OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

September 30, 2010

Letter #20100427-9737

Re:  Whether OSHA will rely on ANSI Z359.1-2007, regarding snaphook compressive strength requirements, in enforcing the general duty clause with respect to personal fall arrest systems in construction, as announced in letter #20070920-8088.

Question:  Will OSHA rely on the increased minimum gate compressive strength requirements in ANSI Z-359.1-2007, §§ & in enforcing the general duty clause with respect to snaphooks, including carabiners, on personal fall arrest systems used in construction?

Answer: No. OSHA is rescinding letter #20070920-8088.

Before discussing the reasons for rescinding this letter, an initial explanation as to why OSHA is referring to ANSI standards is necessary.  The construction fall protection standard provides that snaphooks (which, as defined in the standard, includes carabiners) used in personal fall arrest systems must have a minimum tensile strength of 5,000 pounds and must be proof-tested to a minimum tensile load of 3,600 pounds without cracking, breaking, or taking permanent deformation [29 CFR 1926.502(d)(3) and (4)].

The standard does not address the compressive strength of personal fall arrest system snaphooks, which is an important safety consideration.  Without sufficient compressive strength the gate of the snaphook can open, the personal fall arrest equipment can detach from its anchorage, and the employee wearing the equipment can fall.  Therefore,  in appropriate circumstances the general duty clause of the Occupational Safety and Health Act of 1970, section 5(a)(1), 29 U.S.C. 654(a)(1), applies when such snaphooks have insufficient compressive strength.  The general duty clause provides:  "(a) Each employer - (1) shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees..." Generally, a recognized hazard is one that is (1) known to the industry or to safety experts familiar with the hazard, (2) is known to the individual employer, or (3) is known as a matter of common sense.  Thus, although the standard does address the tensile strength of these snaphooks, section 5(a)(1) imposes a duty on the employer to ensure that the compressive strength of the snaphooks is sufficient.

The sufficiency of the compressive strength of snaphooks on personal fall arrest equipment used in construction is appropriately determined by following ANSI A10.32-2004, Fall Protection Systems - American National Standard for Construction and Demolition Operations.  ANSI A10.32-2004, §4.5.3, which provides:

The snaphook or carabiner shall be capable of withstanding a minimum load of 220 pounds without the gate separating from the nose of the snaphook or carabiner body by more than 0.125 inch when tested in accordance with Section  The gate of the snaphook or carabiner shall be capable of withstanding a minimum side load of 350 pounds when tested in accordance with Section  Failure shall be defined as permanent deformation of the gate more than 0.125 inch, or separation of the gate from the body of the snaphook or carabiner body by more than 0.125 inch.

ANSI Z359.1-2007, which sets forth a 3,600-pound, gate compressive strength test, does not apply to construction.  Therefore, letter #20070920-8088, which relied on that ANSI standard with respect to snaphooks on personal fall arrest systems used in construction, is being rescinded.

If you have any questions about this response, or need further clarification on this subject, please contact us by fax at (202) 693-1689. You may also contact us by mail at the U.S. Department of Labor, Directorate of Construction, Office of Construction Standards and Guidance, Room N-3468, 200 Constitution Avenue, N.W., Washington, D.C. 20210.

Thank you for your interest in occupational safety and health.


Ben Bare, Acting Director
Directorate of Construction