I think the "safety" issue comes up, not because of the age of the equipment, but the maintenance of it, and how it is used. For example, if this service is well-maintained, and continues to support a 1930 lifestyle, no problem. If, however, various occupants have added will-nilly to the system, in order to support the air conditioner, microwave, stereo, bathroom, etc...then there are sure to be major safety issues- of which the service equipment is but a small part.
Ahhh this is hitting close to <new> home now that I've moved in with my fiancee in her turn of the century house... I just recently yanked a couple similar situations off a 10' high ceiling which were feeding what was now being used as a laundry area... behind the fuse holders, the redwood ceiling board was charred from heat eminating from behind these things... (possibly from a fuse not screwed in tight enough?) regardless, the fuse holders are GE. dated 1905.. and appear to have been added as a retrofit after the original wiring was installed.. I've still yet to figure out how old this place is, but there's signs it was pre-electricity..
Most of the fuses of this type, that I still find on occassion were either in a manufactured panel cabinet, or earlier ones in hand made cabinets of 1X wood stock, and aspestos lined. Athough they did not have dead front covers, at least had a door to close. Often painted shut! As these are next to a meter, they may feed other panels! Hopefully they are fused right?
Mark Heller "Well - I oughta....." -Jackie Gleason