Originally Posted by
Paul Johnston
Not a thing wrong with screw in fuses.
Actually, there is - they are very easily defeated and bypassed by the old penny trick or wrapping with aluminum foil.
The NEC has, and for a very long time now, required replacement of overfused Edison base fuses by some other protection means. Basically if the Edison base fuse holder has evidence of overfusing, replacing with another Edison base fuse is prohibited.
Installing Edison base fuse holders is only permitted when they are made to accept Type S fuses by the installation of adapter.
Which all means that if there is evidence of overfusing one is not allowed to install even the correct size Edison base fuse for a replacement, but an adapter for Type S fuses may be screwed in and the Type S safety type fuses may be used.