Wash. Rev. Code § 80.01.020
Each commissioner shall, before entering upon the duties of his or her office, take and subscribe the constitutional oath of office, and furnish bond to the state in the sum of twenty thousand dollars conditioned for the faithful discharge of the duties of his or her office and for the proper accounting for all funds that may come into his or her possession by virtue of his or her office. Each commissioner shall be a qualified elector of this state and no person in the employ of or holding any official relation to any corporation or person, which corporation or person is subject in whole or in part to regulation by the commission, and no person owning stocks or bonds of any such corporation or who is in any manner pecuniarily interested therein shall be appointed or hold the office of commissioner or be appointed or employed by the commission: PROVIDED, That if any such person shall become the owner of such stocks or bonds or become pecuniarily interested in such corporation otherwise than voluntarily, he or she shall within a reasonable time divest himself or herself of such ownership or interest, and failing to do so his or her office or employment shall become vacant.
RCW 80.01.020