Hello

I will be installing a new electrical service. It will be a 5 ganged meter socket running 4 apartment panels and 1 landlord panel. Each apartment will have a draw of between 60-67amps and will be on 100Amp panels. The landlord panel will draw between 56-62 amps and will also be on a 100 amp panel. If you calculate the standard draw you get a total of 298 amps and a maximum of 322 amps.
My plan is to come into the 5 ganged meter with one mast up the power company and then directly to the right of the meter mount a trough and run to each panel from the back of the trough right into the building. I hope the trough can come right off the meter socket but I may have to run a piece of conduit.
I have a couple questions about the wires for the service.
1. I would want to use copper 500MCM UV rated wire for the mast. Also, can I derate the neutral or would it need to be the same size. If I can derate it what, would it be?
2. I would use number 1 alum UV rated for the feeder wires to the panels since I am only going to stub into the building and an not runnning conduit all the way to the panels. Is that correct or can I use non UV rated wire
3. What size ground would I need to use for the panels