I think Andy is suggesting that one might consider splitting some subsystems out and give each its own fuse off the main power feed. The main feed probably would have its main 50A (or whatever size) fuse as well.

Afterall a good example is our house wiring. Although we may have a 110A service delivered to the house with a main breaker we do not depend upon that main breaker as the only protection. Instead a distribution panel is used with each branch circuit getting its own appropriately sized breaker. (Note for some readers a breaker in this note is a "circuit breaker". We long ago switched from fuses for house power distribution but in some cases fuses are still used).

Michael Karas