29 C.F.R. § 1910.30
(a) Fall hazards.
(3) The employer must train each employee in at least the following topics:
(b) Equipment hazards.
(c) Retraining. The employer must retrain an employee when the employer has reason to believe the employee does not have the understanding and skill required by paragraphs (a) and (b) of this section. Situations requiring retraining include, but are not limited to, the following: