(1) Principal Activities.
(a) The term "principal activities" includes all activities which are an integral part of a principal activity. Two examples of what is meant by an integral part of a principal activity are:
(i) In connection with the operation of a lathe, an employee will frequently at the commencement of his workday, oil, grease, or clean his machine, or install a new cutting tool. Such activities are an integral part of the principal activity, and are included within such term.
(ii) In the case of a garment worker in a textile mill, who is required to report 30 minutes before other employees report to commence their principal activities, and who during such 30 minutes distributes clothing or parts of clothing at the workbenches of other employees and gets machines in readiness for operation by other employees, such activities are among the principal activities of such employee. Such preparatory activities, which the commissioner has always regarded as work and as compensable under the Montana Minimum Wage Law, remain so, regardless of contrary custom or contract.
(b) Among the activities included as an integral part of the principal activity are those closely related activities which are indispensable to its performance. If an employee in a chemical plant, for example, cannot perform his principal activities without putting on certain clothes, changing clothes on the employer's premises at the beginning and end of the workday would be an integral part of the employee's principal activity. On the other hand, if changing clothes is merely a convenience to the employee and not directly related to his principal activities it would be considered as a "preliminary" activity rather than a principal part of the activity. However, activities such as checking in and out and waiting in line to do so would not
ordinarily be regarded as integral parts of the principal activity or activities.
(2) Illustrative U.S. Supreme Court Decisions. These principles have guided the Administrator in the enforcement of the law. Two cases decided by the U.S. Supreme Court further illustrate the types of activities which are considered an integral part of the employee's jobs. In one, employees changed their clothes and took showers in a battery plant where the manufacturing process involved the extensive use of caustic and toxic materials. Steiner v. Mitchell, 350 U.S. 247 (1956) . In another case Knifemen in a meatpacking plant sharpened their knives before and after their scheduled workday. (Mitchell v. King Packing Co., 350 U.S. (1956) . In both cases the Supreme Court held that these activities are an integral and indispensable part of the employee's principal activities.