Warning line systems and their use must conform to the following provisions:

Warning line system specifications used on roofs with a pitch of four in 12 or less for roofing work, leading edge work and on low pitched open sided surfaces for work activities other than roofing work or leading edge work. The employer must ensure the following:

(1) Warning lines must be erected around all unprotected sides and edges of the work area.

(a) Warning lines used during roofing work:

(i) When roofing work is taking place or when mechanical equipment is not being used, the warning line must be erected not less than six feet (1.8 m) from the edge of the roof;

(ii) When mechanical equipment is being used, the warning line must be erected not less than six feet (1.8 m) from the roof edge which is parallel to the direction of mechanical equipment operation, and not less than 10 feet (3.1 m) from the roof edge which is perpendicular to the direction of mechanical equipment operation.

(b) Warning lines erected for leading edge work. Warning lines must be erected to separate employees who are engaged in leading edge work (between the forward edge of the warning line and the leading edge), from other work areas on the low pitched surface. The employer must ensure:

(i) The warning line is erected not less than six feet nor more than 25 feet from the leading edge; and

(ii) Fall arrest systems as described in WAC 296-880-40020 or fall restraint systems as described in WAC 296-880-40025 must be used to protect employees engaged in constructing the leading edge.

(c) Warning lines erected on low pitched open sided surfaces for work activities other than roofing work, or leading edge work must be erected not less than 15 feet from the unprotected sides or edges of the open sided surface.

(2) The warning line must consist of a rope, wire, or chain and supporting stanchions erected as follows:

(a) The rope, wire, or chain must be flagged at not more than six foot (1.8 m) intervals with high visibility material. Highly visible caution or danger tape as described in (d) of this subsection, does not need to be flagged.

(b) The rope, wire, or chain must be rigged and supported in such a way that its lowest point (including sag) is no less than 36 inches from the surface and its highest point is no more than 45 inches from the surface.

(c) After being erected, with the rope, wire or chain attached, stanchions must be capable of resisting, without tipping over, a force of at least 16 pounds (71 N) applied horizontally against the stanchion, 30 inches (0.76 m) above the surface, perpendicular to the warning line, and in the direction of the unprotected sides or edges of the surface.

(d) The rope, wire, or chain must have a minimum tensile strength of 500 pounds (2.22 kN), and after being attached to the stanchions, must be capable of supporting, without breaking, the loads applied to the stanchions. Highly visible caution or danger tape may be used in lieu of rope, wire, or chain as long as it is at least three inches wide and three mils thick, and has a tensile strength of at least 200 pounds.

(e) The line must be attached at each stanchion in such a way that pulling on one section of the line between stanchions will not result in slack being taken up in adjacent sections before the stanchion tips over.

(3) The employer must erect access paths as follows:

(a) Points of access, materials handling areas, and storage areas must be connected to the work area by a clear access path formed by two warning lines.

(b) When the path to a point of access is not in use, the employer must place a rope, wire, or chain, equal in strength and height to the warning line, across the path at the point where the path intersects the warning line erected around the work area.