Can be done, provided you get a precise match; the electrical wholesaler told me that even the old fuses varied; but you have to remember which way is 'on'. most of them have 'on' on top and 'off' below, unlike a conventional switch ! And, of course, you have to have the equivalent to the fuse you are replacing. I've done it twice; once by an electrician, once myself; but it is really only a stopgap with old wiring. My wiring is 1950s, so the whole house will have to be rewired and pretty quickly.