I just changed a fuse panel fed from three wire fuse disconnect. I installed CB panel. I did not run four wires to this new panel, should I have run four wires. The new panel is right next to the disconnect.There was no place to land a 4th wire unless I drilled and tapped to side of disconnect. I did run a ground wire from water line to this panel attacted it to the neutral bar, which I think maybe I should not have done this. This is a very old building and none of the circuits had grounds.