Does an employer have "actual knowledge" of dangerous equipment used by a contractor?

2 By the term "actual knowledge" we mean notice of facts which would cause a reasonable employer to foresee injury to others if he failed to exercise his retained powers to compel the contractor to use safe equipment. Although the employer is under no affirmative duty to inspect his contractor's equipment (Kuntz v. Del E. Webb Constr. Co., supra, 57 Cal.2d 100, 107, 18 Cal.Rptr. 527, 368 P.2d 127), if he is told by others that the equipment is dangerous he has actual notice of facts which would cause a reasonable employer to investigate further.