(a) Except as otherwise provided by law, when a personal injury is received by a servant or employee in the service or business of the master or employer, the master or employer is liable to answer in damages to such servant or employee, as if he were a stranger and not engaged in such service or employment, provided such liability is enforced in a court of competent jurisdiction, in the cases following:

(1) When the injury is caused by reason of any defect in the condition of the ways, works, machinery or plant connected with or used in the business of the master or employer.

(2) When the injury is caused by reason of the negligence of any person in the service or employment of the master or employer who has any superintendence intrusted to him, while in the exercise of such superintendence.

(3) When such injury is caused by reason of the negligence of any person in the service or employment of the master or employer, to whose orders or directions the servant or employee at the time of the injury was bound to conform and did conform, if such injuries resulted from his having so conformed.

(4) When such injury is caused by reason of the act or omission of any person in the service or employment of the master or employer, done or made in obedience to the rules and regulations or bylaws of the master or employer, or in obedience to particular instructions given by any person delegated with the authority of the master or employer in that behalf.

(5) When such injury is caused by reason of the negligence of any person in the service or employment of the master or employer, who has charge or control of any signal, points, locomotive, engine, electric motor, switch, car or train, upon a railway or any part of the track of a railway.

(b) The master or employer is not liable under this section, if the servant or employee knew of the defect or negligence causing the injury and failed in a reasonable time to give information thereof to the master or employer, or to some person superior to himself engaged in the service or employment of the master or employer, unless the master or employer, or such superior, already knew of such defect or negligence, nor is the master or employer liable under subdivision (a) (1) unless the defect therein mentioned arose from, or had not been discovered or remedied, owing to the negligence of the master or employer, or of some person in the service of the master or employer, and intrusted by him with the duty of seeing that the ways, works, machinery or plant were in proper condition, but in no event shall it be contributory negligence or an assumption of the risk on the part of a servant to remain in the employment of the master or employer after knowledge of the defect or negligence causing the injury, unless he be a servant whose duty it is to remedy the defect or who committed the negligent act causing the injury complained of.