any downside to replacing the 30 amp fuses with 15s, I strongly suspect over the years they were put in for no good reason.
(230 circuits are on separate pulls)

Check the wire sizing to determine the correct fuse size. You do it wrong and the wire will act as the fuse.

ETA:
15a = 14g wire

30a = 10g wire

Big difference in loads

And then your house burns down, which isn't all it's cracked up to be.

That is how my house was when I bought it.  I'm in the process of upgrading the electrical service right now.  The fuse box has 4 fuses and all of them were 30 amp fuses.  The scary part was I was blowing them!  After a little while I figured out which circits were using the same fuse and then changed where I had things plugged in.  I've moved them back down to 15 amp fuses now and haven't had a problem.  I found out some of the outlets in the bedroom, living room, and laundry room were on the same circuit.  Running a window air condition and washer  was actually pushing the circuit and when I would plug in a vaccume, pop, no more power.

Buy some new 15 amp fuses and watch which circuits you are using if/when one blows.

It will reduce heating costs.

ollld house, wiring not accessible to check.

A sub panel was added with breakers for a few grounded outlets and the appliances.

There are some 15 amp fuses laying around, but every one in the panel now is 30 amp.
Only thing that should be running off these circuits now is lights and a few outlets.

I am assuming the problems comes in upping the fuses past the wire ratting. Downgrading should do nothing other then blow if it is overloaded?

your WHOLE house is run off 4 fuses!1!!!!!!1??

ouch.


I have 30 breakers now- and need more!!!

to me it sounds like some dumbass thought she could run more stuff with bigger fuses...no good.  WOuld suggest you have circuit breakers put in and seperat some of those runs into more breakers.

You can downsize the fuse i.e. 30 to 15 or 30 to 20 but do not up size if you don't know the wire size.

I'd figure out a way to access it.





 

The wire will be accessible at the fuse panel.
Take the cover off and look.

While not a sure thing (it could get smaller elsewhere) if you see #14 at the panel the limit is 15 A.

Only in the short term, though it's a fantastic way to clear out the attic and basement of unwanted junk.