(a) Except as hereinafter provided, no female eighteen (18) years of age or older shall be employed or permitted to work in, or in connection with, any establishment for more than six (6) days in any one week or more than forty-eight (48) hours in any one week, or more than ten (10) hours in any one day.

Where the strict application of the schedule of hours, provided for by this section, imposes an unnecessary hardship and violates the intent and purpose of this act, the Secretary of Labor and Industry, with the approval of the Industrial Board, may make, alter, amend, and repeal general rules and regulations prescribing variations from said schedule of hours: Provided, That if it should be held hereafter by the courts of this Commonwealth that the power herein sought to be granted to the Secretary of Labor and Industry is, for any reason, invalid, such holding shall not be taken in any case to affect or impair the remaining provisions of this section.

(b) Nothing in this section or in any other provisions of this act shall apply to the employment of females in agricultural field occupations, or in domestic service in the home of the employer, nor shall any provisions of this act which relates to the regulation of hours of employment apply to the work of registered nurses in hospitals, or to the work of females over eighteen years of age who are employed in a bona fide executive, administrative or professional capacity, as confidential secretaries, or as outside salesmen as such terms are defined and delimited from time to time by regulations issued by the Secretary of Labor and Industry with the approval of the Industrial Board.

(c) It shall be unlawful for any female to be employed, or permitted to work, in any occupation dangerous to life or limb, or injurious to the health or morals, as such occupation shall, from time to time, be determined and declared by the Industrial Board. Before any occupation is prohibited the board must give notice of its intention and hold a public hearing.