FRN-R-4 is a 4 A, 250 V, dual-element time-delay fuse from Bussmann's Fusetron FRN-R family (UL Class RK5), designed to protect circuits by tolerating brief overloads from inrush or startup currents without nuisance blows. The standard body size is approximately 14.3 mm in diameter by 50.8 mm in length (about 0.56 in x 2.00 in), with an interrupt rating up to 200 kA at 250 V AC. This FRN-R-4 variant is cataloged across official Bussmann/Eaton literature and distributor listings as the 4 A, 250 VAC, dual-element time-delay option in the FRN-R RK5 line.
