Warning lines shall consist of ropes, wires, or chains, and supporting stanchions erected as follows:
OSHA: A warning line is used 15' or more from the edge. The TrafFix Devices Roof Edge Delineator warning line meets or exceeds the requirements in 1926.502(f)(2).
The rope, wire, or chain shall be flagged at not more than 6-foot (1.8 m) intervals with high-visibility material;
Manufacturers Recommendation: Spacing between the roof edge delineators to be 6' - 10' (1.8 - 3 m).
The rope, wire, or chain shall be rigged and supported in such a way that its lowest point (including sag) is no less thatn 34 inches (0.9 m) from the walking/working surface and its highest point is no more than 39 inches (1.0 m) from the walking/working surface;
After being erected, with the rope, wire, or change attached, stanchions shall be capable of resisting, without tipping over, a force of at least 16 pounds (71 N) applied horizontally against the stanchion, 30 inches (0.8 m) above the walking/working surface, perpendicular to the warning line, and in the direction of the floor, roof, or platform edge;
The rope, wire, or chain shall have a minimum tensile strength of 500 pounds (2.22 kN), and after being attached to the stanchions, shall be capable of supporting, without breaking, the loads applied to the stanchions as prescribed in paragraph (f)(2)(iii) of this section; and
The line shall 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.
No employee shall be allowed in the area between a roof edge and a warning line unless the employee is performing roofing work in that area.
Mechanical equipment on roofs shall be used or stored only in areas where employees are protected by a warning line system, guardrail system, or personal fall arrest system.

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