Ford,Alternator dead short when power applied.

I have just installed a new 200 amp alternator with a Painless 10120 wire harness. When I check for continuity from the positive battery post terminal to the casing of the alternator or any area of the grounded engine block, I get continuity. So when I hook up the 12v. DC and try to install a 60/70 amp maxi-fuse of course it keeps blowing for I think I am creating a dead short. Is not the isolation post on the alternator where you hook up your 12v to keep the 12v from dead shorting. Why the continuity from positive post terminal to ground areas of motor and body of alternator. There is a