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.

November 13, 1991

Mr. D. Joe Comeau
Project Engineer
Bath Iron Works Corp.
700 Washington Street
Bath, Maine 04530

Dear Mr. Comeau:

Thank you for your letter of June 18, concerning the proper wiring of a new overhead crane being purchased by the Bath Iron Works (BIW) from the Harnischfeger (P&H) company. Your letter was forwarded to this office for reply on October 10. Please excuse the delay in response.

The Occupational Safety and Health administration (OSHA) has specific standards concerning the acceptable wiring of overhead gantry cranes used in workplaces. 29 CFR 1910.303(a) specifies that conductors shall be acceptable only if they are approved. Further, 29 CFR 1910.303(b)(1)(i) specifies that the wiring shall be suitable ford the installation. 29 CFR 1910.305(g)(1)(i) requires that flexible cords be approved and suitable for the conditions of use and location. A copy of these standards is enclosed.

Conductor wiring that is "approved" and "acceptable" to OSHA is that which is "accepted" and has been tested by a nationally recognized testing laboratory and determined to conform to specific plans or to procedures of applicable codes (Ref. 29 CFR 1910.399). In this instance, the applicable code is the National Electric Code, NFPA 70-1990, Section 610.

Section 610-11 of the NEC 70-1990 requires that, "conductors shall be enclosed in raceways or be Type MC cable, or Type MI cable". In either event, the cord does not recognize any cord as being applicable for usage on cranes with an exception for the wiring of pendants. Although the general language of the OSHA standard at 29 CFR 1910.305(g)(1)(i)(E) may tend to confuse the issue, the standard at Section 610-11 of the NEC 70-1990 clarifies the fact that only approved and specified flexible cables are permitted to be installed upon cranes. A copy of the pertinent portion of the NEC 70-1990 is enclosed.

The type SO conductor is specified by NEC 70-1990, Table 400-4, to be Hard Service Cord and may be used for wiring a pendant. Otherwise, it is not acceptable wiring for a crane. Only type MC or MI cable are acceptable for wiring a crane. The use of type SO, flexible cord as the wiring media on the new BIW bridge crane would be considered a violation of 29 CFR 1910.303(b)(1)(i) and 29 CFR 1910.305(g)(1)(i).

If we may be of further assistance, please contact us.


Patricia K. Clark, Director
Directorate of Compliance Programs