Section 62A. The provisions of sections sixty-one and sixty-two prohibiting the employment of certain minors shall not prohibit the employment of minors fourteen years of age and older to operate, or to assist in the operation of, small power equipment of the kind utilized by home gardeners nor shall it prohibit the operation of a farm tractor operated on a farm; provided, that such minors under the age of sixteen have been certified as having satisfactorily completed a training program in vocational agriculture by the department of education. The provisions of section sixty-two shall not prohibit the employment of minors sixteen years of age or older, consistent with federal law; provided, that such minors are enrolled in a course of study and training in a co-operative vocational training program, including co-operative agricultural programs, under a state or local authority; and provided, further, that such minors are employed under written agreements, that the work of such minors shall be incidental to their training, that such work shall be intermittent and for short periods of time, shall be under the direct and close supervision of a qualified and experienced person and that safety instruction given in any such course shall be correlated by the employer with on-the-job training. The provisions of sections sixty-one and sixty-two prohibiting the employment of certain minors shall not prohibit the employment of minors who are graduates of trade or vocational high schools; provided that such minors are employed in the same occupation as they were trained for in such trade or vocational school.