1. (1) You must install fixed stairs where:

   1. (a) Employees travel between different levels on a predictable and regular basis.
   2. (b) Access to platforms is required to give routine attention to equipment under operation.
   3. (c) Daily movement between elevations is required to gauge, inspect, and maintain equipment where those work assignments may expose employees to acids, caustics, gases, or other harmful substances.
   4. (d) Carrying tools or equipment by hand is a normal work requirement.

2. (2) You must not use spiral stairways except as secondary exit routes.

   Note:	• You can use fixed ladders for climbing elevated structures, such as tanks, towers, and overhead traveling cranes, when their use is common practice in your industry.
   	• You can use winding stairways on tanks and similar round structures if the structure's diameter is at least five feet.
   	• You could use a spiral stairway as an exit route in a restricted area that lacks room for a conventional stairway.

   Definitions:	• A stairway or fixed stairs is a series of steps and landings:
   	– Leading from one level or floor to another.
   	– Leading to platforms, pits, boiler rooms, crossovers, or around machinery, tanks, and other equipment.
   	– Used more or less continuously or routinely by employees or only occasionally by specific individuals.
   	– With three or more risers.
   	• A riser is the vertical part of the step at the back of a tread that rises to the front of the tread above.
   	• A tread is the horizontal part of the step. Tread width is the distance from the front of the tread to the back.

   Stair Components

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[Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, and 49.17.060. WSR 18-22-116, § 296-800-25005, filed 11/6/18, effective 12/7/18. Statutory Authority: RCW 49.17.010, [49.17].040, and [49.17].050. WSR 01-23-060, § 296-800-25005, filed 11/20/01, effective 12/1/01; WSR 01-11-038, § 296-800-25005, filed 5/9/01, effective 9/1/01.]