29 C.F.R. § 785.12 Work performed away from the premises or job site.
Title 29 - Labor
The rule is also applicable to work performed away from the premises or the job site, or even at home. If the employer knows or has reason to believe that the work is being performed, he must count the time as hours worked.
Title 29: Labor
PART 785—HOURS WORKED
Subpart C—Application of Principles
Employees “Suffered or Permitted” to Work
§ 785.12 Work performed away from the premises or job site.