We all know about 404.2(C) and why this came about. Here is the article for those that don't remember
Then I install a brand New Lightolier Onset 3 way. This is similar to the Lutron Maestro with a master and slave unit. Check out the diagram. How is this compliant(C) Switches Controlling Lighting Loads. Where switches control lighting loads supplied by a grounded general purpose branch circuit, the grounded circuit conductor for the controlled lighting circuit shall be provided at the switch location.