Complex voltage drop question?

[e57]

I am bidding on a res. site ltg. project with some really long runs to parts of the yard for fixtures and gfi's. I plan on exiting the house with 2 conduits w/ 1-20amp and 2-20a swd. ckts. underground to a j-box 150+/-' away. Then splice the outlet ckt. and 2 swd. ckts. each to 3 other longer runs 250', 260', 380' away. For the outlet ckt. should I size my wire on the longest run, 530+', @ 20 amps or is there something else here I should consider?

Hey why not jump up to 480 at the house - (NOT INSIDE) then back down at a single 240-120 transformer sized for the total load feeding a small panel as far out as possible and relays for switching out there with it. Granted you'll need to plant a rod for the secondary - but IMO what you save in copper will easily cover that, and the equipment will use up the rest..... Funny how that works...

Anyway once you get the numbers crunched let us in on what gets decided.

And - I'm sure other might chime back in on this - will the OCP work at that length?