electrical issues
 

I am having a problem with my 100 amp fuse blowing. I have power from the battery, but when I turn the key I loose everything, all power. Once I take the key out I have power again. I thought the battery was low so i connected the jumper cables and that is when the 100 amp fuse blows. I dont have to turn the key for this to happen, and at this time the lights stay on no matter what.
Can this be the ignition switch short? Or if anyone else might have had or heard of this issue can you let me know.
thanks.
Tim