Plenty of houses still run on fuses, and a fuse panel that has been maintained and never tampered with is not automatically dangerous. A fuse is a very reliable device. It has one moving part, which is the metal element that melts, and it either works or it is gone.
The difference shows up in how people live with them. A breaker resets. A fuse has to be replaced, which means someone has to keep spares, has to know the right rating, and has to be willing to walk to the basement in the dark. Each of those steps is an opportunity to do something unwise.
The classic unwise thing is over-fusing. A circuit that keeps blowing a fifteen-amp fuse gets a twenty or a thirty put in instead, and the nuisance stops. So does the protection. The wiring behind the wall is still fifteen-amp wiring, and it is now connected to a device that will happily let twice as much current through it indefinitely. Type S fuses with their adapter bases were introduced specifically to prevent this, because once the correct adapter is screwed into the socket a larger fuse physically will not fit.
Capacity is the other practical limit. Fuse panels were typically installed alongside sixty-amp services in an era when a house had a refrigerator, a few lights and a radio. Adding central air, an electric range, a dryer and a modern kitchen to that service is not something the panel was ever meant to do.
There is also an insurance dimension. Some carriers ask about fuse panels, some price around them, and some decline. That has less to do with fuses being inherently unsafe and more to do with what tends to be found alongside them, which is a house whose electrical system has not been touched in sixty years.
The honest summary is that a fuse panel is not an emergency, but it is a constraint. It limits what the house can support and it puts a decision in the hands of whoever is holding the replacement fuse.
If a fuse panel is staying in service for the time being, three habits make it much safer. Keep correctly rated spares where anyone can find them, fit Type S adapters so the wrong rating cannot be installed, and note which circuit each fuse serves on the inside of the door. None of that costs much and all of it removes guesswork on a bad evening.
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