Just installed one the other day! One of our projects is an upper end survey of fine million dollar plus homes and half will have the 400A service. The Hydro company wants us to use an outdoor meter with built in CTs (Microlectric brand), from there we bring the service to the main switch and add a splitter. We normally put a 200A panel near the main service, and add 100A subpanels as needed off the splitter throughout the residence (usually top floor, kitchen, and near the backyard for the pool equip, hot tub, etc.)
