I did a quick review of some of the requirements in the Revised Code of Washington, and in particular, RCW 19.28.041. It seems to be saying that a license is required to install or maintain either (1) Wires that carry current, or (2) Equipment that is operated by current. I don't think empty conduits falls within the scope of the licensing requirements. I certainly may have missed another rule somewhere else in the RCW or the WAC, but that is all I know at the moment.
Charles E. Beck, P.E., Seattle
Comments based on 2014 NEC unless otherwise noted.