I want to put a subpanel in my unattached garage . Heres my work so far I've had to run new 10/3 to the garage from the main panel because the old wire was only 10/3 no ground . Now I plan on driving 2 grounding rods 6ft apart and attaching to one another then to the ground bar on the subpanel . My first issue is connecting the 1 in old buried conduit to new 3/4 PVC conduit with a water tight connection . Then how would I set this sub panel up for 120v from 240v . Home Depot item number 100190554 .