no idea where I got that spec from.
Just had a look in the manual, and it says 15A fuse for 750W motors, however the drive input current is listed as 5.5A (largest motor the drives will do is 750W). I'm guessing the fuse rating is for a quick blow (standard) fuse to give a bit surge tolerance, which normal circuit breakers will give anyway.