there is a main distributon panel feeding a 3 phase 225kva transformer 480v primary and 208 secondary.feeding the primary there is two sets 250kcm conductors thhn and one #2thhn gnd, over current protection is a 350a breaker. both sets of parallel feeders are in one 3 1/2 piece of greenfield 17 inches long, total lenth of conductors are 6 foot. my questions; can you run both sets in one conduit? or should they be in seperate conduits like ive alwalys done and will they be subjected to overheating if all are together in one raceway?. also if allowed is there any limit on lenth of conductors?