100 Amp Cartridge Fuse Box - Make sure this fits by entering your model number. 100 Amp (100A) 600V Dual Element Time-Delay Class RK5 Fuse UL Listed This ECSR-100 could be used to substitute for Bussmann FRS-R-100, Littlelfuse FLS-R-100 and Ferraz Shamwut/Mersen TRS-100R. Buy 5 Littelfuse 0695020 Mcase Cartridge Fuse 20 Amp 32 VDC: Cartridge Fuses - Amazon.com FREE DELIVERY possible on eligible purchases. The Cooper Bussmann FRS Series 30 Amp Brass Cartridge Fuse is a dual-element fuse with time delay. This class RK5 cartridge is intended to be used with current-limiting applications at 10 seconds (minimum) at 500% the rated amps..