Re: Service Conductors
I am guessing that you are talking about 6000 amps at 120/240 volts or 120/208 volts. Can you have the utility serve the building at 480 volts, and place 480 ? 120/240 step down transformers in electric rooms, say on every other or every third floor?
As to the de-rating for underground runs, that is a subject of some debate. I would be willing to go for 15 sets of 500 MCM 75C rated copper conductors, with the parallel conduits laid out in a three vertical by five horizontal pattern, with at least 7.5 inches between any two conduits. I cannot speak for the difficulty that a team of electricians might have in installing this run. Also, I would only go for this design concept because you stated that the 6000 amps is the result of an NEC service calculation. See other discussions on this forum for more information about this debate.