If an applicant desires to change any feature of approved equipment or a certified component, he shall first obtain MSHA's concurrence pursuant to the following procedure:

(a)(1) Application shall be made as for an original approval or letter of certification requesting that the existing approval or certification be extended to cover the proposed changes and shall be accompanied by drawings, specifications, and related information, showing the changes in detail.

(2) Where the applicant for approval has used an independent laboratory under part 6 of this chapter to perform, in whole or in part, the necessary testing and evaluation for approval of changes to an approved or certified product under this part, the applicant must provide to MSHA as part of the approval application:

(i) Written evidence of the laboratory's independence and current recognition by a laboratory accrediting organization;

(ii) Complete technical explanation of how the product complies with each requirement in the applicable MSHA product approval requirements;

(iii) Identification of components or features of the product that are critical to the safety of the product; and

(iv) All documentation, including drawings and specifications, as submitted to the independent laboratory by the applicant and as required by this part.

(b) The application will be examined by MSHA to determine whether inspection or testing will be required. Testing will be required if there is a possibility that the change(s) may adversely affect safety.

(c) An application for a formal extension of approval or certification must have a list of new or revised drawings, specifications, and information related to the changes to be added to those already on file for the original approval or certification. MSHA will issue a formal extension of approval or certification to a completely assembled electrical machine or accessory, if each component of such electrical machine or accessory:

(1) Meets the requirements in subparts B through E of this part; or

(2) Meets the requirements in approved voluntary consensus standards (see § 18.101).

(d) Revisions in drawings or specifications that do not involve actual change in the explosion-proof features of equipment may be handled informally.