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• Standard Number: 1926.502(d)(16)(iii); 1926.502(d)(16)(iv); 1926.502(d)(16)(v)


February 9, 1995

Mr. J. Thomas Wolner
D.B. Industries, Inc.
P.O. Box 46
Red Wing, MN 55066-0046


Dear Mr. Wolner:

Your December 5 letter addressed to Ms. Barbara Bielaski requesting an interpretation of the Occupational Safety and Health Administration's (OSHA) final rule on fall protection concerning the criteria for personal fall arrest systems has been forwarded to the Office of Construction and Maritime Compliance Assistance for response.

Your interpretation regarding total fall distance experienced by the user during fall arrest on a horizontal lifeline is correct as stated in your letter. Specifically, the free fall distance is limited to 6 feet; the deceleration distance must not exceed 42 inches; lifeline elongation is not included in deceleration distance; and the total fall distance is unregulated except that the employee cannot make contact with a lower level.

Regarding your question on applying the safety factor, the safety factor of two should be applied based on the anticipated maximum arrest force and not the fall energy. The example in your letter of determining the maximum arresting force and then doubling that figure to arrive at the system design load is the approach to be taken.

If we can be of any further assistance, please contact me or Mr. Dale Cavanaugh of my staff at (202) 219-8136.

Sincerely,



Roy F. Gurnham, P.E., J.D. Director
Office of Construction and Maritime Compliance Assistance



December 5, 1994

Ms. Barbara Bielaski
U.S. Department of Labor, OSHA
200 Constitution Avenue
N.W. Washington D.C. 20210

Subject: Requirements for HLL systems

Dear Barbara,

DB Industries is currently involved in the design, marketing and, sale of a number of horizontal lifeline (HLL) systems for use as part of personal fall arrest systems. During the course of this work, two questions continue to crop up that we would like OSHA's opinion on.

The first question relates to total fall distance. Our understanding of OSHA's position with regards to the total fall distance experienced by the user during fall arrest on an HLL, is that there is no defined limit. To comply with OSHA requirements in Subpart M for example, the free fall must be kept to six feet or less and the deceleration distance must not exceed 42 inches. The final component of the total fall distance for an HLL system is elongation of the lifeline (which is excluded from the deceleration distance by definition) as the arrest occurs. It is our understanding that the elongation portion of the total fall distance is unregulated. Is this a correct assumption provided a worker cannot reach a lower level during fall arrest?

The other area we have questions on concerns the safety factor to be applied to the HLL system. It is unclear to us whether the safety factor of two (2) should be applied based on the anticipated arresting force or, on the fall energy. For example, if one assumed a MAF of 1800 lbs and than doubled this figure to arrive at the system design loads, one set of results could be had. If however, one were to input twice the potential energy into the system than was expected at fall arrest during normal use, another answer could be obtained. Our experience has shown that both methods have been used with very different end results. Can you provide any guidance on this issue?

Sincerely,



J. Thomas Wolner, P.E.



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