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.

August 9, 1978

Mr. J.P. Isherwood
105 Stephen Road
Aptos, California 95003

Dear Mr. Isherwood:

This is in response to your recent letter addressed to Secretary of Labor Marshall, regarding twist lock receptacles and attachment plugs. Please accept our apology for the delay in response.

In answer to your first question, the OSHA standards do not state anywhere that twist lock receptacles must be employed as the only means to come into compliance. In answer to your second question, "rough use" is not explicitly defined in the standards. However, an attachment plug to endure "rough use" would be, for example, and industrial-type or "Hospital Grade" plug rather that the usual domestic-type plug as described, for instance, in the Best's Safety Directory 1976, pages 664-665 (copy enclosed).

Should you desire further clarification, you may find it convenient to contact the California Department of Industrial Relations, which is enforcing the occupational safety and health standards in California. The address and telephoner number of that office follow:

          Donald Vial, Director
          Department of Industrial Relations
          455 Golden Gate Avenue
          San Francisco, California  94102
          Telephone: 916-445-1935


John K. Barto, Chief
Division of Occupational
Safety Programming