30 CFR § 77.405 Performing work from a raised position; safeguards.
(a) Men shall not work on or from a piece of mobile equipment in a
raised position until it has been blocked in place securely. This does not
preclude the use of equipment specifically designed as elevated mobile work
(b) No work shall be performed under machinery or equipment that has
been raised until such machinery or equipment has been securely blocked in
U.S. Department of Labor | Mine Safety and Health Administration (MSHA) | 1100 Wilson Boulevard, 21st Floor | Arlington, VA 22209-3939 www.msha.gov | Telephone: (202) 693-9400 | Fax-on-demand: (202) 693-9401