View all text of Subpart A [§ 18.1 - § 18.16]
§ 18.14 - Identification of tested noncertified explosion-proof enclosures.
An enclosure that meets all applicable requirements of this part, but has not been certified by MSHA, shall be identified by a permanent marking on it in a conspicuous location. The design of such marking shall consist of capital letters USMSHA not less than 1/4 inch in height, enclosed in a circle not less than 1 inch in diameter.