On our large ground mount arrays we run our DC feeders above ground tell we get just adjacent to our inverters. At that point we put each feeder in a separate PVC conduit down into the trench. Length of about 5 feet. We are only running a single ground wire with the above ground route which may have 4 or 5 feeders. When we go underground do we need to split the ground wire and run one in each conduit then back together once we are under ground direct bury?