Ferraz Shawmut Class R Fuse Blocks accommodate all Class R 250 and 600V power fuses. A choic of screw, pressure plate, and box connectors fit a wide range of stranded or solid copper or aluminum wire. 30, 60, and 100A fuse blocks feature an adder block which can be snapped onto 1, 2, or 3 pole blocks to form multi‑pole segmented blocks of as many poles as desired.