I missed the 30A bit. It reminded me of one that kept blowing fuse 5 randomly, drove me mad! In the end I found that the harness across the front of the engine had been left after some muppett did the cam belt the wrong way and the harness had dropped onto the front pulley and worn through. At random points the harness would touch the pulley and blow the fuse. To me a while to find that one.