Wash. Rev. Code § 19.28.081
No person, firm or corporation engaging in, conducting or carrying on the business of installing wires or equipment to convey electric current, or installing apparatus to be operated by said current, shall be entitled to commence or maintain any suit or action in any court of this state pertaining to any such work or business, without alleging and proving that such person, firm or corporation held, at the time of commencing and performing such work, an unexpired, unrevoked and unsuspended license issued under the provisions of this chapter; and no city or town requiring by ordinance or regulation a permit for inspection or installation of such electrical work, shall issue such permit to any person, firm or corporation not holding such license.
RCW 19.28.081