Wire rope diameter for perimeter guardrails

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

September 14, 1990

MEMORANDUM FOR: Charles Culver

THRU: Roger Clark

FROM: Roy Gurnham

SUBJECT: Perimeter Guarding Utilizing Wire Rope

Thank you for sending me a copy of your September 7 memo to Pat Clark, subject as above--the acceptance of 1/4 and 1/2-inch wire rope for perimeter guardrails.
In the last paragraph of your memo, you noted your willingness to help if Ms. Clark decides that national office direction is warranted to eliminate inconsistencies and to clarify the standard. In this regard, I thought you might want to know that in the November 25, 1986, NPRM on Subpart M--Fall Protection (1926) the agency proposed several requirements for the criteria for guardrail systems. One of these requirements is that the toprail be at least 1/4-inch diameter or thickness. The 1/4-inch requirement addresses hazards of cuts and lacerations that may occur when an employee grabs the rope. The rulemaking record supports the proposed provision of 1/4" toprails provided they are flagged for visibility. Thus, you can anticipate that the final rule will be clear as to the agency's position.
In addition, in the NPRM for steel erection, we raised an issue regarding perimeter protection. Currently, our position is that the safety railing system required in .750 must be a minimum 1/2-inch wire rope because of the impact load the railing may have to withstand if struck by hoisted steel members. In the NPRM, we are specifically asking for comments on whether we should keep this requirement and whether we should require a conventional two-rail guardrail system for steel work. We have also proposed to remove the words "or equal" which appear in the existing standard after the words "1/2 inch." The "or equal" was a reference to the materials used and not to their strength. This appears to have been misunderstood. The final rule on steel will clearly set forth the requirements for wire rope used as a fall prevention measure.
Please let me know if further clarification of the proposed rules is needed.