I'm running power to my detached garage, I have a 100 amp panel installed and I've completed wiring the circuits in conduit. I will feed the supply from the existing panel in the house via underground UD triplex cable.Approx 90ft.What size aluminum wire do I need and do I need to run a fourth separate ground wire and if so should I remove the bond screw in the new panel and have the ground on a buss by itself? I have an 8ft. ground rod at the new panel, do I need another one?
The wire size should be a # 3 #3 #4 and a #10 Alum if you use copper you can go down a size,make sue that this wire is made to be direct burial.When you hook it up in the new sub-panel the ground and the neutrals need to separated so you do not need the bonding screw. You do not need to install a ground rod unless you want to ground the building if it is a metal one.