hi i am adding a new garage to the side of my existing unit. i will put a new subpanel in the new structure and wire it to the existing main panel on the opposite wall of the existing garage. the wiring will go up the wall and accross the rafters of the old garage through a non accessable attic and down the common wall to the new subpanel. my question is can i just run 4 separate wires between the panels or do they need to be in conduit or do i need to use a romex type cable. i have another subpanel under the house and the electrician just ran 4 separate wires with no conduit so i was wondering if this is ok or not. thanks for any help.