Wash. Rev. Code § 49.24.290
In all shafts where men are hoisted or lowered, an iron-bonneted cage shall be used for the conveyance of men, but this provision shall not apply to shafts in the process of sinking or during the dismantling of the shaft after work in the tunnel is substantially completed.
Cages shall be provided with bonnets consisting of two steel plates not less than three-sixteenths of an inch in thickness, sloping toward each side and so arranged that they may be readily pushed upward to afford egress to persons therein, and such bonnet shall cover the top of the cage in such manner as to protect persons in the cage from falling objects.
Cages shall be entirely enclosed on two sides with solid partition or wire mesh not less than No. 8 U.S. Standard gauge, no opening in which shall exceed two inches.
Cages shall be provided with hanging chains or other similar devices for hand holds.
Every cage shall be provided with an approved safety catch of sufficient strength to hold the cage with its maximum load at any point in the shaft.
All parts of the hoisting apparatus, cables, brakes, guides and fastenings shall be of the most substantial design and shall be arranged for convenient inspection. The efficiency of all safety devices shall be established by satisfactory tests before the cages are put into service and at least once every three months thereafter and a record thereof kept.
The test of the safety catch shall consist of releasing the cage suddenly in such manner that the safety catches shall have opportunity to grip the guides.
RCW 49.24.290