I am using Bachmann Nickel Silver HO EZ-Track.  I have an outer loop using 22 inch radius track and an inner loop using 18 inch radius.  I want to connect the two loops using the #6 Crossover switch unit.  However, I want to isolate the two loops (electrically) and run one train on each loop with two power supplies.  I want to be able to switch either train to either loop.  What do I need to do?