29 C.F.R. § 790.8
The use by Congress of the plural form "activities" in the statute makes it clear that in order for an activity to be a "principal" activity, it need not be predominant in some way over all other activities engaged in by the employee in performing his job; rather, an employee may, for purposes of the Portal-to-Portal Act be engaged in several "principal" activities during the workday. The "principal" activities referred to in the statute are activities which the employee is "employed to perform"; they do not include noncompensable "walking, riding, or traveling" of the type referred to in section 4 of the Act. Several guides to determine what constitute "principal activities" was suggested in the legislative debates. One of the members of the conference committee stated to the House of Representatives that "the realities of industrial life," rather than arbitrary standards, "are intended to be applied in defining the term 'principal activity or activities'," and that these words should "be interpreted with due regard to generally established compensation practices in the particular industry and trade." The legislative history further indicates that Congress intended the words "principal activities" to be construed liberally in the light of the foregoing principles to include any work of consequence performed for an employer, no matter when the work is performed. A majority member of the committee which introduced this language into the bill explained to the Senate that it was considered "sufficiently broad to embrace within its terms such activities as are indispensable to the performance of productive work."
Such preparatory activities, which the Administrator has always regarded as work and as compensable under the Fair Labor Standards Act, remain so under the Portal Act, regardless of contrary custom or contract.
29 C.F.R. §790.8