Wash. Rev. Code § 80.01.050
A majority of the commissioners shall constitute a quorum for the transaction of any business, for the performance of any duty, or for the exercise of any power of the commission, and may hold hearings at any time or place within or without the state. A quorum of commissioners need not affirm any matter delegated under RCW 80.01.030. Any investigation, inquiry, or hearing which the commission has power to undertake or to hold may be undertaken or held by or before any commissioner or any administrative law judge as provided in RCW 80.01.060. All investigations, inquiries, and hearings of the commission, and all findings, orders, or decisions, made by a commissioner or administrative law judge, when approved and confirmed by the commission or allowed to become final pursuant to RCW 80.01.060 and filed in its office, shall be the orders or decisions of the commission.
RCW 80.01.050