30 CFR § 7.301
Purpose and effective date.
This subpart establishes the specific requirements for MSHA approval of
certain explosion-proof electric motor assemblies intended for use in
approved equipment in underground mines. Applications for approval or
extensions of approval submitted after (insert date three years after
effective date of this subpart) shall meet the requirements of this part.
Those motors that incorporate features not specifically addressed in this
subpart will continue to be evaluated under part 18
[57 FR 61193, Dec. 23, 1992]