We investigate the edge effect on foil fuses in a cylindrical enclosure containing a tamping medium. This type of fuse is being considered for use in microsecond switching of high power electromagnetic pulses. By using the exact magnetostatic solution for axial current lines in a cylindrical enclosure, we find a circuitlike model for the foil fuse and the driving external circuit. The foil resistivity is a function of the joule heat per unit volume dissipated at each position along the width of the foil. In the extreme example given in this letter, we find that the strong edge effects observed at the beginning of the pulses ‘‘heal’’ faster than the time it takes for the foil to switch and hence, edge effects, even in such cases are not important.