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.

January 9, 1989

Jerome Frank, P.E.
Marketing Specialist
International Transformer Corporation
6900 E. Washington Blvd.
Montebello, California 90640

Dear Mr. Frank:

This is response to your letters of August 22 and December 1, 1988, concerning dry type 5-15 kv transformers and provides an interpretation of the terms "acceptable" and "special equipment".

Under the requirement at 29 CFR 1910.303(a), only "approved" equipment is "acceptable" when required or permitted for use in workplaces. 29 CFR 1910.399(a)(1)(i), copy enclosed, defines "acceptable" as those items certified or listed by a nationally recognized testing laboratory (NRTL). Since dry type 5-15 kv transformers are presently tested by NRTL, such as Underwriters' Laboratory (UL), the transformers so certified would be acceptable under the standard.

"Special equipment" is not now, nor has it previously been, defined by the standards. 29 CFR 1910.361 through 1910.380 is reserved for future use of a section to be titled: Safety Requirement for Special Equipment. This term does not apply to dry type transformers.

29 CFR 1907 and 1910, Safety Testing or Certification of Certain Workplace Equipment and Materials, was published as a final rule on April 12, 1988, and addressed the methods by which NRTL's are designated by OSHA. During the next five years, UL and Factory Mutual Research Corporation (FMRC) will continue to be recognized testing laboratories. Additional laboratories are being considered as NRTL's and will be recognized by OSHA for specific types of testing. This modification to the standards has no effect upon the interpretation concerning the transformers.

If we may be of further assistance, please contact [the Office of General Industry Enforcement at 202 693-1850].


Thomas J. Shepich, Director
[Directorate of Enforcement Programs]

[Corrected 2/16/2005]

August 22, 1988

Thomas J. Shepich, Director
Directorate of Compliance Programs
Occupational Safety and Health Administration
U.S. Department of Labor
200 Constitution Avenue, N.W.
Washington, D.C. 20210

Dear Mr. Shepich

It has come to our attention that an interpretation of an OSHA Standard came out of the Technical Support Group of the OSHA Regional Office in Chicago.

Since this is an interpretation from one Region, we are asking for an interpretation as far as the National Office is concerned.

It was stated that:

"a) 1910.361 through 1910.380, Special Equipment, has not been determined yet. The dry type of transformer, 5-15 kv, must be tested and approved by the U.L. (Underwriter Laboratory); they are not considered Special Equipment is "a component or any assembly designed and fabricated for a specific installation, and will never be used in any other operation of installation.

b) 1910.399 (a) paragraph states: "An installation of equipment is acceptable to the Assistant Secretary of Labor if it is tested and approved by a nationally recognized testing laboratory." We would like to inform you that 5-15 kv dry transformers are not considered as Special Equipment. When they are tested and approved by UL, they will be considered as meeting OSHA requirements.

It must be clearly understood that OSHA is not an approving agency, and the term "OSHA approved" must not and should not be used.

If we can be of further service to you, please let us know."

The above covered dry type transformer equipment has not previously been tested by a third party, but now is being tested by UL and similar organizations.

We are asking for clarification as follows:

(1) With reference to 1910.399(a)(1), the definition for "Acceptable", what will OSHA require for new dry type transformers to be "acceptable" when installed in the workplace?

(2) How does the recently issued Standard 29 CFR Part 1910.7, (final rule for Safety testing or certification of certain workplace equipment and materials) dated April 12, 1988, affect this interpretation?

(3) Is the Chicago Regional Office definition of "Special Equipment" correct regarding future OSHA electrical standards? Specifically our concern involves to the following point: Certain electrical equipment such as dry type transformers which until recently no nationally recognized laboratory has every listed, labeled, or certified, has now been accepted for testing by a nationally recognized laboratory.

With third party certification for dry type transformers (5-15 kv) available, we would appreciate an interpretation of the OSHA Standard by the National Office.

Sincerely yours,

Jerome Frank
Marketing Specialist