I am adding a meter and separate service to a "Mother in Law" apt. in a detached building. I placed a combo meter/main distribution box on the side of the main house next to the existing meter and ran a pipe up to a weatherhead two feet from the existing drop. Then ran from the new main box underground to a subpanel in the detached building. The POCO is OK with it and waiting to come and connect the pitails together and install an upgraded service drop from the pole. The WA State LnI Inspector vetoed the installation and wants to have a group disconnect on the outside of the main house. He cites 2008 NEC 230.72(A). However I think there is an exception for a detached building when to Service Entrance Connections are fed from the same lateral or drop. What should I cite to inspector? I am an EE and not a code expert. He thinks he is the Lee Baily of electricity!

Sorry, but this is basic Code 101, so the inspector is no genius. POCO does not follow NFPA 70, so they don't care.

The only exception for 230.72 (A) is related to Fire Pumps.

When firemen arrive, they expect all service disconnects to be in one location.

What you may be thinking of, is when under special conditions and permission, such as a large building, and it has multiple service entrances, then it is not practical to group disconnects, and placards shall indicate at each service location the location of the other services.

Plus the detached structure needs a service disconnecting means at that building.

Sounds like he is being picky thou, if it is right around the corner. Inspectors tend to be picky with home owners doing their own work. But it is up to him to interpret the "grouping" of the service disconnecting means.

You may, if you have the fortitude, request an appeal, even take it to the State Inspector for a decision.