If you are talking about the "Fuseable Link" (or fuse as you said) that is inline in the main Hot wire from the battery to the fuse panel, and it is blowing then you do have a direct short in your 12-VDC electrical system. Your 110-VAC electrical system has nothing to do with your problem.
First, you should remove ALL of your fuses from your 12-VDC fuse panel (write down which fuse went where).
Then you should inspect this main wire for damage or shorts and then and trace it to the 12-VDC fuse panel.
If you do not find any damage or shorts then replace the inline fuse and see if it blows without there being any fuses in your fuse panel.
If it blows then you have a short to ground somewhere on your fuse panel. If it does not blow then replace your fuses one by one until you find the circuit that has the problem, then trace the wiring from that fuse.