What size conduit is needed for a 400 amp service with 500 mcm wire?

For a 400 amp service using 500 kcmil wire, you typically need a conduit size that can accommodate the wire's physical dimensions and allow for proper bending and installation. According to the National Electrical Code (NEC), you would generally use a minimum of 3-inch conduit for this application. However, the exact size may vary depending on the number of conductors and type of conduit being used, so it's important to consult NEC tables or local codes for precise requirements.