Large Industrial site. Owner buys power at 13.8 Volts. Services coming in close to 900 amps at 13.8. Another Utility feeds the other half of the site 25KV Both services are brought down to 480 volts in all areas. (Also 4160 but N/A ). Question code wise? Can two 480 volt feeders ((each from different utility's)) (480 v with ground ( Feeders) be brought to a Transfer Switch ( Power Must keep on Control panels in case of extended outage)[They are already UPS backed up]. Generator is not practical in this application. (Lot more to it then I can say at this time). Both Sources are Owner Feeders remember. Code References>????? Thank You.
Services are very similar to feeders except there is not really any effective overcurrent protection. They say a lot about "outside the building" and then wrote one of the most ambiguous lines in the NEC when they tell you where the disconnect must be when it gets into the building.
Probably the most important sign is the one at each disconnect that tells the firemen and other professionals that there are 2 services and the location of the second disconnect.
230.2(E) Identification. Where a building or structure is supplied by more than one service, or any combination of branch circuits, feeders, and services, a permanent plaque or directory shall be installed at each service disconnect location denoting all other services, feeders, and branch circuits supplying that building or structure and the area served by each. See 225.37. Handbook commentary Section 230.2(E) states that where any combination of branch circuits, feeders, and services supplies power to a building or structure, a permanent plaque or directory must be installed at each service disconnect location to indicate where the other disconnects that feed the building are lo-cated, as illustrated in Exhibit 230.1. All the other services on or in the building or structure and the area served by each must be noted on the plaques or directories. The plaques or directories should be of sufficient durability to withstand the ambient environment. See the commentary following 225.37 for further information on identification of multiple supply sources to a building or structure.
When it comes to safety related issues, the fire marshal is far more stringent than you get from the bare NEC. He is usually a fireman and they look out for their guys. I do question most of those exceptions where they talk about "only qualified people" and "documented switching procedures" myself.