I'm building a home and want to have 400 amp service. I understand the way this is done is by running (2) 200 amp panels in the house. My service provider asked me for a riser diagram for this service. I'm not sure how to draw this? Can you help?

I bet I know what he wants. Your probably going to come in to the meter and have two outside main breakers rated at 200 amps. These will go to the 2 main lug (200 Amp) panels.

The riser diagram shows the routing of the cables between the subpanels and the main panel and the locations of the panels.

A "riser" is typically connections between floors, but in this case, I believe, it's the backbone of the electrical service.

A riser is a simple block diagram showing all the conduits, with sizes and quantity and size wire in each conduit. It will show the path of each conduit to each cabinet, meter, and panelboard.

If you give me the details I can sketch one out.