The FWH-125B is a 500V high-current fuse designed for industrial power distribution and protection applications. It is rated for 125A RMS and features a pre-arc I²t of 800 and a total clearing I²t of 3500 at 500V, with a power loss of 25 watts at rated current. The fuse operates with a power factor of 15% and includes arc voltage characteristics that allow peak arc voltages to be calculated as a function of applied working voltage. The FWH-125B is part of the FWH 500V series (35–1600A range) and is recognized by UL for amperes from 35 through 800. This fuse is commonly used in electrical distribution systems, motor protection circuits, and industrial equipment where reliable overcurrent protection and fast clearing times are essential.