A commercial establishment supplied by a 208Y/120V, three-phase, four-wire service has a total estimate demand load of 250,000 VA. The total estimated single-phase loading is 35,000 VA. Determine the service overcurrent protection device rating and undergrounded and grounded service conductor size. Use XHHW copper conductor and 75oC device terminal ratings and allow for 25% load growth. Do not use larger than 600 kcmil conductor size.