Littelfuse Fast Acting 3AB Fuses - 314 Series The Littelfuse 314 series of fast acting 3AB fuses are ceramic bodied and as such permit higher interrupting and voltage ratings. Ideally suited to applications where high current loads are to be expected, the Littelfuse 314 series fast acting 3AB fuses are best used as supplementary protection in appliances or utilisation equipment providing individual protection for components or internal circuits.