The recommended 100A DC fuse for the SureSine may seem excessive. However, because the inverter has a large amount of input capacitance, upon startup the unit can potentially draw much higher currents than in steady-state. In order to prevent inadvertent blowing of an undersized fuse, a 100A fuse is recommended. This size provides the necessary protection to the system wiring, while also allowing the inverter to draw its large startup surge without tripping. Using a fuse rated less than 100A will risk nuisance tripping when the inverter is powered up.