I have a hot water heater located in crawl space under house. There are 2 ea 30amp fuse wired between the heater & the breaker box in the garage. Not sure why the need for fuses since wires lead to 2 breakers.
Problem is the fuses started to blow about 6-7 weeks ago.
I have lived in the house for 4 years without any problems
To replace them I must get under the house in the crawl space.
They last about a week or less & I have to replace them again.
What is causing this & why are they needed.
It would be much easier to just reset breaker.

Your fuses are the symptoms, your water heater is the problem. Could be a heating element is shorting. Most heaters are wired directly from the fuse box and I see no need for additional fuses IF you are correctly connected to the panel. I would start with checking both the top and bottom element. If one appears shoot replace both. If that fixes your issue with fuses just leave them for now.