“Oppressive child labor” means a condition of employment under which (1) any employee under the age of 16 years is employed by an employer (other than a parent or a person standing in place of a parent employing his own child or a child in his custody under the age of 16 years in an occupation other than manufacturing or mining or an occupation found by the Secretary of Labor to be particularly hazardous for the employment of children between the ages of 16 and 18 years or detrimental to their health or well-being) in any occupation, or (2) any employee between the ages of 16 and 18 years is employed by an employer in any occupation which the Secretary of Labor shall find and by order declare to be particularly hazardous for the employment of children between such ages or detrimental to their health or well-being; but oppressive child labor shall not be deemed to exist by virtue of the employment in any occupation of any person with respect to whom the employer shall have on file an unexpired certificate issued and held pursuant to regulations of the Secretary of Labor certifying that such person is above the oppressive child labor age. The Secretary of Labor shall provide by regulation or by order that the employment of employees between the ages of 14 and 16 years in occupations other than manufacturing and mining shall not be deemed to constitute oppressive child labor if and to the extent that the Secretary of Labor determines that such employment is confined to periods which will not interfere with their schooling and to conditions which will not interfere with their health and well-being.