RCW 49.24.320: Location of lights.

(1) While work is in progress, tunnels, stairways, ladderways and all places on the surface where work is being conducted, shall be properly lighted. In shafts more than one hundred feet deep, the shaft below that point shall be lighted.

(2) All places where hoisting, pumping or other machinery is erected and in the proximity of which persons are working or moving about, shall be so lighted when the machine is in operation that the moving parts of such machine can be clearly distinguished.